Negative Autochrome Film Screen in Afghan Camera with Negative Color Paper

[Mustafa Umut Sarac]

I found a idea and want to ask your opinions.

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1. 
   [*=center]First of all lets solve making autochrome screen making problem without investing tens of thousands to patent blue dye.
   [*=center]
   [*=center]I am thinking to buy a very fine quality autochrome 3''X4'' plate , than remove its bw emulsion and contact copy the autochrome RRGGBB screen on to 4x5 negative color film.
   [*=center]
   [*=center]Than c41 develop the negative color film and secure the negative at somewhere.
   [*=center]
   [*=center]Next step is to build a Afghan Camera working with color negative paper..
   [*=center]
   [*=center]Lets take out our autochrome screen copied negative film and put it in front of afghan camera's lens.

Two big question ,

What would be the final image of negative paper. Would it be a positive ?

Mustafa Umut Sarac
Istanbul​

 

[Photo Engineer]

Presumably, this would give a positive. I have said before that I had never seen an additive neg-pos system but Holmburgers posted one. So, I guess they could be made. I will have to work out the polarity-color issues before I can be sure of making a print though.

OTOH, Autochromes are so poor in quality, IDK what would result.

PE

 

[Mustafa Umut Sarac]

Thank you PE , Someone posted a stainless Afghan Camera thread and I really loved the idea. Can I develop color negative paper or film in the camera or the temperature margins are so high ?

Umut

 

[Photo Engineer]

Don't develop it in the camera. It is too corrosive.

PE

 

[Mustafa Umut Sarac]

Thank you PE , I worked at a photo house 25 years ago and inside of a cramped darkroom where thete was a automobile size paper development machine and we were working with that dinosaur. It has may be 100 liters developer inside and we breathed all the fumes.
I forgot all the details and I dont know anything about c41. Does paper development was really that corrosive ?

Umut

 

[EASmithV]

Correct me if i'm mistaken, but wouldn't the autochrome screen need to be directly contacting the film between the lens and film, not in front of the lens?

 

[Stephen Frizza]

sorry see below

 

[Stephen Frizza]

Presumably, this would give a positive. I have said before that I had never seen an additive neg-pos system but Holmburgers posted one. So, I guess they could be made. I will have to work out the polarity-color issues before I can be sure of making a print though.

OTOH, Autochromes are so poor in quality, IDK what would result.

PE

I played with this, the two main problems i had are as follows, using panchromatic black and white film you have to be careful of just how sensitive the film is to certain areas of the spectrum as it if has bias in say the yellow green the screen must accommodate this etc... tying to balance an incorrect screen to film ratio with a neg process would be a huge head ache in my opinion. Secondly the resolution is an issue. the image at 1:1 looks good but enlarging it breaks down. I think first everyone should perfect screens as a pos system then venture into neg.

 

[Stephen Frizza]

I found a idea and want to ask your opinions.


[*=center]I am thinking to buy a very fine quality autochrome 3''X4'' plate , than remove its bw emulsion and contact copy the autochrome RRGGBB screen on to 4x5 negative color film.


Mustafa Umut Sarac
Istanbul[/B]​

This Can NOT BE DONE. Autochrome plates are not RGB and the nature of the coating process in an autochrome is randomized, getting the donor registered in future tests on such a complex dispersion will be extremely difficult. This is a very bad approach.

 

[Photo Engineer]

The Autochrome process has less "quality" than the Dufay process and I am quite aware that as Autochromes (or Dufay) images are enlarged, they tend to break down and become very grainy. Evan at 1:1, an Autochrome looks worse than a Dufay image.

There are ways to balance the sensitivity of a film to a screen using color filters. This would increase the chance of success somewhat.

For useful results the screen should be against the film, but in the above OP, I can see using 2 screens. One to replicate the original and one on the print material.

PE

 

[Mustafa Umut Sarac]

Thank you all and PE.

Stephen , Could you please describe your thoughts little bit more ? You are saying Autochrome screen is not RGB , In my mind whatever this screen ever called , it can be copied from the original with a film , positively or negatively.

When it comes to register the screen film on to main film or paper can be done easily. I register two meter size emulsion transfer films less than 10 seconds with hundreth of a milimeter precision and I did may be 2000 of them.

But Stephen is talking about dispersion , this can be happen in thickness of glass plate but may be this can be replicated to put screen copy to one side of a glass and epoxy there and bw , negative , positive , color , whatever original you want to get , could be put to the other side.

See my other unanswered thread below third or forth of this thread.

Umut

 

[Mustafa Umut Sarac]

And original autochrome bw side removed plate could be used as your screen , this is for perfectionists. Read my other thread.

How color filters correct the bw emulsion , this explanation is up to our PE.

Thank you ,

Umut

 

[Photo Engineer]

If a film is high in blue and low in red sensitivity, then under daylight, one would need either more red pixels in the screen to pass more light, or one would need a red filter over the lens to block green and blue such that the overall sensitivity is neutral.

That is, provided your screen is neutral to start with.

This is a reference to something Steve posted above.

PE

 

[Stephen Frizza]

From my experience with early autochromes they are made from 4 main things potato starch dyed in green,orange-red and inky violet-purple suspended in a (lamp black) substance of pitch mixed with beeswax. the purple dye is as far as im aware Tyrian purple. this combination of dye sets required an additional orange filter to be placed upon the camra lens so the film emulsion would expose correctly allowing a 'correct' colour rendition if that makes sense?

 

[Photo Engineer]

Yep. The emulsions were "color balanced" by the user with a filter.

PE

 

[Mustafa Umut Sarac]

It doesnt diminish the value of conception.

 

[holmburgers]

Hold the phone, let's back up.

First, contact copying the roughly RGB screen of an Autochrome onto negative film would give you a reseau of CMY; not very good for separating color. Not to mention the unwanted density of the orange mask.

And, regardless, exposing through a screen onto color-negative paper would of course create a negative image on the paper. At the very best you would get a highly desaturated color negative on paper.

I do like the idea of getting a direct color print, but I'm afraid there's no easy way, and screen-plates are uniquely unsuitable for doing so. Afterall, the lack of any color is what makes white on a paper print, and a screen-plate by definition must have color all over its surface.

 

[Photo Engineer]

Well, that was one of my original objections. You cannot make an additive print process.

PE