September 19, 2008

Van Dyke Prints: An Overview

For a little background to these overviews, see here.

History: Introduced in 1889 by Arndt and Troos, the Van Dyke print is part of a group of iron based processes which draw on Sir John Herschel's work on the Argentotype silver-iron process developed in 1842.

Negatives: A density range of about 1.5 is suitable.

Sensitizer: Part A: 9gms ferric ammonium citrate (green) + 35ml water
Part B: 1.5gms of tartaric acid + 35ml water
Part C: 12gms silver nitrate + 35ml water
In moderate light mix A, B and C (in that order) and age for a few days before use. The solution keeps well for about a year if kept in a cool, dark place. At times, owing to trace chemicals in various supplies of ferric ammonium citrate, the sensitizer may develop a muddy precipitate after about 2/3 of solution C is mixed. This can be allowed to settle and the clear sensitizer on top used, or adding about 2.5 gms more of tartaric acid can also dissolve the precipitate. The additional tartaric acid results in a fainter or no print-out image, but the developed image looks fine.

Contrast control: Contrast control can be achieved by (a) using ferric citrate in varying proportions in Part A of the sensitizer, (b) by adding about 10 drops of a 10% solution of potassium or ammonium dichromate to 500ml of the second bath during washing. (c) printing in diffused light (with perhaps a burst of direct light at the end) also subtly affects contrast. Refer to Christopher James' book for details.

Coating the paper: Use a glass rod or hake brush to coat the paper. Once the sensitizer sets, further coats can show up as streaks, so quick coating is helpful.

Printing: Print until the image appears about a stop darker than you want the final result.

Processing: (1) Wash in distilled water or tap water with a pinch of citric acid added for 5 mins. (2)Wash in running water for two mins. (Can be toned after this point). (3) Fix in 3% sodium thiosulfate solution with .2% sodium carbonate (washing soda) for about a minute, (4) followed by a final wash in running water for 30 minutes. Hang to dry. Ironing the print with a hot iron can increase the contrast slightly and change the color.

September 10, 2008

Albumen Prints: An Overview

For a little background to these overviews, see here.

History: First introduced by Louis-Desiree Blanquart-Evrard in 1850, albumen printing was the dominant photographic process for most of the second half of the nineteenth century.

Negatives: A density range of 2.0 to 2.5 is good.

Preparing the albumen: 500ml of egg whites (no yolk or white stringy bits) + 1ml glacial acetic acid + 15gm ammonium chloride + 15ml distilled water. Stir briskly until it turns into a froth. Cover container and refrigerate for 24 hrs. Remove the froth on the top and filter the liquid through cheesecloth. Age in refrigerator for a week or more.

Coating the paper: Coat by floating for 3 mins and hang to dry. To double coat, the albumen needs to be hardened. This can be done by steaming, heating to about 150F with a hot iron under a protective board, or dipping in a 500ml 70% isopropyl alcohol + 15gm ammonium chloride bath.

Sensitizing the paper: Either float, brush or use glass rod to coat with 12% silver nitrate solution under safelight. Sensitized paper does not keep well. Floating works best but results in albumen contaminating the sensitizer solution. To maintain the silver nitrate solution over a long time, add 1.5 gm kaolin per 100ml of solution. The kaolin is insoluble powder that absorbs the impurities and settles at the bottom. After every use, shake up the kaolin and let it settle overnight. Decant or siphon off clear solution before next use. Replenish the amount of solution used up with a 24% solution of silver nitrate.

Exposure: Expose until the shadows begin to bronze (maximum density) or for thinner negatives, the highlights are 1 to 1.5 stops darker than desired. Direct sun gives less contrast than diffused light.

Processing: (1) Wash 5-10mins until there is no milkiness in the running water. (Can be toned at this point). (2) Fix in 75gm sodium thiosulfate + 1gm sodium carbonate (washing soda) + 500ml water. Two fixing baths of 4mins each is recommended. (3) Immerse in 1% sodium sulfite solution for 3mins as a hypo clearing bath. (4) Wash for 30mins. Squeegee and hang to dry.

