Photography BLOG

In the beginning there was platinum and the world was void and without form.  And then God said, “Let there be pyro”, and it was good.’  So maybe I am getting a little carried away.  Using pyro is not exactly a religious experience although some promote it with almost religious fervor. I have Colin & Elizabethbeen accused of being in the latter category.  In reality, I believe excellent platinum/palladium prints can be made from negatives developed in any of the traditional developers given that proper care is taken in controlling the development process. But for me and many other photographers, pyro offers an array of advantages over traditional developers. I wrote of some of these in my article in the September/October 1997 issue of View Camera, “The Advantages of Pyro for Platinum Printing”.

In the winter of 1998, I called Dick Arentz to inquire about the platinum workshop he was holding in the spring. Even though I have been printing and exhibiting platinum/palladium prints for over 8 years, I am always interested in improving my art form. Dick had seen my article, and was interested in talking more about my experience with pyro.  A number of students attending his workshops brought negatives developed in pyro.  His system of printing relies on use of a black and white densitometer to read the negatives.  The effects of pyro stain renders such density readings useless so he was curious if a conversion factor could be established that would correct the density readings for the stain.

I decided to attend his workshop, had a wonderful time, got temporarily lost in the desert for an hour on a field trip, and came away with a suggestion from Dick to do a sensitometric analysis of the effects of pyro stain in platinum printing. To my knowledge, such an analysis had never been done. All of the articles to date including my previous article have been based on intuition, personal experience, and guess work, so I wanted to attempt to find some factual basis for the wide range of folklore and myth on this topic.  I decided to further explore the characteristics of pyro and the stain it produces in a more quantitative approach. I had the good fortune to have just inherited a rather high quality color densitometer so I had the necessary tools.

San XavierNow you must understand that I have resisted the temptation for many years to run detailed film/development tests complete with graphs, charts, and spreadsheets full of data.  My educational background is in the sciences with degrees in both physics and computer science.  My photography is my art, which I pursue to add balance in my life.  I base my photographic explorations on instinct and emotions and I make a great effort to not turn my artistic endeavors into an analytical science project. So to take Dick up on his suggestion was quite a stretch for me.  But in the end, I must say I gained quite a bit of insight about my process, the effects and subtleties of pyro, and why intuitively, I have always felt it to be a superior negative developer for use in printing in platinum/palladium.

There were several areas in particular I wanted to investigate:

1. Show that stain is proportional to silver density
2. Measure the amount of printing density added by the stain
3. Determine if the stain has an even more pronounced effect in the platinum process than in silver printing
4. Determine if pyro contributes to being able to produce both a platinum and silver print from the same negative

My approach was fairly simple. I contact printed a 4×5 Stouffer step tablet onto several sheets of 4×5 TMAX 400 film with identical exposures and developed the film in my standard pyro formula and in D-76.  The goal was to produce a reversed image of the step tablet and then measure the densities on both a black & white densitometer and a color densitometer through the red (R), green (G), and blue (B) filters.  Since platinum is only sensitive to ultraviolet light (extreme blue) the effects of the stain should be seen in the different color density readings i.e. greater density from the blue filter than from the red or green.

The Stouffer step tablet is an ideal tool for this experiment.  It contains 21 steps each one half stop apart or 0.15 difference in density. One stop or zone of density equals 0.3, one and a half stops equals 0.45 of density, two stops equals 0.6, and so on. I used my enlarger fitted with an Aristo cold light as a light source for exposing the step tablet onto the TMAX film.  The films were placed emulsion to emulsion in a contact frame. All exposures were 1 second at f16.  I placed a piece of black gaffer’s tape in the margin of the step tablet to establish a film base + fog (fb+f) reading.  My enlarger is fitted with a Zone VI stabilizer and photocell and I use a digital timer accurate to 0.05 seconds.  This combination produces extremely consistent exposures. The negatives were developed in trays. For the D-76 negative, I used stock solution for 13 minutes at 68 degrees. The pyro negative was developed in a 1:1:15 solution for 15.5 minutes at 68 degrees. (See my previous article for developer formula.)

Each step of each negative and the Stouffer step tablet were read with an X-Rite model 820TR color densitometer yielding density readings for the red, green and blue filters. The negatives and step tablet were also read in a black and white densitometer which was calibrated with the same calibration reference standard traceable to the National Bureau of Standards.  The density data was entered into an Excel spreadsheet and plotted using Excel’s graphing tools.  The density readings of the negatives and step tablet are shown in the graphs in Figures 1-3. The graphs show that for both the step tablet and the D-76 negative, the densities for red, green, and blue filters and the readings from the black and white densitometer are almost identical.

The graph of the pyro negative tells a completely different story. There is a definite divergence of the data for the red, green, and blue filters showing clearly the additive effect of the stain on total negative density.  Note that the black and white readings track almost identically to the red filter readings explaining why black and white densitometers are useless for reading pyro negatives. Both silver and platinum materials are not sensitive to red light so this data can be ignored. The greatest divergence occurs in the line showing blue density. By comparing the blue filter and B&W data, you can see that the stain is adding only a very small amount of density in the shadow values - about a quarter stop(.07). But at the far right end of the scale in the highlight region, the pyro stain is adding a full stop of density (0.34) over the B&W reading showing conclusively that the density added by the stain is indeed proportional to the silver density.

But, blue filter readings of the pyro negative do not give a true indication of how much printing density is added by the stain in a platinum/palladium print.  The blue filter is measuring blue light in the visible spectrum, not the ultraviolet light to which platinum materials are sensitive. Using an Aristo Platinum Printer as a light source, I printed both negatives in platinum/palladium with my standard mixture (60% platinum/40% palladium) and paper, Cranes Parchmont Wove. I included a Stouffer step tablet strip in each print as a reference to normalize the print densities of the negatives.  The print time was adjusted such that step 5 of the reference strip yielded approximately a 90% black (zone 1) in both prints. I read the reflective print density of each step and correlated the negative density in the D-76 and pyro negatives to determine which steps resulted in the same print density. This told me how much printing density the stain added.  The reflective density readings are included in the table in Figure 4.

These prints yield some interesting insights in a number of areas. As expected, the pyro stain has an even greater effect than the blue filter reading indicates.  At the shadow end of the scale, step 17 prints almost exactly the same in both negatives. The blue density of the D-76 negative at this step is .44 with fb+f subtracted, but the blue density of the pyro negative for step 17 is only .29 with fb+f subtracted - a difference of one half stop in blue filter density. Yet the print density is about the same.  Hence the pyro stain is adding one half stop of printing density more in the shadow values than the blue filter readings indicate.

However, the effect of the pyro stain becomes more pronounced at the highlight end of the scale. Step 5 of the D-76 print has approximately the same reflected density as step 2 of the pyro print. The blue density of step 5 on the D-76 negative is 2.06 with fb+f subtracted yet the blue density of step 2 in the pyro negative is 1.54, almost 2 stops less in the blue filter density.  But since these two steps yield approximately the same print density, we can conclude that the pyro stain is adding two stops more printing density than the blue filter reading indicates!

From this data, it appears that it should be possible to obtain a silver print of about the same density range as a platinum print from the same negative. We already know that the stain is adding two full stops of printing density in a platinum print at the highlight end of the scale over what visible blue light would see yet the added printing density at the shadow end of the scale is less than one half stop. Silver papers are sensitive to visible blue and green light. In variable contrast silver papers, blue light results in higher contrast, and green light in lower contrast.  A good example of this is the Aristo VCL4500 variable contrast cold light head. It has two tubes - one blue and one green.  By varying the amount of light from each tube, the contrast of the resulting print is controlled.  The more blue light, the higher the contrast. The more green light, the lower the contrast. The yellowish-brown pyro stain tends to block blue light as shown by the higher density readings for the blue filter.  It passes more green light as shown by the lower density readings for the green filter. Hence a silver print from the same negative will be of lower contrast for a silver based variable contrast paper since the negative is passing more green than blue light.

