OlDoinyo Posted November 16, 2014 Share Posted November 16, 2014 When we look at what the oldest photographic gear produced, especially that used in the nineteenth century, we see certain hallmark traits that mark them as quite different from modern B&W images. Some of this difference, of course, is merely due to the aging of the materials themselves over a century or more; other characteristics may be a result of attempting to print old negatives designed for printing-out papers on modern enlarging papers, which have a very different tonal scale. However, there is something else, something intrinsic to the spectral response of old media such as wet-plate negatives which sets their output apart from that of panchromatic films or digital sensors. Wet-plate negatives used no sensitizers; the photosensitive medium was usually plain silver halide in a collodion emulsion. Developing was done in situ after exposure, under a piece of yellow glass which prevented further exposure. The lenses used did not have any modern cements or coatings, and colored filters has not yet come into use. Thus, these images probably represent a combination of blue and ultraviolet signals, with the uv/blue ratio much higher than it would have been in later materials which used sensitizers to boost visible speed. Notably, white skies are common in these old images. It therefore occurred to me that UV photography might offer an unexpected way of giving a photograph that "old" look. Here are some samples: "Old Times There are Not Forgotten." Minolta Autocord, 403 filter, Shanghai GP3. Sepia treatment added in workup. Henderson County, North Carolina. "Of the Old School." Minolta Autocord, Baader U2 filter, Ilford Delta 3200. Sepia treatment added in workup. Pope County, Minnesota. "Heaps Canyon and Zion Canyon." Olympus 35RD, 403 filter, Kodak Portra 160VC. Sepia treatment added in workup. Zion National Park, Utah. Link to comment
Alex H Posted November 16, 2014 Share Posted November 16, 2014 As far as I know, wt-plate collodion is most sensitive to ultraviolet, violet and blue. Same is true for some other aternative processes. Weather whether (I always mess up these two words) digital UV photography can truly re-create those old processes or not - I do not know, but it si an interesting subject to explore. Link to comment
nfoto Posted November 16, 2014 Share Posted November 16, 2014 UV photography using a less efficient filter than the customary Baader U2 should be able to recreate what one would capture with orthochromatic sensitised b/w in the pioneer days of photography. Combining UG5 or similar with a filter like the S8612 to curtail IR and you are there. Link to comment
baffe Posted November 17, 2014 Share Posted November 17, 2014 ...or go to paris. Under the eiffel tower you can watch a photographer taking pictures with wet colloide and processing there "in situ" for the tourists! I saw him a lot of times but only in summer. Link to comment
colinbm Posted November 17, 2014 Share Posted November 17, 2014 Interesting Clark,I had noticed that some of the UV scenes with the Sigma Foveon cameras, reminded me of family snaps with a Box Brownie, when I was a kid in the 1950s :)Col Link to comment
OlDoinyo Posted November 19, 2014 Author Share Posted November 19, 2014 An alleged spectrum of a wet plate is published here by Lund Photographics, along with commentary: http://www.lundphotographics.com/link-darkroom.html#CollodionOptics The numbers look wrong to me: we all know that UV does not begin at 462 nm, but closer to 400 nm; and the text clearly says that the plates are UV-sensitive, which is what I surmised. Link to comment
Alex H Posted November 19, 2014 Share Posted November 19, 2014 There is something strange with the scale in the picture published by Lund Photographics... Link to comment
OlDoinyo Posted February 25, 2017 Author Share Posted February 25, 2017 Postscript A better spectral response curve of wet-plate emulsion has now been posted here: https://www.flickr.com/photos/photoni/33048958715 Superimposed on a diagram for Schott glasses, it shows measurable response from 290nm to 530nm and 50% response down to 330nm (assuming linear scale.) I do not know the details of how the spectrum was obtained, but it appears to vindicate the premises of the post above. Use of antique glass lenses would of course narrow the effective response band. Link to comment
Alex H Posted February 25, 2017 Share Posted February 25, 2017 One of my large format lenses appear to transmit down to below 350 nm, but how "deep" I can not remember right now. So reaching 330-340 nm with this method should not be that difficult, depending on the illumination. Link to comment
Cadmium Posted February 25, 2017 Share Posted February 25, 2017 Clark, very nice shots. UV photography using a less efficient filter than the customary Baader U2 should be able to recreate what one would capture with orthochromatic sensitised b/w in the pioneer days of photography. Combining UG5 or similar with a filter like the S8612 to curtail IR and you are there. You can also use the same UG5 stack to shoot practically the same monochrome image as UV-only filter/stack, but with very short exposure time, as long as all you want to compare is the desaturated version.For example, can you tell which of these two desaturated shots below was shot with the Baader U and which was shot with the UG5 + S8612 stack? Of course the UG5 stack can be shot hand held.It is a good idea to test compare any two 'UV-only' filters/stacks each stacked with a GG400/GG420 first, just to see if either have any blue leak figured into the total exposure. Old secret Jedi trick. ;-)Not one I find much use for, but someone might? Link to comment
OlDoinyo Posted November 18, 2018 Author Share Posted November 18, 2018 Postscript: Ashcroft, 2015. Out of laziness I did not develop this roll of film until a couple of weeks ago. Since the film was exposed to moisture in the air, chemicals from the backing paper leached into the emulsion and imparted a texture (a known issue with Shanghai GP3 film.) As with other cases, I worked this image up in a faux-vintage manner to make the film damage seem more 'natural.' Development was in D-76 11 minutes at 20C. Camera was Minolta Autocord with Baader U2 filter; aperture probably f/11. Link to comment
photoni Posted March 16, 2020 Share Posted March 16, 2020 Postscript A better spectral response curve of wet-plate emulsion has now been posted here: https://www.flickr.c...oni/33048958715 Superimposed on a diagram for Schott glasses, it shows measurable response from 290nm to 530nm and 50% response down to 330nm (assuming linear scale.) I do not know the details of how the spectrum was obtained, but it appears to vindicate the premises of the post above. Use of antique glass lenses would of course narrow the effective response band. OIDoiny yes, it's an image of mine obtained with the overlap of three graphics I took many photos with the 1853 method on glass Wet Plate, or Tintype - Ambrotype always with 4 x 3000 Ws Elinchrome flash light ... I found this post looking for ways to reproduce the color sensitivity of wet collodion to understand the right exposure On Ebay I took a Schott BG25 filter that arrives in 10 days, I will test with my A7ii, but the ideal would be a full spectrum camera does someone who lives nearby make me take a test? (I live in Verona Italy) :))) thank you Toni Link to comment
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