July 30, 2008

Cyanotype: An Overview


As I explore a photographic process, I will post brief summaries of its essential technical elements. These summaries are not meant to be comprehensive or to substitute for books that deal in-depth with these processes. They are more field notes for myself and might be useful for a quick lookup while working with these processes. Remember that many of these alternative processes have been around for a century and a half and more and they have evolved considerably over that time. Remember, too, that these processes were not originally meant to be used with silver or even digitally printed negatives as most modern practitioners of alternative photo processes do. There are endless variations of formulas and techniques rather than one simple "right" method as my quick overview might imply to the superficial observer. But hopefully these summaries will serve as a quick reference or encourage you to read and explore further.

History: The Cyanotype was first described by Sir John Herschel in 1842. Numerous variations on the original formula are available.

Negatives: Generally a density range of about 1.35-1.4 is okay. That is, many negatives meant for ordinary darkroom printing with diffusion enlargers can be used. I find slightly contrastier negatives with a range of about 1.5- to be more suitable when using vinegar instead of water as the developer.

Sensitizer: Solution A: 20% ferric ammonium citrate (green) solution
Solution B: 8% potassium ferricyanide solution
Store both solutions in separate bottles and mix 1:1 just before use. Solutions will keep indefinitely in sealed dark bottles. Bacteria that might grow on solution A can be filtered off.

Coating the Paper: Any non-buffered paper can be used with gelatin sizing if necessary. Alkaline environments will degrade Cyanotypes. Coat evenly with brush or glass rod under low tungsten light. Can be air dried or dried with mild heat.

Printing: Printing times can be fairly long. Check the highlights by opening the split back to see if they are a shade or two darker than you want in the print. They will lighten considerably in the wash. The shadows are not good indicators as they might begin to reverse during the printing out process.

Processing: Cyanotypes can be developed using water. But white vinegar gives slightly more midtone contrast, about a stop and a half more dynamic range and a sharper print. But vinegar tends to tint the highlights light blue instead of pure white. I have found a 1:1 mixture of white vinegar and distilled water to give the best balance between retaining highlights and a longer tonal range. Develop by agitating in a tray for 45 secs to one minute and then put in a running water wash for 5 minutes. Hang to dry. A 0.3% bath of hydrogen peroxide (1+10 sol of commonly available 3% hydrogen peroxide solution and water) just before the final wash will oxidize the print to a deep blue. This is not necessary as the print will slowly oxidize in the air as it dries, but the peroxide bath lets you see the final color at once.

Toning: Tea or coffee or tannic acid can be used to tone cyanotypes. Bleaching with a solution of one tablespoon of sodium carbonate (washing soda) per liter of water solution before toning is said to reduce staining effects but I have not yet found a satisfactory method to produce repeatable results while toning cyanotypes.

July 29, 2008

The Keepers of Light: Book Review


This book takes its subtitle - "A History and Working Guide to Early Photographic Processes" - quite seriously. It is as much a history of early photography as it is a practical guide to early processes. So, while most handbooks for these processes have a bit of history included for 'background' as a matter of course, Crawford dedicates the major chunk of the book to a detailed, sustained and quite insightful history of early photography. The practical guide to these processes is quite competent but it is almost an afterthought after the exhilarating tour-de-force of the first section of the book on the development of photography from its earliest days to well into the age of the silver gelatin print in the first half of the twentieth century.

I have always found most histories of photography to be quite tedious. They usually read like a long list of dates and developments and brief backgrounds of the persons associated with them. This approach is akin to the older sort of history as a narrative of the rise and fall of kingdoms and rulers - a history based around personalities and a more or less linear notion of progress. But Crawford takes a leaf out of newer historians who write social history not as a linear narrative but as a 'genealogy' of inter-related strands perpetually interacting with each other - 'history from below.' Of course, he isn't writing with the grand developments within academic historiography in mind, but his approach makes this a very apt comparison.

