Ahhhhhh.... now that makes sense. I was wondering how the dye would 'bind'.Quote:
Originally Posted by Photo Engineer
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Ahhhhhh.... now that makes sense. I was wondering how the dye would 'bind'.Quote:
Originally Posted by Photo Engineer
Well, Ian, if Paul does not know, who does? The other person would be Tadeki Tani and even though I know him personally, I just can't pick up the phone and call him any old time! :D
PE
Nikola,
Remember that Gabriel Lippmann used panchromatic collodion in his early experiments with intereference color photography. Might be some clues there as well...
I do have a recipe for portrait collodion that involves flowing the plate with a mix of silver nitrate and erythrosine , but as far as I can recall, those were dry plates; and besides, my tropical collodion takes a century to set in the cold weather right now. I'll get a green and yellow filter today and try a nore systematized approach.
OK, after two days of exasperation and failure, I think I have found the optimal solution and the answer to whether or not a blind emulsion can be made ortochromatic post-coating is YES, it is possible.
The factor I had been missing was the TIME that the film soaked in the solution. I had been putting in too much dye in the emulsion and consequentially it acted as a desensitizer and actually brought the overall speed down. So, today, using a solution with a minimal amount of erythrosine and various soaking times I found the optimum for the emulsion I'm using.
I also tried to incorporate a yellow filter into the emulsion with limited success. I was using tartrazine as the yellow dye, but it let too much blue and violet in. So as a 'color screen' as described in older texts I made a collodion filter, which was then stained yellow with the same dye and seemed to let just the right amount of blue and violet in. I have access to a flatbed scanner and I'll try to scan some comparison shots in a minute.
??, here's what I have done. 6x6 cm Negatives were exposed in a Durst M707 enlarger using a 500W floodlight and then developed for a fixed amount of time( approx 3 min) in Ilford ID78 diluted 1+3.
All images were scanned without tweaks and only auto levels were applied.
It seems that the fog levels rise, possibly because of the ammonia, and the contrast is lower. I'll try a 1-5% KBr bath after before development to see it it will cut base fog levels a bit while keeping the speed.
Ammonia preliminary bath: 1 part 10% NH3 solution + 20 parts water
Ammonia + Erythrosine bath: 1part 10% NH3 + 10 parts 0.003% (300mg per 10 l) eythrosine solution
Erythrosine + Tartrasine solution: 1 part erythrosine + 50 parts tartrasine + 6000 parts H2O + 3000 parts Ethyl Alchohol
All solutions were @ 15C due to extreme cold weather and inability to adequately heat the DR
Attachment 45976
here's a color snapshot of the objects
Attachment 45977
a crop from the above images in the same succession( left to right, top to bottom)
Attachment 45987
PS: the setup may seem ridiculous but that's all I could do :P
With a blue or ortho film, the reds should show up as virtually black. If they do not, it is hard to say things are working, but my guess is that it is.
Keep going!
PE
my speculation is that without a filter the reds from the little printed spectrum are showing up due to a substantial amount of blue and near UV light reflected from the paper. Tomorrow I'll do a test with no sensitization and a yellow filter to confirm. Also, in the cropped version I just added, you can see the reds of the little semicircle do not show up in the unsensitized version.
Very impressive mon frère!
I'm definitely watching with interest..
Nikola;
Try a UV filter!
PE
