Saturday, November 17, 2007

photographic technology mashup

I recently had a chance to experiment with making digital negatives and using them for contact printing with platinum/palladium emulsions.

Above is a quick scan of one of the images, to give you some idea of what one looks like - although it does not do justice to the final print.

This was something I've been wanting to experiment with since I first heard about using imagesetters for this purpose, but just never got to it.

 Recently, Ron Reeder taught a workshop on the subject at Photographic Center Northwest, so I couldn't resist any longer. Given my background in digital printing and photography in general, it was an easy way to build on both of these experiences and create something new. The workshop itself was two days long - the first day covering the theory and calibration process, the second day generating negatives and printing them.

The technology is elegantly simple: you take the image you want to print, apply transfer functions to it to map its density range into the range of the print emulsion, then generate a full-sized negative onto translucent film. (Its the determination of these transfer functions, the calibration process, that adds to the complexity. But being able to do this step on a computer makes this task far easier than working with film - as photographers who used this technique in the 19th century did! I'm certainly not complaining!)

This negative is then used to make contact prints in the wet lab. For this workshop, we were using hand-applied emulsion that's sensitive to UV light - approximately 5 minute exposures, then "developed" and "cleared". This process is using chemicals I'm not used to handling in the darkroom, but which are not particularly noxious or otherwise dangerous to handle. The result after washing is an archival print, with all the smooth gradations that only a contact print makes easy, perhaps slightly soft but not in a bad way.

This same technique can be applied to other historical and modern printing processes, cyanotypes and albumen prints are something I'd like to try, and even modern silver gelatin prints can be created, with some variations. I'll probably experiment with silver a bit first, because I have to build UV light box in order to work with many of the other techniques.
I can work with silver now - I still have a functional wet lab setup (which admittedly does not get used much these days.)

A good starting point for this technology, as well as some wonderful images created using it, are available at Ron Reeder's,  site.