The Keepers of Light lays out the evolution of what Crawford calls the 'syntax' of photography. The first chapter uses the examples of traditional printmaking and painting very effectively to lay out what exactly constitutes a 'syntax' for a visual medium. The parallels to modern theories of linguistics and semiotics are unavoidable and Crawford uses them very effectively to illustrate his point that every visual medium has a basic 'vocabulary' and 'ordering pattern' which combine to produce a coherent 'meaning' for the observer. This can be constituted of the most basic elements like the direction and thickness of strokes in an etching or the overall formal and technical limits of a medium. And the syntax of a medium can emphasize particular elements like form, texture, tone etc at the cost of others. Crawford argues that even though photography is sometimes seen to be a medium without a syntax - a process that merely reflects the world and is therefore in a direct and 'natural' correspondence with it - in fact each particular photographic process is strictly governed by a syntax. Every detail of the process - the tone, the detail, the reproducibility, even the duration of exposure required or things like generic conventions contribute towards the syntax. Together they define the limits and possibilities of the medium, how it produces the photographic artifact and how we, as the audience, make sense of that artifact. If anything, the photographic process is so intimately tied up with technology that the limits and possibilities of the syntax must be confronted every step of the way.

Thus Crawford sets out to write a history of early photography not as a history of linear events, but as one of the evolution of the photographic syntax. Part I of the book, divided into 12 chapters, traces this evolution in terms of changing conventions, demands and technical challenges that forced nineteenth century photography to constantly develop and evolve. The result is a breathtaking history which makes the twentieth century or even the fast pace of recent change with the emergence of digital seem quite tame by comparison. In doing so, it returns the reader to the sense of awestruck wonder that the practitioners of photography or its first audiences and consumers might have felt. To capture a veritable image of the world on a sheet of paper - as if not made by man but by Nature herself - this is something the magical, awesome quality of which we have lost sight of. We with our oh-so-sophisticated cameras, 51 point autofocus and our MTF charts - even those of us who think of ourselves as 'traditionalists', use older film cameras and obsess over the zone system and sharpness. All of this is mere trifle compared to the wonder - the very sorcery - of the crude image of Paris rooftops on Niepce's bitumen covered glass. And isn't that why so many try alternative processes? To discover a hint of that magic, the discovery of the new world, the first step on the moon? It is akin to the the jaded business traveler ticking off his air miles discovering the struggle that went into man's conquest of flight - from the myth of Icarus to the Wright brothers.

And the syntax is not merely a thing-in-itself - a mere description of the technical boundaries of a process. It lives in and interacts with the world in a way an unilinear perception of 'progress' cannot grasp. Thus the Daguerrotype reigned supreme since its introduction in 1839 for a couple of decades. Technically it was capable of producing results that would satisfy the zone system or sharpness junkie of more than a century later. But there were both socio-cultural and technical demands that its syntax couldn't satisfy. Crawford traces how the more painterly rendering of the Calotype and other processes proved more pleasing to an age for which photography had not been established as a completely unique and independent medium and the reproducibility of negative images proved too strong a technical demand to resist. So the syntax moved on, it evolved, it responded to demands.

It is in conceiving of the history of photography as the history of this dialog between form and content, between demand and response that Crawford's approach is so refreshing and unique. It is full of insightful detail accompanied by vignettes and bits of humor that are all the more charming because they do not quite fit with Crawford's somber academic style. Consider for example, the following revelation: "Subjects in early daguerrotypes frequently sit with one hand supporting the chin. They look like deep thinkers: They were actually concentrating on not moving their heads" (9). Similarly delightful are his observations on the limitations imposed by technique and form on content: for example, the depopulated cityscapes in early long-exposure Calotypes, or how the exposure limitations of certain processes dictated the look of many early street photos. Amusing and astonishing, too, are vignettes about the crisis in egg supply when factories were consuming 60,000 or more eggs per day to coat albumen paper or the fact that there were studios in the 1860s churning out over 1,000 copies from a negative per day! All of this leads to a history of photography down to the period of dominance of the silver gelatin print that is truly novel in approach and eye-opening in detail.