Polymer Science BuildingTo test this theory, I contact printed the same two negatives on a grade 2 silver paper. The reflective densities of the silver prints are also shown in the table in Figure 4.  The data shows conclusively that the pyro negative yields a print in both platinum/palladium and silver which can represent a subject with a brightness range of 9 stops. The actual print reflective density range of the platinum/palladium print is only about 5 stops but the subject brightness range represented is 9 stops - from step 1 to step 19.  The actual print reflective density range of the silver print is about 6 stops and the subject brightness range represented is also 9 stops - from step 3 to step 21.  Hence, both a platinum and silver print representing the same subject brightness range can easily be made from the same negative.

The same is not true for the D-76 negative.  The subject brightness range of the D-76 negative represented in the platinum/palladium print is 8 stops - from step 3 to step 19.  But the subject brightness range represented in the silver print is only 5.5 stops - from step 9 to step 20. Thus, the subject brightness range rendered in the platinum/palladium print and the silver print from the D-76 negative differs by 2.5 stops! This difference might be narrowed through use of much lower contrast grades of silver paper but the separation of values will be reduced.  Split filter printing might compensate for this but now you are getting into more complex print manipulation. Another alternative is to reduce development of the D-76 negative to print better on silver paper, but then more potassium chlorate must be added to the platinum/palladium sensitizer resulting in more uneven tones in the print.  Either way, print quality compromises are required if one wants to print both platinum and silver from the same negative developed in D-76 or other traditional non-staining developer formulas.

This series of tests provided a few more insights into advantages of using pyro for platinum printing. Because of the additive density effects of the stain, much less potassium chlorate is required for the same print contrast in the platinum print than for a negative developed in traditional developers. Increased amounts of chlorate tend to cause grainy or coarse tones in platinum prints. Using less chlorate results in smoother tones and allows for better separation of highlights because the silver densities are not being pushed to the film’s maximum limits. Some printers might consider this a disadvantage because since you are working in the mid-range of contrast grades with very little chlorate, you do not have as much latitude to reduce print contrast from a high contrast negative.  But in my personal experience, I have rarely had a need to lower contrast in a platinum/palladium print. I usually need to increase contrast.

Another observation from these tests is that my time and temperature combination for pyro development yielded a longer scale negative than D-76. As we saw in the print comparisons, pyro compresses the subject brightness range resulting in a print with 9 stops of subject brightness without overly compressing any one portion of the scale. Prior to running these tests, my experiences in photographing in cathedrals and the canyons of southern Utah showed this characteristic of pyro. I frequently exposed images with a brightness range from zone 2 to zone 11 and this range was accurately rendered in the resulting prints. I believe that adjustments to the development of a D-76 negative may be able to produce similar results although separation in the shadow values might be reduced. This area requires further investigation before any conclusions can be made.

Delicate TreesAs we discussed this project, Dick originally thought that my tests could yield a conversion factor which could be applied to a pyro negative to compensate for the effects of the stain in printing. However, the amount of stain produced by pyro is unique to each photographer’s process depending on method of development, formula, dilution, development time, and degree of developer oxidation.   Therefore, the data presented here can only be used as a general reference on the effects of pyro stain in platinum printing.  Each photographer must run his or her own tests for their own development process. From an artistic perspective, this is one reason why I like pyro so much. Because the effects of pyro and its stain vary from user to user, it results in a more personal interpretation or unique signature of the photographer using it.

This little research project as been a pleasant diversion and I hope it provides some insight into the effects and advantages of pyro in platinum printing. But it can not replace the pleasure of seeing images come alive in a good printing session. It is time to set aside the densitometer and resume my artistic endeavors.  Here’s wishing you good printing no matter what film developer you use.

My pyro formula is a variation on the original Wimberly WD2D formula originally published in Petersen’s Photographic in 1978 and later re-published in Darkroom and Creative Camera Techniques.  My formula and processing practices do not necessarily follow the philosophy of maximum stain/minimum silver. Stain is your friend but it can be your enemy in printing alternative processes.  Too much stain can easily extend printing times to an hour which I find unacceptable.  The pyro-metol formula is identical to Wimberly’s WD2D formula except for the restraining agent in solution B.  The formula is as follows:

Bryce PointOriginally, I included 1.1 grams of potassium bromide in Solution B as a substitution for Kodak anti-fog which was called for in the original WD2D formula. I had difficulty obtaining sufficient contrast in the resulting negatives and development times were exceedingly long. On the advice of Gordon Hutchings, I eliminated the bromide which solved both problems.  I have not noticed any fogging problems after a couple thousand 4×5 and 8×10 negatives.

I use TMAX 400 in 4×5 and 8×10 exclusively for my platinum negatives. Its pronounced contrast and beautiful edge effects are a perfect combination for platinum.  I have tried Tri-X and found results similar to TMAX but the reciprocity characteristics requiring ever increasing exposure in low light situations make long exposures difficult to manage.  Many of the exposures inside the cathedrals required 10-30 minutes on TMAX 400 which would have been at least an hour or two with Tri-X.  Also, edge effects do not seem nearly as pronounced with Tri-X as with TMAX.  I rate TMAX 400 at 200 and reduce development to maintain good fat shadow detail yet printable highlights.

Negatives are developed in trays - eight to twelve 4×5 sheets or six to eight 8×10 sheets at a time. Agitation is constant in that I am constantly moving the bottom sheet to the top of the pile throughout the development process. The negatives are presoaked in water for 2 minutes and then transferred to the pyro. My standard developer dilution is 1:1:15 for solutions A, B, and water respectively. This dilution seems to work well for normal and both minus and plus development of negatives. For normal negatives, I develop TMAX 400 at 68 degrees for 15.5 minutes plus 30 seconds to displace the water from the presoak. I have not tried other dilutions since this one has served all of my needs. The negatives are developed emulsion side up and half way through the development time, I rotate the stack 180 degrees to even out development.  Otherwise the end of the negatives that are lifted to remove the bottom negative from the stack tend to get slightly less development since they are repeatedly lifted above the surface of the solution even if only for a brief moment.  I have tried emulsion side down development but had too many scratches in the negatives which I can not completely explain.

A tray of distilled water is used instead of an acid fixing bath.  I figure any developing action which continues before the negatives hit the fixer only enhances the shadow detail with very little effect on the highlights.  I started this practice when I was having some problems with my development process and was trying to eliminate variables. I saw no significant differences between an acid stop and a water stop bath so I stayed with the water. It is cheaper particularly since the stop bath must be discarded after each process cycle because of the oxidized pyro carry over from the developer tray.

Contrary to  most of the experts’ recommendations I use a pre-packaged hardening fixer, Kodak Fixer(gasp!), which undoubtedly removes some of the stain. Some day I may move to mixing my own fixer for economy but prefer to pay a little more and spend my time on the creative process rather than mixing chemicals.  Fix TMAX 400 for 10 minutes in Kodak Fixer. Some of the pink anti-halation dye will remain after the fixing bath but this will disappear after hypo clearing agent and washing.  Use fresh fixer for each batch of film or a two bath method with the second bath used as the first bath for the next batch of film.

Evening on the ColoradoThe developing action of pyro and the associated stain effects are very sensitive to small variations in developer temperature. Pyro oxidizes more rapidly as the temperature of the solution increases.  If you tray develop, use a water bath around the trays. Without a water bath, a 68 degree solution will easily climb to 70 degrees during development just from heat transfer from your fingers.  If the air temperature in the room is higher than the developing temperature, the solution temperatures will gradually rise as well without a water bath.  A two degree increase in developing temperature can have a significant effect on total negative density for a pyro negative. The accelerated action of pyro on both silver density and increased stain is additive in the resulting negative and therefore has an almost doubling effect as if the negative had actually been developed even longer.  The increase in stain has the greatest impact for platinum printing. Pyro does not oxidize as quickly in a full closed tank.  The staining effects are less pronounced for the same development time which must be taken into account when developing roll film intended for platinum printing in pyro.

