Experiments with RGB-colored screens... a la Dufaycolor & Autochrome

holmburgers · Oct 27, 2010

Haha.

Experimentation then... I see

Well in my view camera I don't have a focal plane shutter nor a pressure plate. I need a junk film holder so I can carve out bigger tracks to accomodate 2 films, that might cut down on my "buckling" problem.

Swash buckling that is...

"Aye" myself. I'm tired... no more thinking today...

glbeas · Oct 27, 2010

One thing to remember is acetate film bases are not dimensionally stable. A sheet shot in register with a mask may not fit perfectly when reregistered. If the moisture content and temperature are not the same as when shot. There are mylar base films made for high dimensional stability if this is ever a problem.

holmburgers · Oct 27, 2010

Thank you Gary. I fear you're right and PE mentioned this as well. I'm soliciting Kodak films as we speak on the WTB forum, specifically for their Estar base.

Photo Engineer · Oct 27, 2010

Gary you are right.

This is why Matrix film products were coated on ESTAR. If Acetate was used, the change in size would cause misregistration and color fringing in Dye Transfer prints.

PE

Stephen Frizza · Oct 27, 2010

I thought my yellows are too green in my test hmm perhaps i will go back and try longer exposure on the RGB screen. Also if its interesting colour gamuts you want then this is the process for you as diffrent films with diffrent spectral sensitivities provide very diffrent results so does development. Also the actual colour of the Red green and blue etc... there is soooooo much variation and tweaking

michaelbsc · Oct 27, 2010

Photo Engineer said:
Gary you are right.

This is why Matrix film products were coated on ESTAR. If Acetate was used, the change in size would cause misregistration and color fringing in Dye Transfer prints.

PE

And are any films still available. I've been looking at the dye transfer group and it seems paper is popular.

Stephen Frizza · Oct 27, 2010

For those interested this is another shot of the control setup under tungsten lights

Photo Engineer · Oct 27, 2010

Steve;

As the number of filters (colors) in the beam goes up, the relative exposure increases as more light is passed. It does not necessarily correct anything but overall exposure. You have to match densities of the gray scale to make a true comparison.

PE

Mustafa Umut Sarac · Oct 27, 2010

Stephen ,

Please make a screen file and post here at 8x10 size.
Many people would like to use it.

Yes , You are right , this is an adventurous field.
I think if someone create a random plug in for photoshop to create strange colors , select few and breed with new rules program , I think this will save money.

We need a creative programs and rules.
No I dont quit film but I think computer can impress me if the programmer is smart.

I got photoshop SDK but not understand single word , may be except photoshop.

May be programming is a new field for me. Creating biological growth modelling codes are impressive and in 3D.

May be at the future , we will load our portraits to the google , add some search terms and google breed photographs. Naval Postgraduate School made a intelligent image search research at 95 with neural networks.

Biological fractals and Breen and Kurzweil painting softwares can make you quit photography.

I think I might be 30 years younger now

Stephen Frizza · Oct 27, 2010

Photo Engineer said:
Steve;

As the number of filters (colors) in the beam goes up, the relative exposure increases as more light is passed. It does not necessarily correct anything but overall exposure. You have to match densities of the gray scale to make a true comparison.

PE

Everything im doing is guess work and a shot in the dark,everything that turns out is half fluke. I have done 46 tests. Out of 46 tests I have had 7 images which loosely resemble what they should. It will need to be worked out how to either expose or process to get matching gray scales. i guess my first upload was simply to show with playing around you will be able to make a screen work.

David Grenet · Oct 27, 2010

Mustafa Umut Sarac said:
Stephen ,

Please make a screen file and post here at 8x10 size.
Many people would like to use it.

Mustafa, see my post #88 in this thread for a link to an 8x10 screen.

I hope it's useful to you,

David.

holmburgers · Oct 28, 2010

michaelbsc, all Kodak black & white films in 4x5+ are coated on Estar base (AFAIK), and I was using Ilford, so it's just a matter of switching to Kodak.

Ray Rogers · Oct 31, 2010

--------------------------------------------------------------------------------
Post 121
"the R/G/B example looks a bit dark. I think that a bit more exposure would clean it up quite a bit."

Photo Engineer said:
You have to match densities of the gray scale to make a true comparison.

PE

Can you expand on this ?

Ray Rogers · Oct 31, 2010

David Grenet said:
Mustafa, see my post #88 in this thread for a link to an 8x10 screen.

