Wednesday, September 28, 2011

Dances with spectra ... and some famous historical figures from color photography

Sometimes an out-of-towner can encourage you to explore your own neighborhood. Here’s how Mark Fairchild acted on such encouragement.

Through a sequence of fortunate events instigated by the editor of Hue Angles, Michael Brill, I recently found myself deep in the archives of the George Eastman House International Museum of Photography and Film. Michael asked me to poke around and write something for Hue Angles on what I found.

Prior to my visit, I had to narrow the topic to provide some focus for the archivist. We decided that Lippmann photography would be of interest to many in the ISCC and I was aware that the Eastman House had several very special examples of Lippmann plates. This is where the dance with spectra began.

I was hosted by the Photo Collection Archivist, Joe Struble, who took me underneath the museum, provided wonderful conversations about old color technologies, instructed me on how to properly handle priceless photographic artifacts, and fetched the sought-after Lippmann plates from the vast underground archives. We were also joined by Mark Osterman, the Eastman House's resident guru on early photographic materials and processes. Mark discussed the Lippmann technology and shared tips for best viewing the images. One key to his instruction was that I would need to “dance with” the lighting and plates in order to line everything up just right to see some amazing spectral images. That dance also led me down a path of intersections with several historical greats in the color photography universe.

It starts at the Palais de Versailles where Gabriel Lippmann once stood with a complex camera system collecting one of the earliest spectral images ever made. I was holding the very same photographic plate that Lippmann placed in his camera doing that dance to allow essentially the same spectra present in France on that 19th-century day to fall upon my eyes. Pretty cool stuff.

The Lippmann process used an extremely fine-grain panchromatic emulsion (a black and white emulsion sensitive to all visible wavelengths) very similar to those used for holography today. The plate was placed in the camera with glass side toward the lens and then a layer of mercury was placed behind the plate to form a very good mirror in contact with the emulsion. This arrangement sets up standing light waves in the emulsion. The interference patterns were recorded as layers of exposed silver. This means the exposures essentially created interference filters at each location across the image. The plate is then viewed in white light and only the appropriate wavelengths are reflected from the stacked layers of silver in the emulsion. The result is a nearly perfect spectral reproduction of the scene. Interestingly, Lippmann won the Nobel Prize in Physics in 1908 for this invention.

The accompanying image illustrates the capture and display processes schematically. In part b, the diagonal line represents a half-silvered mirror, and the viewer is supposed to look at the leftward-going rays, which may be seen either through the depicted lens or through a prism.

The Lippmann Process
Figure reproduced from The Reproduction of Colour  by 
R.W.G.Hunt, 6th edition, published by Wiley, Chichester, 2004, figure 1.3, p. 6.

The color appearance was stunning. Dancing was indeed required to get the light, the plate, and my eyes all in the proper position, but when that tango was just right, the images were fantastic. While more light than one typically finds in a museum would have helped, it was easy to see vivid greens of foliage, purples and oranges of flowers, and a blue sky that looked accurate and not the over-saturated color we have come to expect from consumer imaging systems. Well worth the dance!

Dancing continued when we discussed the provenance of that plate and others. The plate was given to Josef Eder by Lippmann. Eder wrote the classic treatise, History of Photography, (translated into English by Edward Epstean) that includes a wonderful contemporaneous discussion of the Lippmann process. As I was shown the Eastman House copy of the book, I realized that I had that same edition on my shelf at home (passed to me by a retiring scientist). The dance continued when Eder gave his photography collection, including Lippmann’s Versailles plate, to none other than George Eastman, beneath whose wonderful home on East Avenue in Rochester the archives sit. The plate was displayed at Kodak until the museum's creation in 1949.

Other dancers in this story included Frederick Ives, his son Herbert, and Howard Wood. The Iveses had also been experimenting with the Lippmann process and a similarly interesting process based on diffraction rather than interference. I also saw some of these interference color photographs (another potentially spectral imaging system although those were trichromatic) that Ives, Ives, and Wood had perfected and patented. Several of the Lippmann plates I viewed came from the Ives family, and there were also diffractive plates that came from Wood. Frederick Ives is well known for inventing systems of trichromatic color photography, while his son Herbert is noted for developing early facsimile and television systems. Wood, their colleague at Johns Hopkins, was known for exploring fluorescence and discovering the “blacklight effect” as well as developing IR and UV photography. I will have to relive that particular dance another day. However it wrapped up with me discovering a new-to-me type of photographic process.

I will most certainly return to the archives one day--perhaps to learn more about diffractive color imaging or to explore original Kodachrome plates that were actually a two-color system (long before the time of Edwin Land). Thank you, Michael, for turning on the music for this particular dance and helping me find some new treasures in my own back yard!

-Mark D. Fairchild
Munsell Color Science Laboratory
Rochester Institute of Technology

[I wonder if Mark’s dance trope emerged from a Ph.D. trauma: Emil Wolf, who chaired his dissertation committee, queried him about spectra during his defense. The “dances with” trope and a certain movie title would be a standing wave, if not a standing ovation, in Prof. Wolf’s direction. MHB]