Tri-Color Gum with Cyanotype
by Sam Wang

Gum or gum-bichromate printing is a very flexible process capable of producing very beautiful and permanent prints. Although volume upon volumes have already been written on the process, few contain information that readers can follow to obtain repeatable results. This is partly because we generally do not work in scientifically monitored environments and often have no real control on the great number of variables. Each of us then needs to develop techniques based on what works for him or for her. This article is a quick run-through on what has worked for me.

My tri-color gum process may be different from others’ in three areas:

1/ Digitally created color-separation negatives,
2/ homemade gum, and
3/ the use of cyanotype for one of the colors.

These contribute to the success of my prints, as well as to their distinctive “look.” This look may not be suitable for anyone else. What follows are some details that more seasoned alt-process printers may find useful, but are by no means a fail-proof step by step guide.

Please be aware that all chemicals need to be handled with care. Ammonium dichromate is a very toxic substance and a known carcinogen.  Do not ingest, breath, or have skin contact with it, and do not allow the dichromate in dry form to come near flames, as it is also combustible.

First, a couple words on my imagery: from way back I’ve been interested in intermixing scenes from different times and places to suggest something beyond the surfaces and the obvious. I leave the simple straightforward and confrontational approaches to the traditional silver prints that I continue to make. With digital images, I can freely manipulate and use subjective colors, colors that don’t have to be perfect or correct. A great variety of methods are on hand to connect and interlace images in the digital arena, much superior to physically cutting and taping pieces of Kodalith films together as I once did for photo-silkscreen. Other than that, I do not hold any central theme or philosophy with my imagery, except that there be a hint of ties to photographic reality and that each is a new vehicle for discovery.

DIGITAL COLOR SEPARATION NEGATIVES

When I’m satisfied with an image on the computer screen, I take the following Photoshop steps to color-separate it into 3 separate full size greyscale negatives:

1. Invert (Image -> Adjustments -> Invert) and then flip the image horizontally (Image -> Rotate Canvas -> Flip Canvas Horizontal).
2. Increase Canvas size on one side to allow room to put in the letters “CYM” (Image -> Canvas Size).

3. Split Channels - separating the RGB file into 3 distinct grayscale documents.
4. On each of these documents, erase 2 of the letters, leaving one to show the printer color, i.e. on the Red generated file, erase “Y” and “M”, leaving “C” for cyan (cyan is the complementary color to red); on the Green generated file, erase “C” and “Y”, leaving “M”; and on the Blue generated file, erase “C” and “M”, leaving “Y”.
5. Adjust and apply the proper curve for the particular printing process, i.e. gum (cyanotype in this case can use the same curve). This curve was developed by trial and error. (To get a “ballpark” curve, try printing a black to white gradient on transparency material and test print it in cyanotype. Keep adjusting and saving and refining the curve untill the tonal range in the cyanotype matches that of the screen. It’s a tedious process. Mark Nelson’s promised software should make this much easier and more accurate.)

6. Print on the proper transparency material. Using black ink only, I usually print on the readily available (and cheaper) overhead transparency material for inkjet instead of the premium quality variety from Pictorico. Printing on Pictorico OHP with color inks obviously would also work and may alleviate some problems such as banding that sometimes occur.

The density range I usually aim for is about log 1.0. However, one of my “more successful” prints, one of a dead bird, was made from negatives printed in color inks on an HP printer with a much higher density range. So when I say, “I don’t know” in answer to the question, “What’s the negative density range for gum or cyanotype?” I’m not putting anyone on. It appears that anytime I felt I found some sure way to do one thing, something else would happen to remind me that I don’t know it all.

I encountered many difficulties when I first began making gum prints: it was not clear which paper to use; my exposing light (a sun lamp) was highly inadequate; plus a myriad of other problems. I was also using panchromatic film, making “in-camera” separations, holding RGB filters in front of the camera lens for three exposures onto 3 separate pieces of black and white film. I also made color separation negatives from color transparencies by enlarging in the darkroom. Both of these methods were not only tedious but often produced negatives very difficult to print - densities and contrasts that were hard to control and working in the dark with panchromatic film was definitely not fun. The fact that I got a few halfway decent prints is something of a small miracle, and represents hundreds of hours of frustrating work! Digital negatives by comparison greatly simplify the process. Nowadays I use color images from digital cameras as well as scans from slides, and the negatives print much more predictably.

CYANOTYPE

When I first began using cyanotype as a color with gum, it was because tri-color gum and tri-color casein were causing many problems: one was staining, and another was the graininess/ mottling that appeared after a few coats of gum. Working with the cyanotype/gum combination not only eliminated these problems, but it also made registration much easier, and resulted in images with more clarity and apparent sharpness – qualities nice to have when I wanted them.

Many well-sized papers work well with gum printing. For many years I used Rives Heavyweight, a nice paper but also very soft – it abrades easily and with more than a couple layers of gum you begin to get a grainy effect. Some folks may find this grainy look desirable but not me. Watercolor papers seem to do better. Paper choice also affects the cyan layer a lot, as each paper will give a different blue, bluish green, or royal blue after a layer of gum is laid on it. The paper is not additionally sized (watercolor papers are already well-sized) but soaked in hot water for about an hour to pre-shrink, and allowed to dry thoroughly before use. Watercolor papers I have found to work well include Fabriano UNO and Fabriano 50.

I use the traditional cyanotype formula (“classic” solution A: 50 g ferric ammonium citrate to 250 cc water; solution B: 25 g potassium ferricyanide to 250 cc water). To print the cyan layer with the “C” negative, the one from the Red channel, I use 2 parts A with 1 part B of the stock solutions for increased printing speed. I also add a little vinegar to the first wash, or soak, to further increase speed and to smooth out the highlight tonality. A word of caution: the addition of vinegar to the wash water will also cause some of the blue to float and it will reattach to the tray and everything else. To minimize the problem, use a fresh bath of vinegar with water for each print. In addition, the print needs to be immersed in it in one smooth motion or edge lines could form. The cyan layer is “developed” for only as long as it is necessary to be free of the yellow unexposed emulsion. In most cases this takes no more than a couple of minutes.

GUM

I prefer to mix my own gum by dissolving gum-arabic powder or granules in water, at 1 part gum to 2 parts water. After it’s all dissolved I add a few drops of 100% thymol (10 grams thymol in 10 cc of isopropyl alcohol) to preserve the solution. I find this gum to “develop” cleanly and in less time than the graphic arts product often called Gum-14, which can vary a lot from batch to batch and often contains too much preservative to develop (re-dissolve) quickly.

YELLOW LAYER

Prepare a gum solution and add yellow pigment. The homemade gum is diluted 1:1 with water. Then yellow pigment, usually Hansa Yellow, is added, mixed well, and test-brushed till the color depth is about right. Once it looks about right I add the sensitizer, ammonium dichromate. I use a homemade scoop to measure, and stir it in with a soft brush till completely dissolved. The scoop is made from a narrow piece of 1/4” thick acrylic: drill a 1/4” hole and block one end of it and you have a scoop to measure out enough dichromate (about 0.3 g) for 10 cc of gum-pigment mixture. This is close to the minimum amount necessary to sensitize gum without much speed loss. It is also slightly higher contrast and fits negatives with density range of approximately log 1.0, roughly similar to that of a normal enlarging negative. Adding more dichromate will increase speed a little and will print a log 1.25 negative, but that also means dumping more of the toxic chemicals down the sewer line. This method allows me to visually evaluate the amount of pigment I need, without being influenced by the strong yellow of the dichromate. It also helps keep the dichromate to gum ratio constant. The scoop and my particular dichromate to colloid ratio came from Franklin Enos, a master of the casein process who got me seriously interested in alternative processes back in the late Seventies.