I have spent most of this 'review' on Part I of the book. This isn't unintentional because that is the part I found most compelling. The other two parts constitute a practical guide to some of the major processes and techniques of preservation. They are chock-full of detail and great for anyone wanting to try it out, but there are relatively few illustrations and some of the materials and sources from this 1979 book have obviously fallen out of date. For a pure practical guide, perhaps more recent books like Barnier's or James' might be better, or even one of the many internet sources for quick summaries of processes. But Crawford's basic introduction to sensitometry (while a little advanced in that it tends to assume familiarity with conventional darkroom sensitometry) and technique is very helpful. In other words, buy another book if you want merely a DIY guide, but definitely read this book if you want a perspective that will change the way you look at photography - not only its past, but even its present.

Crawford, William. The Keepers of Light: A History and Working Guide to Early Photographic Processes. New York: Morgan & Morgan, 1979.

July 23, 2008

Using a DSLR as a Shutter-Tester

What good is a DSLR if you can't test the shutter of your Holga with it? Ok, I'm kidding, but there is a fairly simple way to use a DSLR as a shutter speed tester for any lens that has a leaf shutter. In fact, with a little care, this method can be used to test practically any shutter. Don't expect pinpoint accuracy or rush to put your lab equipment on eBay, but this method should be accurate to within at least a third of a stop - certainly good enough for average everyday use.

Think for a moment what a shutter does. It is simply a way to block the path of light falling on the film/sensor and then to remove that blockage for a certain known amount of time to let light fall on the film/sensor. It's a pretty simple concept really - a mechanized and repeatable version of the old hat-on-lens technique. Problem is, shutter speeds go off - they slow down, they speed up and do all sorts of funny things. Often, as in the case of mechanical marvels like the Holga, they are simply unknown, or vary from camera to camera. But if there is one good thing to be said of modern electronically controlled shutters in DSLRs and or other electronic thingamagigs, it is that they are remarkably accurate and consistent. So let's get about measuring a mechanical shutter by directly comparing it to the known shutter speeds of a DSLR.

Our first task would be to mount whatever lens/camera/shutter we want to test in front of a DSLR. Now, we don't need to focus anything or permanently mount anything. We just need to make sure that we can hold our shutter in front of the DSLR in such a way that when the shutter is closed (and the DSLR's shutter is open), no light reaches the sensor. We also, however, need to make sure that nothing sticks into the body of the DSLR so that we don't end up damaging the moving mirror. This can be done in a few ways, but the easiest for me was to use a hollow extension tube (or set of tubes) used for macro photography. I used a Nikon PK-13, mounted a BR-2a reversing ring on it and then used a simple hollow black tube that is available for less than $5 at camerafilters.com. You can use whatever you have handy - the basic idea is to provide a reasonable bit of distance between the shutter and the DSLR's body. Once done, the setup should resemble the picture on the right (I used a film body in the pictures, because I was using the digital body to make the pictures).

Now, point the whole setup towards something reasonably bright, uniform in color and preferably near middle gray in tone - a wall, the sidewalk, distant trees and the sky all work well. Nothing needs to be in focus - in fact, we want things as blurry as possible. Now the optical path has two shutters obstructing the light - the shutter to be tested, and the focal plane shutter of the DSLR. Light will reach the sensor only when both shutters are open. If we hold open either shutter in bulb mode, the other shutter's speed will be the sole determinant of the amount of light reaching the sensor. Quickly test that the optical path is truly light-tight by keeping the shutter to be tested closed and holding the DSLR's shutter open for a few seconds. If no stray light reaches the sensor, you will get a spike at the far left of the histogram as in the first histogram of the screen-capture to the right.

