John Layton
21-Apr-2015, 14:13
During my last photo teaching gig, as I was lecturing my photo-history class on N. Niepce's rightfully famous "rooftops" image, then describing how a pewter plate was first coated with bitumen of judea...then exposed for a matter of hours...then flowed with lavender oil to reveal an image - a student quickly got onto her smartphone and discovered that bitumen of judea was still available - from Amazon! Well, I just had to put in a budget request for two bottles - plus a vial of lavender oil from a local health food emporium.
Then...after doing a quick extrapolation from what would have been the aperture value of the Chevalier lens that Niepce was using, our class decided that we could get by with a one hour exposure in bright sunlight (using my 210 Sironar at f/8) - with the bitumen having been coated onto a piece of cleared 4x5 film.
The results were, well, interesting.... We did two trials, and on the second we convinced ourselves to actually see a faint outline of some of the stronger architectural details that we'd photographed. But in retrospect I'm not really all that certain what we saw. I'm also not certain that the bitumen was applied correctly (maybe I should have coated onto Pewter?), nor that my methodology, in assuming I could do a simple extrapolation to determine an exposure time, using a gooey dark substance whose response to light I am now guessing is anything but linear, was anywhere near the ballpark.
Interesting thing though - that as our class began to ponder the possibility of re-creating Niepce's technique, any amount of research into whom else might have actually tried this came up empty...which I can hardly believe. No mention of trials...successes...failures.
Could somebody please tell me that they have either tried to recreate Niepce's results, or know someone who has tried it...or that I was doing shady research and that others have tried this successfully and that documentation exists to prove it? Thanks!
Then...after doing a quick extrapolation from what would have been the aperture value of the Chevalier lens that Niepce was using, our class decided that we could get by with a one hour exposure in bright sunlight (using my 210 Sironar at f/8) - with the bitumen having been coated onto a piece of cleared 4x5 film.
The results were, well, interesting.... We did two trials, and on the second we convinced ourselves to actually see a faint outline of some of the stronger architectural details that we'd photographed. But in retrospect I'm not really all that certain what we saw. I'm also not certain that the bitumen was applied correctly (maybe I should have coated onto Pewter?), nor that my methodology, in assuming I could do a simple extrapolation to determine an exposure time, using a gooey dark substance whose response to light I am now guessing is anything but linear, was anywhere near the ballpark.
Interesting thing though - that as our class began to ponder the possibility of re-creating Niepce's technique, any amount of research into whom else might have actually tried this came up empty...which I can hardly believe. No mention of trials...successes...failures.
Could somebody please tell me that they have either tried to recreate Niepce's results, or know someone who has tried it...or that I was doing shady research and that others have tried this successfully and that documentation exists to prove it? Thanks!