EMULSION COATING

I use a Korean-made HAKE brush for coating. Soft and springy, it does not abrade the paper as a foam brush may. Cheap Hake brushes tend to shed a lot and may go limp when wet. I coat under normal room lights (tungsten). The gum emulsion is brushed on quickly and left to dry for a few minutes and then the paper is hung in the dark to dry. I let it dry thoroughly because the slightly damp paper will not only adhere to the negative but the dichromate can also bleach silver emulsions! Drying should take not more than 20 minutes or so in an air-conditioned space, and it may be accelerated with a fan.

EXPOSURE

When dry, the print is placed emulsion to emulsion in contact with the “Y” negative on a light table, registered by eye, and affixed with short lengths of removable tape. Place the combination in a contact printing frame or the vacuum bed of a “plate burner” and expose for an appropriate time under UV lights - using test strips to determine proper amount of exposure.

DEVELOPMENT

Place the exposed print in a tray of slightly warm water - about 85 º F - for a minute or two. Then transfer to a second tray filled with room temperature water (70 to 80 º F). Leave it floating faced down for about 5 to 10 minutes, then check to see how it’s developing. There is a lot of leeway at this point - unless the print is grossly over or under-exposed, development is usually complete in about 10 minutes. When development is judged to be complete I give the print a quick rinse in cold water and hang it up to dry. At this point a minute amount of pigment will still run off the image, which I generally do not try to prevent since it is part of the process. If that were not acceptable, I would give it more exposure and longer development.

RED (MAGENTA) GUM

The magenta layer is made with the negative marked “M,” generated from the Green channel of the RGB. A variety of different red or magenta colors can be used. The gum mixture is the same as with the yellow. After printing this magenta layer it is possible, actually highly probable, that the color balance will be off and another printing of one of the colors would be necessary. Another printing may also be necessary for increased colors depth.

HOW I GOT STARTED

It was Phil Davis who first suggested combining cyanotype with gum. Apparently records of this kind of this combination can be traced back to the early years of the 20th century though I have never seen any of the prints - actually I have hardly ever seen any historical tri-color gum. After my initial experience of using cyanotype with gum sometime around 1990, the advantages were so obvious that I have been using this combination ever since. Phil also convinced me to mix my own gum, and introduced me to the concept of 2-color separation. Additionally, I learned BTZS system (Beyond The Zone System) from Phil, and this made me understand the whole business of sensitometry, the relationships between exposure, development, density, and contrast–a tremendous shot in the arm for both my silver work as well as the alt processes. (And it was Phil who introduced me to Franklin Enos, who did so much before his death in the mid-Eighties in getting me started with casein and gum, and Sandy King with carbon.)

WHAT ELSE DO I DO DIFFERENTLY & WHY

For single-coat processes I have never found it necessary to size the paper beforehand. At one time I did size papers for printing tri-color gum and tri-color casein but the process of sizing and hardening can be both messy and time consuming! One of the beautiful things about using cyanotype in tri-color gum is that the paper needs no additional sizing. (Did I hear a chorus of “Hallelujah”?) I always wondered why people do things that are not really necessary just because some “authority” told them to do so. I usually prefer stumbling along on my own instead of doing a lot of reading or research on others’ working methods. Only after some experience would I compare my experience with those from others. My methods consequently may be very different from those of the “gurus” but they have worked fine for me. And to me, the goal in making gum prints, or anything else, is absolutely not to just produce great- looking prints. The prints are but by-products of our search for technical and aesthetic answers, and not ends in themselves. If I were able to spell out the exact foolproof methods of making tricolor gum prints, what would be left? Cibachrome (Ilfochrome) is bright, colorful and permanent, and not hard to do at all in a closet darkroom, and it comes as a kit with foolproof instructions. But can anyone imagine making Cibachrome prints and showing them off at APIS?

There is just no one-size-fits-all way to make gum prints. I believe that the variables are too numerous for anyone to lay out a failsafe method. In fact, I’m convinced that I have just scratched the surface in terms of the potentials of this medium. Not infrequently as I go through my reject piles wondering which ones I ought to discard, the prints I rejected earlier because of some perceived technical flaws may present themselves on second consideration as beautiful, fresh, and worth keeping! What that means is that great technical command is not easy, nor absolutely necessary to make good images. Having fun doing it is crucial: “fun” in this sense is synonymous to the exhilaration of being able to ride the bicycle for the first time without falling – WOW, I’ve gained new ability and new insight! I’m addicted!

In the beginning there was the egg.

Eggs have been used as a binding medium for pigment paint since primitive times. The Temperaprint process utilises a form of light sensitive paint and has some similarities to gum bi-chromate printmaking.

The process is applied to any suitable surface in the manner of Egg-Tempera-Painting. The image is built up layer by layer, often several layers going to make a single coat, and a number of coats to make a final print.

Outline of the process

1    Have all the tools and materials you need at hand
2    Prepare the egg. Mix using a kitchen blender
3    Make a saturated solution of ammonium dichromate (SAT/SOL) with pure water, not tap
4    Make a Standard Emulsion Mix (STEM) –two parts of blended egg to one part  SAT/SOL.
5    Add colour to the STEM, approximately (depending on pigment) one part to eight (1+8).
6    Coat the Coloured Temperaprint Emulsion onto either laminated polypropylene Yupo; polyester Melamex or a heavily sized Watercolour paper. Use a plastic foam roller to coat thin/smooth.
7    Dry the coated surface with a hairdryer
8    Register the coated surface to the negative to be printed
9    Load the registered-coated surface plus negative into a contact frame
10 Expose to a light source rich in ultraviolet radiation for one to three minutes in direct sunlight
11 Develop/wash in a flat-bottomed tray containing water with a dash of dish washing up liquid added. Use a plastic foam roller to develop the image–roll gently.
12 Clear in 5% sodium metabisulphate or, better still, 1% sulphuric acid
13 Final wash
14 Dry
15 Multiple print until the desired colour/ tone is achieved

My personal aesthetic is based on the vision and writings of old Omar Khayyam and runs throughout my work as a central theme.

“For in and out, above about below.
O ‘Tis nothing but a magic shadow show.
Played in a box whose candle is the sun.
Round which we phantom figures come and go”

My phantoms are the elements of my personal world around me that I seem to perceive in a mystical way.

* WonderWall graffiti marks on walls
* Replicant {statues, dummies in windows etc}
* Passions of the night churchyards and cemeteries
* IsCream ice cream signs
* Essence digital manipulations
* Classic moody vintage images that are popular
* Metropolis city centres
* The Catalonian Connection correfoc gegantes timbalers

The footprint is of more interest to me than the foot.

BASIC CONSIDERATIONS

Let’s make a Temperaprint. First, what has to be understood from the start is that each stage in the process is precise. All work must be undertaken carefully and in a slow unhurried manner. Quantities must be measured accurately–small variations can escalate into major imaging problems. This is a process that doesn’t favour serendipity. Having said that, once in control it is a fast powerful method of imaging. Egg is very adhesive with the correct preparation–almost any surface can be printed on: paper, glass, ceramic, fabric, wood, rock, etc. It is an open ended versatile process.

Firstly, I scan a 35mm colour negative into my computer and create an electronic file. This master file is then cleaned up; all the image debris is smoothed out or removed. The overall tonal and colour balance is brought to neutral. I try to make the image on the screen as perfect as I can from a reproductive point of view. Not an easy task. Finally, I enhance the image from a creative perspective to fit my personal aesthetic.