So now, let's put the DSLR on bulb (having a locking remote release is helpful) and fire the shutter to be tested. If you look at the resulting histogram you will see a sharp localized spike at one point. Adjust the ISO (if the lens you are testing has an aperture iris, you can also adjust that - just make sure nothing changes throughout the test) so that the spike is somewhere along the middle like the second histogram in the illustration and we are all set. Note the position of this histogram and now put the shutter on bulb and make a series of exposures with the DSLR shutter around the speed you are testing. So if you are testing to see whether the speed that says 1/100 on your shutter is accurate, then do the following:

  • Make the first exposure with the DSLR on bulb and with the shutter you are testing fired at the 1/100 setting.
  • Now, put the shutter being tested on bulb and make exposures with the DSLR at 1/200, 1/160, 1/125, 1/100, 1/80, 1/60, 1/50.
Each exposure is a third of a stop more than the previous one. If you observe the histogram, you will notice that the spike gradually travels to the right as you increase exposure. Try to pick out the one that has the spike closest to the one in the first frame - that is your shutter speed. Simple.

A word about RGB histograms. You don't need to bother with them for the test. If your subject is middle gray and your white balance is set correctly, your RGB spikes will be more-or-less at the same point, otherwise just use any of the channels or the combined histogram. In this test we are just comparing exposure times by comparing the amounts of light let in by either shutter, so as long as every other factor is consistent between those two exposures, we should do fine.

So that is it. Once you try it out, it's a pretty simple test and you should be all set to make precise exposures on Velvia with your Holga. Have fun!

June 11, 2008

Alternative Photographic Processes: A Bibliography

Here is a general bibliography on alternative photographic processes. I will keep adding to it as I come upon more resources and, over time, will put up more detailed reviews of titles I get to know well enough. If you have more suggestions to add to the list, please let me know.

Web Resources:

May 02, 2008

Where Have All the Flowers Gone, or, Why I Miss Closeups

Every photographer should try shooting nature closeups sometime! Outrageous, I know. Might as well suggest that it is the sacred duty of every budding shutterbug to make portraits of domesticated felines, or shoot oversaturated sunsets. But bear with me for a second. When I started doing photography seriously I had no interest in insects, none! Not even the more conventional interest in pretty flower shots. My foray into macro photography was the result of circumstances. I didn't have a car at the time, and I found that nature's grandeur was somewhat limited on the regular bus routes. But there was a meadow and a small lake nearby with lots of lovely plants ... and butterflies - pretty butterflies. So I tried shooting some pictures with my new zoom, but strangely not much came out. Admittedly I was a beginner all around, and my portraits or street photographs, too, were not likely to be mistaken for undiscovered Karsh or Cartier-Bresson. But y'know, if I took a shot of my friend Jack you could pretty much tell that it was my friend Jack lazing on the sofa. Same with the corner grocery store. But my shots of insects looked like I had sneezed while trying to photograph a Jackson Pollock painting - they were blurry blobs of color.

So I asked some questions on the internet, got a book, and then a couple more. Form-over-content and all that was fine, but this one needed to be cracked. An assortment of lenses and other gizmos followed and the summer saw countless rolls of film before my insects actually looked like the homely winged arthropods without artistic ambition that they were. I eventually found that while shooting at high magnifications isn't that big a deal once you got the basics right, it is nevertheless one of the most technically demanding kinds of photography that you can do with a small format camera. Closeup photography requires you to have good technique and a passing grasp of the theory. As a beginner, this can be a good thing - it's like a crash course in photographic technique. Over my first summer of doing closups, I gradually started to gain an understanding of photographic theory and technique that would perhaps have taken much longer for me to grasp otherwise. Two things in particular helped. Being on a student budget forced me to improvise and use optical gems dredged up from eBay instead of buying the latest greatest macro kit on offer that month. I found that good macro photography can be done with a wide variety of equipment, from old unloved lenses for 8mm and 16mm movie cameras to the latest macro lenses to some astoundingly expensive lenses made for scientific photography. I also made a couple of online friends whose work set the right kind of example to emulate. So, mission accomplished, I was a technically better photographer ready to move on to better things. Later, when I moved to medium and large format cameras, the transition was almost seamless because of the skills I had acquired doing macro photography manually. If you gain nothing else out of macro photography, you will gain a better understanding of photographic technique when you decide to move on. But I hope you will tarry.

