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  1. #1
    holmburgers's Avatar
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    Experiments with RGB-colored screens... a la Dufaycolor & Autochrome

    Hi y'all,

    So I've posted a thorough explanation of what my proposed method is on the "autochrome recipe" thread and another older thread "restarting my autochrome experiments....". But I felt bad about hijacking these more historical discussions and thought I should just create a new thread to share my experiment/plan.

    The goal is to recreate the look of autochrome & dufaycolor photographs. Instead of attempting to reproduce these methods exactly, which were developed 103 years ago, I figured there had to be some modern methods that would be much easier.

    I came up with the idea of using slide film to record the reseau, RGB-colored screen, by photographing a white TV screen (RGB elements of equal amplitude) TV screen.

    Then, thru pin registration, this screen will be attached to ordinary panchromatic b&w film, exposed, separated, reversal processed and re-registered.

    Voila!

    Naturally, the irony is how retrogressive this technique is... using color film to make a reseau only to permit making another color picture on b&w film. .....doesn't bother me a bit though....

    So, after going thru all the theoretical steps, I've moved to the practical steps, namely, calculating magnifications. However, I've come up against some problems.

    To make a .05mm TV pixel (approx.) equal to a .005mm autochrome starch we need a magnification of 1/10th. Take a 12"x16" TV screen and 4x5" film and my calculations say that the TV can't fill the whole frame at that magnification. SOO either we have to sacrifice resolution or find a higher-definition screen.

    I haven't done the math yet, but perhaps a 1080 hi-def screen would do the trick. As I don't have one ($), a computer monitor is probably the next best thing.

    However, this got me thinking about lens/film resolution. I haven't done a ton of looking into it yet, but it seems like 60 lp/mm is about the limit of resolution.(??) That equals .017mm per line pair.

    Would it be fair to say that it's impossible to reach the resolution of the autochrome starch grains with a typical lens/film combination? I thought that making a reseau thru optical means would be significantly easier, and indeed it is, but at a cost I guess.

    I would appreciate any input on my calculations & in determining the maximum resolution available by the method I've outlined. Either way, I'm still going to attempt this.

    Thanks!

  2. #2
    holmburgers's Avatar
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    Took a couple pictures of a TV last night using EPP 4x5". I found it surprisingly difficult (at least on this set) to get a clean, blank image on the screen w/o the channel number or "no signal", etc. I had to hook up a DVD player just to get it to stop flashing at me.

    I ended up using a relatively dark screen and exposures at f/11 were 60 and 90 seconds. That's giving a 2/3 stop increase for reciprocity failure and 1 stop for bellows factor. I'm concerned with reciprocity failure and how it might affect the color balance.

    Therefore, it has occured to me that I need to use a bright white screen, which will mean shorter exposure times. Also, while looking thru a loupe and adjusting the color balance on the TV set, the phosphors didn't change color at all. So, it appears that I need a signal before I can actually manipulate the balance. The blue looked signficantly weaker than red & green did to my eye.

    Where can one find a pure white television signal? How about creating one, any ideas? You wouldn't realize how rare such a thing is until you need it!

  3. #3
    Mustafa Umut Sarac's Avatar
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    may be you need to visit your sony repair service or a video editing service. They have bunch of signal generators , ossiloscopes etc. May be your problems answers lie at electronic forums , after learning you want , you come back here.

  4. #4
    holmburgers's Avatar
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    good call on signal generators, maybe i can find some cheap somewhere. but hey, this stuff is still analog

  5. #5
    Mustafa Umut Sarac's Avatar
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    If you are talking about video signal generators , I think they are expensive. May be you can try circuit bending like musician Gazzala and blow yourself or touch 25000 volts electron tube and say goodbye to forum Or you can give a add to your weather station tv at Kansas for 5 seconds and cost you may be 1000 dollars.
    Than you photograph the tv at bulb and you get a white background and a us cloud map

  6. #6
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    It is so difficult to do that using a color dot matrix printer is much easier.

    PE

  7. #7
    Mustafa Umut Sarac's Avatar
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    Agree. if you have forced to continue at hybrid photo , I will be there and help you. May be you can connect your pc to tv via tv card and load tv with photoshop if you want to do this way. And you need flat screen tv or buy a flat screen computer monitor , may be lcd help you but I am not keen on them. But you are after specific white RGB values and for each monitor technology they are different.
    And white color is generaly 345 , ymc. I dont know the equivalent at rgb but same cmyk valus give brown , if you want grey , they must be aligned in harmonic order and different. You will be needed to real professional equipment to calibrate your monitor. I squeezed my brain and this is the post that I tried to help
    And if you want to print rgb with inkjet , you will need specific inks , you can do with getty museum formulas and they will be original otherwise you will get a autochrome with may be strange modern colors. Dont forget to add perlin noise to the screen
    Last edited by Mustafa Umut Sarac; 07-01-2010 at 06:23 PM. Click to view previous post history.

  8. #8

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    What about using a digital camera to shoot a white background,
    then hooking that up to the tv monitor?

    I cannot even begin to do the math, but large screen (outdoor) displays are another option... you might get them to give you a white screen for a few seconds before their broadcast begins

    Or just make your own...
    get ahold of some unneeded white... (or black!) studio Background Paper and
    spend the summer painting teeny tiny RGB dots on it.
    When your finished, stand back and shoot it.

    Are these good ideas, or do I need some more sleep?

  9. #9
    Mustafa Umut Sarac's Avatar
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    summer time , when the life is easy !

  10. #10
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    I'll put my two cents in here ... To create a white screen, you can always find a camcorder, small security camera, etc. that has TV output, and trick it into overexposing so far that the screen goes pure white ... maybe shine a flashlight into the lens at close distance?

    Why not shoot a computer screen (CRT or LCD) instead?

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