This master file is then burnt to disk. A duplicate image is made which I colour separately in PhotoShop to give me four CMYK monochrome positive channels. I apply my PAC (see Dan Burkholder’s Making Digital Negatives for Contact Printing. Thanks Dan!) and make four inkjet negatives with register marks. I now use a superb new material from Kentmere called K Translucent II. This film gives super dense blacks said to be Dmax 4. Armed with these negatives, I am now ready to egg-tempera-print.

You may ask why I use CMYK separation rather than the more normal CMY. Well, in my image making I need to have separate control over the shadow detail.  Fine adjustment is important to me. However, this is personal taste not essential technique.

Preparing the Egg

Always use the freshest egg possible. Store-bought eggs work fine providing they are fresh. A fresh egg will have a strong sac and will form a firm mound. Over time, the sac weakens, as does the binding strength of its contents. The type of egg used can also affect binding strength. Fresh eggs from free-range chickens will produce a stronger binder because of the rich, viscous yolks.

I find that three to four eggs give enough emulsion for a three to four hour session of printmaking. I tend to work a session of this length of time firstly because I can’t work a full day any more (anno domini), and secondly the eggs go off chemically after this time and will need to be thrown away and fresh made up.

Mixing. Crack the three or four eggs into a kitchen blender, whisk for thirty seconds and you get instant consistent pure egg emulsion every time! What can be simpler than that?

To make a Saturated Solution of Ammonium dichromate

A saturated solution is where water reaches a point at which it is unable absorb any more of a dissolvable chemical, and becomes saturated. Once this condition is reached any further additions of the chemical will not be absorbed and it will just sit on the bottom of its container until further water is added. A saturated solution will always be the same, and is therefore known and constant.

You can use bottled, de-ionised, or still spa water for the purpose. The best water to use is distilled water. Never use tap water! To this water is added ammonium dichromate, which is the actual sensitizer. It is these chemicals when mixed with a colloid such as egg. that have the effect of hardening the colloid in direct proportion to the amount of light that it receives, rendering it insoluble, or tanning it, as it is sometimes described. Making a saturated solution is a very easy task. Work cleanly and keep the chemistry contained to an area that can be cleaned, and has running water, such as a sink, and wear protective/disposable gloves. Take a glass container with a sealable lid and add 100ml of pure water. To this add two heaped spoons of Ammonium Dichromate crystals and close the container. You will notice that the water turns yellow and that the crystals are sitting on the bottom, now agitate the container for thirty seconds. To check your progress let the crystals settle. The fine dust like particles will have dissolved away first, so what you should see when it clears is just the larger lump’s looking rather like sugar crystals in water. Once most of the crystals have dissolved, add another heaped spoon and continue to agitate, checking periodically on your progress. When you notice that the fine particles remain, as slurry on the bottom, and no amount of agitation will get them to dissolve, the solution is now saturated. Keeping the glass container sealed, wash under running water to remove any sensitizer that may have escaped or is trapped in the threads of the lid and clean up the area. In this saturated state the solution will last for months provided it is kept from the light in a dark brown glass container. To maintain the saturated solution, add more of the distilled water or Ammonium Dichromate, always ensuring that a fine slurry of crystals is present on the bottom.

Issues and Concerns

All chemistry can be considered potentially dangerous and therefore should be treated with respect.
1.   You should not inhale the dust
2.   Use protective or disposable gloves when mixing the sensitizer
3.   Remove any splashes on your skin immediately

STEM

STEM stands for Standard Emulsion Mix. It is a mixture primarily of the whole egg with Ammonium Dichromate, which is our sensitizer. Each part needs to be prepared separately and then brought together in the right
proportions. It is at this stage of the process that the STEM can be adjusted for a particular working characteristic. Though not complicated in any way, it should be born in mind that it is important that the measuring is done accurately for results to be consistent. To complete the STEM, measure out a 100ml of blended liquid egg into a sealable container. Now add 50ml of saturated sensitizer solution. Seal the container and agitate vigorously for ten to twenty seconds to ensure that the two liquids are fully mixed. When you open the jar you will see a frothed up orange liquid .Do not worry about this, the froth soon settles down. This is the basic STEM mix and is transferred into a measuring jug.

Adding pigment to the emulsion

I use for the moment acrylic paint in the Egg-Tempera-Print process to provide the colour; in particular, Liquitex concentrated artist colour. Other acrylics may or may not work better. Watercolour and pure ground pigment also work very well.  It is just that I like the acrylic look in the print–again, personal taste not essential technique.

Tools Materials for mixing the colour

* STEM solution
* Bottle/jar of acrylic paint [Liquitex]
* 5ml Measuring Spoon, preferably stainless steel, or a syringe without needle
* Small palette knife
* 1/2 inch brush
* Large oval white dinner plate

Take the 5ml spoon and squeeze out or pour enough paint to make a spoon full of paint. If necessary use the palette knife to level accurately. An alternative method is to use a 5ml plastic syringe.

Place the level spoonful of paint in the centre of the oval dinner plate. Now use the brush to move the paint off the spoon onto the plate. Add 5 ml of the STEM solution and begin to work the paint and STEM solution into each other until they are thoroughly uniform and mixed. Now add a further 5ml and again work them together. The important issue is to ensure as even dispersion as possible, and not to end up with clumps of pure paint sitting on the plate. Initially this means working the paint from its original stiff consistency to a liquid through a series of additions. As this progresses it will get easier to mix together as the mix becomes more and more fluid. When you have made up enough temperaprint emulsion, pour it into a small jug or beaker, then clean the plate ready for coating.

Pigment to emulsion ratio by volume

There can be few hard and fast rules as to the correct amount of pigment in the emulsion, as the variables in the supply are just too vast. Experience and getting to know your materials is the only sure way of knowing absolutely.

It is important to remember that there are two ways to change colour saturation or tonal density. One is to increase or decrease the amount of pigment in the mix. Or secondly to print a number of identical coats one on top of the other in a multiple layer approach. In practice you will tend to use a mixture of both these methods. However it is noticeable that once the ratio drops below five parts STEM solution to one part paint the working characteristics start to radically change. Coats will become heavy, exposure time will be significantly increased and the contrast will become excessive until eventually you are unable to gain a good even coat or exposure. The following provides a general guide to the limitations of how much colorant it is possible to load into a coat: -

Use one level spoonful of acrylic paint as a standard unit of measure i.e. 5ml: -

Chromatically Spoons of Emulsion (STEM)

* Strong [maximum] Four
* Medium [normal] Eight
* Thin Ten
* Glaze Twenty

Recommended CYMK ratios: K1+6, Y1+7 M1+8, C 1+15.

It is very important to measure these quantities carefully, and consistently, What has to be understood is that this coloured Temperaprint emulsion is not just some messy paint, but in fact a precise photosensitive emulsion. The amount of pigment to emulsion will vary from colour to colour.

Choice of substrate

The relationship between the emulsion or paint and the surface quality of the substrate onto which it will be laid is extremely complex. They both need to be matched very carefully. Rather like a hand snugly fitting into a glove.

As previously stated, because the egg is naturally viscous and adhesive it will coat onto any suitably prepared surface. However what has to be born in mind is it must be coated onto a surface, not into a surface. This is the fundamental difference between Gum and Egg methodology.  I have been using a laminated polypropylene plastic paper known as Yupo for the past fifteen years. I have prints on my front room gallery wall that date from 1985 that show no loss of quality. The paper facilitates a stain free surface, and is dimensionally stable, allowing an extremely accurate system of registration, thus in one stroke solving technical problems inherent in other processes. Other surfaces such polyester Melamex or a heavily sized Watercolour paper.can also be imployed as long as the egg does not impregnate the surface.

Coating the Emulsion

Take sheets of laminated plastic hard board–the sort of material that’s used in kitchens to make work tops. Place your sheet of Yupo on it with masking tape applied diagonally to the corners. Ideally this sheet of plastic should be at least twice the size of the piece of paper.