I notice some strange (to me) "happenings" when viewed going from 40% to 1000% mag. not exactly sure but color comes and goes, psychotic patterns wax and wane....

When visable, the RGB looks different from actual tricolor filters I have seen...
Should one expect them to resemble one another?

On my screen at least,
I also see white or whiteish lines or elements... any way to change them to black?

Photo Engineer · Oct 31, 2010

Ray Rogers said:
--------------------------------------------------------------------------------
Post 121
"the R/G/B example looks a bit dark. I think that a bit more exposure would clean it up quite a bit."

Can you expand on this ?

Ray;

You simply cannot compare two films with different exposures or contrasts for any definitive judgment regarding color or grain. Your visual judgment will err one way or another.

PE

holmburgers · Oct 31, 2010

Photo Engineer
You have to match densities of the gray scale to make a true comparison.

PE

Do you mean shooting a neutral step-wedge through each separation filter? For accurate color, each primary separation should have equal density throughout its contrast range.

This test would be difficult with screen plates, would it not?

Photo Engineer · Oct 31, 2010

No, I mean in the final picture. The neutral scale in the MacBeth checker should be as close to identical as possible. Then you can make a fair comparison. Otherwise you are off.

This is a fundamental concept in photo system engineering. Match the H&D curves or you are in trouble. Now, if that means that the separations need to be matched, so be it! However, Steve made one single exposure if I understand things correctly, but one image was much darker than the other and this was exposure more than anything else.

PE

holmburgers · Oct 31, 2010

Oh, ok, I gotcha now!

I need to get one of those things...

Stephen Frizza · Oct 31, 2010

Photo Engineer said:
No, I mean in the final picture. The neutral scale in the MacBeth checker should be as close to identical as possible. Then you can make a fair comparison. Otherwise you are off.

This is a fundamental concept in photo system engineering. Match the H&D curves or you are in trouble. Now, if that means that the separations need to be matched, so be it! However, Steve made one single exposure if I understand things correctly, but one image was much darker than the other and this was exposure more than anything else.

PE

Correct PE, my exposures are identical but the screens have altered density as a result of their different natures. i really want to stress that the only reason I made these screens and showed this principle can in fact work is because for so long in here so many have been talking about screens and autochrome and other Screen based colour processes I felt someone should actually do something and show something. I don't actually intend on working out the science of it and perfecting at this current time. perhaps in the future i will. I just hoped that my early efforts in making and using screens would inspire others to stop talking and start doing. So you have seen what ive done now its all your turn to play.

holmburgers · Nov 1, 2010

Stephen, I'm glad you went ahead and just did it. You knocked it out of the park and set the bar high on the first go around. Before you hang up your hat though, I'd love to see a photograph of something other than a 'test', but a real photographic use of your screen-plate. I think it's fair to say that the measure of any photo method that we come up with as technicians, is only as valuable as what we do with it as photographers.

Stephen Frizza · Nov 1, 2010

Ok I will shoot something off outdoors, a colourful landscape. I cant guarantee how its going to turn out, but it will be what it will be. give me a couple of days

holmburgers · Nov 1, 2010

awesome! looking forward to it..

David Grenet · Nov 1, 2010

Ray Rogers said:
I notice some strange (to me) "happenings" when viewed going from 40% to 1000% mag. not exactly sure but color comes and goes, psychotic patterns wax and wane....

Not there on my screen. In fact I'm quite confident that all there is in that file are alternating pixels of R, B, G in the x-axis and R, G, B in the y-axis.

What are you viewing it in? I suspect you may be seeing some artefact caused by the program you are using...

Ray Rogers · Nov 1, 2010

David Grenet said:
Not there on my screen. In fact I'm quite confident that all there is in that file are alternating pixels of R, B, G in the x-axis and R, G, B in the y-axis.

What are you viewing it in? I suspect you may be seeing some artefact caused by the program you are using...

Your probably right.

I just checked it on another computer with???
"smart screen??? and or windows image and fax viewer... standard stuff afaik nothing special... and the "strangeness", while still there, was much reduced and less "interesting".

I have not experienced changes in image based on magnification before,
Well, you know, other than size

David Grenet · Nov 1, 2010

I think it might be aliasing caused by the program's interpolation algorithm... If you zoom right in to the pixel level and then scroll you should be able to convince yourself that it is how I say. I just checked it myself and there certainly is some "strangeness" at intermediate magnifications.

Experiments with RGB-colored screens... a la Dufaycolor & Autochrome

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