View Poll Results: Would you buy & use a modern Autochrome-type film?
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The problems of Reregistration have been discussed in detail in the thread I linked to in post #68. There are several photographic examples too. When I made my first suggestion here (Post #65) I had never seen the earlier thread. Most of the things I was thinking about doing have been done and tested there. Take a look.
I saw the other thread - very interesting. Frankly, it is a long thread, and only one person (Steven Frizza, I think) put forward an example of perfect registration. I would think that the courser the screen, and the less random, the more likely registration would be possible. I think it would be extremely unlikely with as fine and as random a screen as Autochrome. I give the prize to holmburgers for his perseverance, however, in trying to come up with a system from scratch.
I guess in my little world of photography, which is very small, the goal would be to abandon computers, use true analog science, and try to create something like an Autochrome, which probably offered the best resolution of any of the screen processes. I fear that this would likely be limited to using glass plates and a screen coated thereon. I would imagine it would also be far easier to accomplish than trying to use a registration system -- except that producing a panchromatic emulsion seems to be difficult, costly, and where successful, a closely guarded secret.
I am thrilled that people including members of this thread are investing time and energy in this. As technology advances, it dumbs us down, and we lose old skills. I am glad people are keeping those skills alive.
I would probably get involved in the experimentation here is a commercially available liquid panchromatic emulsion were available, but it is not. Trying to make such a thing is way beyond my capabilities at present.
It's great seeing some good ole' screen-plate (this is the catch all phrase to describe Autochrome, Dufay, Paget, Thames, Finlay, etc., etc., etc.) discussion!
Indeed, a lot of this has been covered in that thread. Stephen Frizza has printed out a screen with an inkjet and has shown very good results. That man's the real deal. With my TV-screen idea, I've not done enough with it lately but the main problem (after I abandoned all sorts of futile attempts at using adhesives) has been re-registration; though I suspect a diagonal Condit 4x5" punch would help a lot. Unfortunately, that's an expensive and rare item and I always like the idea of everybody being able to do something, easily. The finer the screen, the harder it'll get.
Take any screen-plate and run it through a normal b&w developer and you'll get a color negative in complementary colors. The screen always needs to be RGB, but a red subject will become cyan in the negative process. If you break it down and imagine what the screen does to say, a red apple, it becomes clear why this is the case. Red light from the apple penetrates the red dye elements, which turn black/opaque when neg-dev'd; green & blue remain, voila!
The only way to make a screen-plate print on paper is something like this -> http://www.apug.org/forums/forum42/1...some-luck.html *warning, totally hypothetical*
Let's not forget this quote by Mssr. Frizza;
"Ok no offense to anyone who has posted here and I stress this is just a general comment its not directed at anyone. This thread was started on the subject of RGB screens. Why over complicate a relatively simple concept? the places this thread has gone makes me scratch my head in wonder!!! lets keep this simple concept simple! RGB screens work in their simplest form and simple works well. some of the things i have read here make it sound like people are wanting to go around the sun to meet the moon."
what about running sheet film through an inkjet printer? as long as the dyes didn't totally wash off, it'd work, right?
I've seen other threads on here re: panchromaticity/spectral sensitizing dyes and I think PE indicated that one dye cost about $100/gram. I just wonder what the early pioneers including the Lumiere brothers had to work with. Was the science that sophisticated back then? I know, I should do my own research, but I am not one who could afford $100 for 1 gram of stuff that I'd likely waste getting started.
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As some of the early colour sensitizers are food dyes they are cheap & cheerfull
Others still have medical use in testing labs so again are inexpensive and easy to find. Kodak bought Wratten to get hold of their (and Mees) expertise in this field.
Running a sheet of film through a printer presents some problems. If you put the screen on the back, then you have to expose through the AH layer. If you put it on the front, then you have to "force" development through this layer. It may or may not work. IDK.
As for sensitizing dyes, chlorophyll and erythrosine are red and green sensitizers respectively. They are inexpensive. You can make your own chlorophyll dye solution easily and erythrosine is dirt cheap from food dye sources. But, are they good dyes? No. They are usable dyes. That is why I use erythrosine as my green sensitizer. It saves money.
I think the Lumiere bro's used a dye called Orthochrome T for their red sensitivity (check out the "autochrome latex" thread). I too am really interested in knowing about early sensitizers, particularly for red. Ron has showed that erythrosine is a decent green sensitizer, but red has remained elusive at similar prices. I plan to resurvey some of the early efforts (Vogel, Lippmann, Ives, etc.) and see if there's a good candidate somewhere.
Ian, do you have any specific recommendations by chance? A biological stain would be ideal.
Chlorophyll has always interested me, and the method of preparation sounds so simple; soaking blue myrtle or spinach leaves in alcohol. But everyone usually agrees that it's not consistent enough from batch to batch to be usable, and so it's remembered as a curiousity and not investigated.
However, a lot has changed since the late 1800's. Chlorophyll molecules can now be synthesized and are used for a variety of things from food coloring to herbal "remedies". Wiki says, "Extracted liquid chlorophyll was considered to be unstable and always denatured until 1997, when Frank S. & Lisa Sagliano used freeze-drying of liquid chlorophyll at the University of Florida and stabilized it as a powder, preserving it for future use."
More about chrolophyll.
Chlorophyllin is known as "Natural Green 3", food additive code E141 and quote, "Because natural chlorophyll is not as stable as chlorophyllin and is much more expensive, most over-the-counter chlorophyll supplements actually contain chlorophyllin."
So in other words, we now have access to a much more stable and water soluble form of chlorophyll. Interesting...
Last edited by holmburgers; 04-30-2012 at 12:19 PM. Click to view previous post history.
Reason: added a bit
OTOH, Chlorophyll is a rather poor sensitizing dye in terms of efficiency and in terms of spectral response. A true red sensitizing dye is cyan in color and not green.
I guess I am still in theoretical mode here in deciding whether to jump in and invest in some experiments. My view of the autochromes I have seen on the internet (e.g. the French government site of WW1 autochromes) is that they are awesome regardless of the fact that colors are not accurate. I think I would be more attracted to using, as PE says, a "useable dye" rather than something that guarantees accuracy (after much experimentation by a layman like me) at great cost.
Think of it this way: After all the threads and very interesting experimentation here using computer screens, attempts at registration, screen duplication using reversal film, etc -- what are the odds of getting a halfway decent result by dying starch, coating a glass plate and sealing it, re-coating with an emulsion sensitized with home made chlorophyll and cheap green sensitizer, and taking a picture? I bet it would be a lot easier to get relatively repeatable results, even if at the sacrifice of accuracy, which itself may not be necessary in achieving an awesome result.
I know I am just hypothesizing and I am a long way off of experimenting with emulsion coating (although I am tempted to make some chlorophyll and add it to some Liquid Light). But the steps involved above seem intuitively simpler than many of the other things discussed here, especially those involving registration.