Take a four-inch acrylic foam paint roller, the sort that you can buy for use with gloss paint. Pour a measured amount of the prepared Temperaprint emulsion onto the oval plate–say from 10ml to 30ml dependent on print size. Stir the emulsion with a small brush to ensure that it is completely smooth and homogenous.

Then spread it out evenly over the surface of the plate. Place the roller on the plate; charge it up until the roller has absorbed a “generous” amount of the mix. Then roll out vigorously on clean newsprint, until it reaches a conditioned state, neither too wet nor too dry–just damp.

Start to roll down hard onto the Yupo in all directions, then slowly lighten the pressure until you are only just supporting the handle. When you begin to coat you should be firm and apply as much pressure as needed to gain the initial evenness and define your coating area. By the time you are coming to the end of the coating procedure, the only pressure should be the weight of the roller handle resting in your hand. Take your time. Let the coat just relax onto the substrate. Directly the coat looks even, stop rolling. If all has gone well, you will end up with a smooth eggshell-like finish that will expose well.

Dry the coated Surface with a hairdryer

Once you have finished laying the coat you will need to dry it prior to exposure. To do this, apply a stream of warm air over the surface at the finish of the coating process. This is most conveniently achieved using a hair dryer. When you come to this part, do not hold the hair dryer over a single spot, keep it moving. If heat is applied to a single spot you run the risk of heat fogging which, needless to say, is something that could ruin a print. Keep the hair dryer moving at all times and at least nine inches away.

From this point forward the process conforms to the outline proceedure and normal alternative print making technique:

8    Register the coated surface to the negative to be printed
9    Load the registered-coated surface plus negative into a contact frame
10 Expose to a light source rich in ultraviolet radiation one to three minutes in direct sunlight
16 Develop/wash in a flat-bottomed tray containing water, with a dash of dish washing up liquid added. Use a plastic foam roller to develop the image–roll gently.
17 Clear in 5% sodium metabisulphate or,better still, 1% sulphuric acid
18 Final wash
19 Dry
20 Multiple print until the desired colour/ tone is achieved

CMYK printmaking notes

I use a basic two coat per colour system and perhaps three with the final black printer depending on the picture aesthetic.

So with a normal CMYK print I use 8 or 9 coats. With a known image I can complete a print in three to four hours. The order of printing is:

* Black      [mars} 1+6 one coat
* Yellow   [cad lemon] 1+7 two coats
* Magenta [acra] 1+8 two coats
* Cyan     [phalo blue] 1+15 one or two coats
* Complementary further 1+8 one or two coats burnt umber or emerald green

One last point: I prefer to clear the dichromate stain with a 1% solution sulphuric acid. Acid drain clear works just as well.

Happy printmaking!

by Chris Nicholson

Some of your best photos for a given location will come not from your first visit there, but from your second, or third, or twentieth. On your first trip you may see a great waterfall, but discover that the water flow is only a trickle during the summer. On your second trip you may find that an area is filled with fields of wildflowers, but that the light angles are better at a different time of day, or even a different time of year. Each time you revisit a location, you’re likely to find a new way of photographing it, even if that new way is not immediately possible.

But remembering all those new ideas can be hard, especially if you’re in an unfamiliar region. That’s why it’s so important to take notes. You can write notes anywhere: in a pad, on the back of business cards, in a journal, on a micro-cassette recorder. Some digital cameras can even record audio notes, which you could use to save a message saying, “Try this shot again in autumn.” But I like to take my notes on maps.

Maps offer several conveniences:

I can place a note about a location right next to its place on the map. That way I have notes about weather, light, seasonal preferences and directions all in one place.

The notes are automatically filed. If I were to write notes on index cards, I’d have to somehow catalogue them by region. But because my notes are on regional maps, they’re already sorted; if I’m traveling to Maine, I just take my Maine map, and all my notes about Maine are with me, too.

It’s less to carry. I would have a map with me anyway when traveling, but if I kept my notes in a separate book, then that would be yet one more thing to bring.

Because of this system, maps are my key to second-chance photos. When I’m traveling as a photographer, I may see a landscape that would make a great photo if only the light were better, or I may see an uninspiring summer scene that would make a wonderful winter image. Or sometimes I’ll be en route to one location when I see something else that I want to shoot in the future. So I write it down on the map. Then I can use those notes to make future decisions about where and when to work.

For example, in the fall of 2000, I was photographing on a foliage assignment in Maine. While there, I stopped at Pemaquid Point Lighthouse, just east of Boothbay Harbor. I stayed for about two hours, photographing the scenic lighthouse in late-day light, and then with sunset colors in the sky. It was a good shoot. Still, after looking around the point, I knew that morning light would hit the area, too, providing opportunities for photos of a thoroughly different look and mood. I didn’t have time to stay until the next morning, so I wrote my observations about the scene in my map, for reference for the next time I had to work in Maine.

Sure enough, a year later I returned north. I saw my notes from the previous year and was able to arrange to be at Pemaquid Point at sunrise. Again I worked for two hours, creating images that, even though they were of the same subject, provided a new and different treatment than my former work there.

I use DeLorme maps for my travel photography notes. The pages are large (allowing plenty of room to write) and they’re detailed enough to show almost every road and land feature. Also, they map interesting sights common to an area: the Maine map shows lighthouses; Vermont, covered bridges; Arizona, Indian ruins. For a writing utensil, I usually carry a “space pen,” because their ink won’t freeze in cold weather and won’t smudge when printing small, like a pencil will.

by Chris Nicholson

The most important item a photographer should carry in his or her camera bag, without question, without argument, without fail, is: A camera. But after that (and some lenses, film and batteries), you’ll find that your bag still has some empty pockets to fill. Here are some suggestions for how to use that ancillary space. You’ll most likely find most of these items useful to have around.

1. Anti-Permit Gear. Have you ever been working in a U.S. national park when a ranger tells you that photography is not allowed without a permit? It happens because some park employees are confused about the rules. Photography is allowed without a permit or fee on all public federal land, as long as the photography does not involve models or non-natural props, does not damage resources, does not constitute a risk to the public, does not require extensive assistance from park personnel, does not take place in normally prohibited areas, and does not interfere with public enjoyment of the park. Print the law that says this — Public Law 106-206 — and put it in your bag. Showing it, politely, should get you off the hook.

2. Nut Driver. You know that little plastic tool that comes with some tripods so you can adjust the tension of the lever leg locks? Those tools break. Buy a nut driver that fits your locks. It will serve you well.

3. Jewelers Screwdrivers. The only tools that will fit the screws on most of your camera gear. You normally don’t want to attempt your own camera repairs, but in an emergency, Jewelers screwdrivers are the only tools that can even help you get started.

4. Film Leader Retriever. It doesn’t happen often, but it happens often enough. You put a fresh roll of film in the camera, thinking you’ll use it within a few minutes; alas, you don’t shoot again for a few hours, and the light has changed dramatically. Rather than use an inappropriate film, and rather than discard an unused (or half-used) roll, you can use your film leader retriever to save resources and money.

5. Gaffer’s Tape. An indispensable tool. Gaffer’s tape is strong but easy to tear, holds well in heat and does not leave residue. It’s also expensive, about $10 to $20 per roll. Buy some and make small rolls; re-wrap a few yards of tape onto either old film canisters, pieces of cut PVC pipe or a pencil (which nicely doubles as a writing instrument). Put them in your bag, in your vest pockets, in your car, in your luggage … everywhere. You’ll always have it when you need it to fix a lens hood, to secure a camera-strap buckle, to repair a tripod grip, etc.

6. FAA Film Regulations. Since September 11, hand-checks of film at airports have become harder to get, but Title 14 of the FAA regulations still mandates that passengers traveling with film are entitled to them. Print the regulation (also available as a PDF) so you can nicely show Section 108-209.e to inspectors who give you a hassle about this. We should expect security personnel to comply more readily now that they’re federal employees.