That winter, I did other kinds of photography, discovering the black and white darkroom for the first time. And though it was exciting, I found I still missed the meadow. I missed waking up in the morning to catch the first bus with a bagful of gear, tripod in hand. I missed crawling on the ground, my clothes all wet and muddied, trying to get close to that dew covered hoverfly resting on the tip of a blade of grass. Making that perfectly composed and focused shot remains a thrill for every photographer, but it was much more than that that I had come to love about closups. Having grown up bang in the middle of the urban jungle, I had never really discovered nature except through the detached eyes of a "tourist." And suddenly, just under my feet, there was this whole microcosm - this whole world of beauty and color, the joy of life and the struggle, oh! the violent struggle to cling on to that life. I who had always had to look at a calendar to tell the seasons could suddenly tell what month it was from the color of the damselflies I found in the meadow! It was partly the thrill of the hunter stalking his prey, and partly the awestruck wonder of the naturalist. I think of photographing insects as wildlife photography in miniature - it requires stealth and tact. I could feel my skills at spotting camouflaged insects improve over time and with practice I managed to get closer and closer to them without causing alarm. But once you are perfectly positioned and have everything lined up, you look through the viewfinder into a vastly different world. Many of my best photographic experiences shooting insects didn't even result in successful photographs - maybe the insect flew off, maybe the breeze was too strong. But you stop caring as you almost start to communicate with that little blob of a creature climbing up a blade of grass, looking around, frantically wiping the dewdrops from its eyes and wings as it waits to catch the first rays of the sun to warm itself. At that point you no longer care about exposure or focus or sharpness or bokeh - you are merely a spectator in this minute but yet so vast theater of life.

So let me end with an old old shot that didn't work out as a photograph but was a once in a lifetime "photographic experience."

I spotted this little fella on a blade of grass and very carefully set up my tripod and got the shot framed. There was a bit of wind, so I waited. The light was also flat and I was hoping the rays of the early morning sun would add just enough punch to the photograph. The sunrays were rapidly advancing across the meadow and would be there in a few seconds, the wind was dying down as well. As I waited, I watched the little chap wipe the dew drops off its eyes as it warmed up and got ready for another day in this beautiful world that was the meadow. His every movement became immensely pronounced on my focusing screen and as I enjoyed the scene, I thought at the back of my mind how many stops might I need to compensate once the sunlight touched that blade of grass.

Soon enough, the light touched his wing and the dew drops on it sparkled, he got ready to move as soon as the light had drunk the droplets dry and I was about to trip the shutter before he did. Suddenly, out of nowhere there was a flutter and a buzz and the image in my viewfinder got blurry. It was a yellow jacket - it had probably caught a glimpse of the same sparkle that I had been waiting for and swooped in for the kill. The butterfly tried to hold on but the savagery of the wasp was indescribable. After a moment's struggle it tore its victim apart and flew away with shreds of wing and leg still sticking to the dewy grass. Even though I had been witness to this struggle I had not managed to trip the shutter.

And so I only have this serene, strangely beautiful portrait of the last moments of a butterfly in the early morning in flat light and slight wind, while waiting to make the perfect photograph. Most of us have watched the awesome fury of nature's predators on the telly - the galloping cheetah or the striking shark, but I am sure few have witnessed such fury on a cold morning in a misty meadow. So, I miss shooting closeups.

Far have I travelled, and long
At great expense, to lands unknown
To gaze across oceans, and mountains to view.

Yet my eyes have not known
But two steps from home
A blade of grass, a drop of dew.
-Rabindranath Tagore [Apologies for my hurried translation from Bengali]