7. The Nikon School Handbook. Do I know how to determine exposure? To adjust for film reciprocity? To expose for a full moon? Yes. But did I ever memorize the exposure formula for determining the length of star trails? Honestly … no. That’s why I carry The Nikon School Handbook. It tells you a bunch of other stuff, too, including formulas for close-up work, tips on shooting multiple exposures, TV screens and more. It’s a great reference, and it’s small. You can get a free copy by attending Nikon School or you can buy a copy by visiting Nikon Mall. (For more information, see my Nikon School Handbook review.)

8. Shower Caps. They’ll protect your gear from rainy weather. Rain capes are better, but most photographers don’t work in the rain enough to warrant buying one. For emergencies, keep two disposable shower caps in your bag. They’re the perfect size to cover camera bodies or moderate telephoto lenses, and you can get one free every time you stay at a hotel.

9. Extra Lens Caps. When working, I usually put all my caps in the same vest pocket, but sometimes I change lenses so much in one location that I stop being organized. In the past, I’ve had to dig through all my pockets — in my photo vest, pants, shirt, jacket and bag — to find my caps again. After a couple years, I finally learned to carry extra lens caps. I bought two extra caps for each size lens I had, and I bought extra end caps, too. I put them in various pockets in my bag and in the glove box of the car. It costs only a few dollars, but the sanity you can save is priceless.

10. Ultimate Exposure Computer. Photographer Fred Parker has published a great cheat-sheet to determining exposure in any light without using a meter. It’s Old-time Knowledge 101 (based on Exposure Values), and every photographer should know it. Read the article and print the chart. I even laminated mine.

by Chris Nicholson

A significant amount of travel, landscape and nature photography involves sunrises and sunsets. And a significant amount of time to photograph these solar events involves scouting locations. Therefore, it’s important for a photographer to know how to determine not only the time of a sunrise or sunset, but also where the sun will be on the horizon (it’s almost always not due-west).

The simplest advice on this issue was once summed up in anonymous post to an online forum: “For many practical applications, the sun sets at the same time and place today as it did yesterday.”

That’s true. As long as you’re not planning to travel far in the next day, then determining sunset and sunrise times is as simple as this:

1. Today, wait for the desired solar event.
2. When it happens, note the time and the compass point of the sun’s location on the horizon.
3. Tomorrow, both will be the same.

But traveling can thwart that strategy. Moving from one side of a time zone to the other can change the time of sunset by over an hour, and moving from north to south just a few hundred miles can affect that time by 15 minutes. As for location, traveling 700 miles north or south will change the sun’s spot on the horizon by about 3°.

Therefore, having access to some tools can help photographers precisely determine specifics about sunrise and sunset.
GPS

The cost of GPS receivers has dropped dramatically in the past couple years, while the features have steadily improved. Many receivers on the market will report sunset and sunrise times for the spot you’re standing in, and the Magellan Meridian receivers offer the sun’s compass points as well.

On the web

If you have web access on the road, or if you want to prepare your research from home before you leave on a shoot, you can find sunrise and sunset data in many places on the Internet.

The Astronomical Applications Department of the U.S. Naval Observatory computes the sunrise and sunset times for either a specific day or an entire year (presented as a chart) for any location in the world. Another utility on the site will figure the position of the sun at any time of day, which you can cross-reference with the sunset or sunrise time.

If you’d like to avoid cross-referencing two utilities, try Location Works. There, a reckoner will tell you when and where the sun will rise and set for most world locations, though the user interface is more awkward than the Naval Observatory’s.

Also, the website 40-below.com doesn’t give the sun’s location, but it does give sunrise and sunset times via a convenient clickable map of the United States. At SunriseSunset.com, you can generate a calendar with the times.

The Herzberg Institute of Astrophysics has a sunrise/sunset utility that has an interesting added feature: In addition to giving the times and locations, the site can tell you the angle of sunlight for any time of day. The utility can be slightly complex to use, as not all world locations are listed (it’s mainly a Canadian service); but you can enter the latitude and longitude of any location to get the sunrise/sunset information.

Via software

If you’d like to determine sunrise and sunset date from your desktop or laptop computer, download Ephemeris 2.0 freeware from Digital Light & Color.

Another more convenient way of calculating the sunset or sunrise time in the field is by using a PDA. Several software programs meet the task handily: two are Sol! (also available in a Windows version) and Planetarium. Ephemeris 1.0 and Sun-Compass (both freeware) are similar PDA applications that also provide the sun’s location.
Explanation

If you’re really into math or astronomy (I mean really into it) and you’re interested in how all this data is determined, the U.S. Naval Observatory explains the algorithm. Good luck.

How to correct your color using RGB values
by Chris Nicholson

Part I — Part II
Part I: Prep Work

Several times people have asked me, “How can you be a photographer if you’re color blind?”

This question comes after these people learn that my eyes are particularly insensitive to the red/green areas of the spectrum. Sure, I can tell the difference between a red flower and green lily pads; I see red and green, just not the same way most of the human race does.

Still, color perception has nothing to do with how you capture an image through a lens; you see what you see, I see what I see, and if we know how to make a good exposure, then everyone’s happy.

The only problem with a colorblind photographer comes in making a print. When I was in college I knew I could never be a printer in a lab because I wouldn’t be able to accurately color-correct an image.

Alas, in the digital age, that’s no longer true. Anyone who knows how to read numbers can color-correct an image with a computer. Here’s how.

It’s a black, white and gray issue

Almost every image will have a black point and a white point — that is, a place in the photo that should be absolutely black (usually deep in a shadow) and another that should be pure white (a bright cloud, water rapids, etc.). You need to find those two points and determine the RGB value of them.

First, do a quick Levels adjustment. Move the sliders in to just barely clip the ends of the black and white ends of the histogram. Some people like to clip off more information in Levels, but I don’t like to blindly throw info away; if I want to throw out more info later, then I can do it then.

Next you need to find where in the image your black and white points are. An easy way to do this in Photoshop is to navigate through the menus to Image-Adjust-Threshold. Move the slider to the far left to see the black point, to the far right to determine the white. (You may need to nudge the slider back in from the edge to see the points.)

Cancel out of the Threshold dialog and position the mouse pointer over your black and white points. Read the RGB value for each point in the Info box, and write the values down. (Alternatively, with the Eyedropper Tool, you can shift-click on each point, which will lock the values into the Info box.)

Next, try to find something in the photo that should be gray - snow in shadow, faded cement, a gray shirt, etc. Now record the RGB value for this gray point.

(The gray point can be a lot harder to find than the black and white points - in fact, in some cases, there simply may not be any pure-gray elements of an image. In these cases, just use the black and white points.)

Part II: Correct the Color
Reset the RGB

Using Curves, you want to make the black point pure black and the white point (almost) pure white.

Open the Curves dialog (or, even better, define a Curves layer, if your image-editing software allows). What you want to do to the curve is move your earlier reading for the black point and force it to an RGB value of 0-0-0. Go to the Curve for Red and click on the black point (zero). Set your Input point as the Red reading that you recorded earlier, and leave the Output value as 0. Then do the same thing for the Green and Blue values.

By equalizing those Red, Green and Blue black-point values, you’ve now removed any color-cast at the black end of your Curve, and you’ve set the blackest point of your image to absolute black.

Next, do the same thing for your white point, except we don’t want it to be perfectly white. Pure white — i.e. 255-255-255 on the RGB scale — results in no ink being laid on the paper, which doesn’t look natural. To get some ink, but not so much that the area looks gray, we want to set the RGB value of white point to 240-240-240.

So for the white point of your image, go to the Red, Green and Blue Curves, set the Input to the values you recorded earlier, and the Output to 240. This removes any color-cast at the white end of your Curve, and produces a white that will look natural when printed.

The Gray Matter

We handle the gray point a little differently. To remove a color-cast completely, we want to set the RGB values of the gray point so they’re all the same (for example, 115-115-115; when all three RGB values are equal, that produces black, white or a shade of gray). This isn’t as straightforward as setting the black or white points.

The four most common corrections for the gray point are as follows:

1. You want the average. If the RGB values of the gray point are somewhat equally scattered (i.e., 100-116-128), calculate the average. (In this case, the average is 115.) In each of the Red, Green and Blue Curves, click in the middle of the Curve to define a point, then set the Input value to what you recorded earlier as your gray point, and your Output value to the average value that you calculated.

2. Only one color is off. If two of your RGB values are about the same but the third is way off, then you probably want to just rein in that renegade color. For example, if your gray point’s RGB value is 100-100-160, then you’re looking at a photo with a serious blue cast. In this case, try 100-100-100, or perhaps 110-110-110; try a few things to see what looks natural.

3. Why are you messing around with that color? Sometimes you don’t want to remove a color cast. A photo of early-morning mist whispering over a prairie may look better with a blue cast; a photo of late-day light falling through a canyon will certainly look better with a red cast. Your best option may be to leave the gray point alone. Or to adjust it just a little; in the previous example, adjusting that 160 Blue value to only 130 may be the perfect solution.

Gray-point is not an exact science. After color-correcting a bunch of photos, you’ll learn how to adjust your gray point, and when not to bother even trying. The point is that you learn to recognize a color-cast by looking at the RGB values rather than relying on your eye. (200-100-200 indicates a red color-cast; 100-200-100, green; and 100-100-200, blue.)

Clean Things Up

All this color-correction has likely wreaked havoc with your photo’s brightness and contrast. Use your preferred method of adjusting for those problems. I generally use the collective RGB Curve, and then I’m done. And I can go brag to my friends that I, Colorblind Chris, color-corrected a photograph.

Notes

• When setting your white point, be sure to select something that is actually white. Often a specular highlight, such as the sun shimmering through a raindrop or a bright light reflecting off metal, will show up as the whitest point in a photo, but it’s not the pure-white spot you’re looking for. Pick something that’s truly white and let the specular highlights blow out — that’s how they look best anyway.

• Your photos won’t always contain an element that’s pure gray. What to do in that situation? Eyeball it. Being red/green colorblind, this is when I usually defer to someone else’s opinion. Sisters are good for this. Another suggestion is to get a non-color-blind spouse.

• This color-correction method also works in CMYK mode; just adjust accordingly.

by Chris Nicholson

The first question many digital newcomers ask when scanning an image for computer use is: What DPI should the image be?

The answer these people usually get is: 72 DPI.

However, the correct answer is: It really doesn’t matter.

This can cause a lot of controversy, because many people — even ones who otherwise really know what they’re talking about — will insist that 72 DPI is the correct photo resolution for a computer screen. But it’s not.

I promise you: DPI is an overrated concept when it comes to images that are solely for use on a computer. If you plan to print your photo, or to send it for separation for use in a publication, then resolution is a critical detail. But if you intend to use an image only as decoration on your computer’s desktop, to post it on the Internet or to e-mail it to a friend, then you don’t even need to know what DPI is.

Look at the two photos below and try to guess the DPI value of each.

The answer: The photo on the left is 100 DPI. The photo on the right is 1 DPI. That’s not a typo; it is one DPI. Download it and see for yourself. The photos appear the same because: On a computer screen, DPI doesn’t matter.
Explanation

DPI is the abbreviation for “dots per inch.” But a monitor doesn’t know what an inch is, so how many dots are in one is irrelevant to the computer. All the monitor wants to know is the total number of dots — or pixels — that are in the image. A photo could be 5 inches wide at 100 DPI, or could be 10 inches wide at 50 DPI; either way the computer only cares that the photo is 500 pixels wide, so it can use 500 pixels to display it.

The size of an image on the monitor will then vary with how the monitor is configured. For example: Suppose you have a 17-inch monitor set to a resolution of 800X600. If you open a 400×300-pixel image, that image will take up one-quarter of the display. But if you set that same 17-inch monitor to a resolution of 1280×1024, then that same 400X300 image will fill only about one-tenth of the display. But the DPI value is never considered in these calculations, because, again: The only measurement a monitor cares about is pixel dimensions.

So the real question when scanning for the Web is: How many pixels wide and tall should I make the photo? The answer: It depends on your taste.

Just realize that the image will appear at different sizes on different computers, based on the size of the monitor and its resolution. So make it 500×500 pixels, or 50×50, or whatever you want. For my sites, I make horizontal images about 360 pixels wide, vertical images 240 pixels tall. I find that those sizes appear not too large on 800×600 monitor displays, but not too small for 1280×1024.

Why you shouldn’t pack your camera after sunset

by Chris Nicholson

A good sunset gives you opportunities to create many types of images: You can use the sunset light to warm the colors of objects on the landscape; you can silhouette objects in front of the setting sun; or you can photograph just the sun, perhaps with dramatic clouds above it. The possibilities are numerous.

But too many photographers then make this mistake: Immediately after the sun rests below the horizon, they pack their gear and leave the scene, thinking of all the wonderful sunset pictures they made. What those photographers are leaving behind are wonderful images they could have made with the light of dusk. Light bouncing off the sky or off clouds can still illuminate the ground enough for you to photograph, and the rapidly changing sky can still be a great background for silhouetted objects. Either way, always stay out shooting until all the light is gone.

This pair of photos is a good example of the benefit of shooting at dusk. The photo above is of a eucalyptus tree in front of a warm-colored sunset in New South Wales, Australia. The photo below is of another eucalyptus tree, but this time in front of a cool-colored sky in New South Wales. They look thoroughly different, but I photographed the two frames only 20 minutes apart.

That evening, after I made the first image, I almost stopped working because I was hungry and tired. But I was persistent about trying to use the post-sunset light, and my persistence was rewarded. Yes, my camera was aimed at different parts of the horizon for the two photos, but this example still shows how quickly the light can change after sunset. And it also shows the value of continuing to work even after you can no longer see the sun.

Also, remember that this same idea works in reverse at sunrise. Get to your location before dawn, and you’ll likely find a nice, cool sky to use as a background for photos you can’t get at any other time of day.

For another example, compare this photo of Smoky Mountain Sunset, which I made only half an hour before Smoky Mountain Dusk.

by Chris Nicholson

I was shooting in Maine in October 2001 and stopped at the marina of a small seaside village. I photographed some basic scenes with docks and boats and buoys, including this frame of a mooring line. But while the subject was decent enough, the light was rather flat.

Lincolnville, Maine. Nikon F5, Nikkor 80-200mm f/2.8. Photo not for sale.

Maine can be downright chilly in October, especially when the wind blows in from the Atlantic Ocean. Not much time had passed when I wondered why I was letting myself get that cold just to get some standard stock photos in less-than-inspiring light. I thought about packing up my gear and heading to the warmth of my car, but two things stopped me:

1) The photographer I was shooting with was busy working. I figured that if he was finding a way to be productive despite the flat light and the cold temperatures, then so could I.

2) Because of passing clouds, the light had been in and out all day. I looked at the sky behind me and saw that the large cloud blocking the sun was slowly blowing to the east, meaning that if I had patience, I had a chance to see some nice light.

So I decided to stay, sitting on a cold dock waiting for weather to help me. Finally the cloud passed, the light appeared, and I fired off a few frames of a nicely lit nautical landscape. The better light added warmth to the foreground, gave some color to the background, produced a shadow in the lower right corner that anchors the composition, and allowed me to get a little more depth of field (my shutter speed was limited by the motion of the dock on the waves).

Had I not waited for the better light, I still would have had the decent photo that I’d first shot. But by watching the weather and being patient, I improved my results.