Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,337   Posts: 1,537,602   Online: 1089
      
Page 2 of 2 FirstFirst 12
Results 11 to 18 of 18
  1. #11
    Mustafa Umut Sarac's Avatar
    Join Date
    Oct 2006
    Location
    İstanbul - Türkiye
    Shooter
    35mm RF
    Posts
    3,835
    Images
    108
    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

  2. #12
    Mustafa Umut Sarac's Avatar
    Join Date
    Oct 2006
    Location
    İstanbul - Türkiye
    Shooter
    35mm RF
    Posts
    3,835
    Images
    108
    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

  3. #13
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    22,972
    Images
    65
    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

  4. #14
    Stephen Frizza's Avatar
    Join Date
    Mar 2007
    Shooter
    Medium Format
    Posts
    1,380
    Images
    174
    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?
    "Its my profession to hijack time" ~ Stephen Frizza.

  5. #15
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    22,972
    Images
    65
    Yep. The emulsions were "color balanced" by the user with a filter.

    PE

  6. #16
    Mustafa Umut Sarac's Avatar
    Join Date
    Oct 2006
    Location
    İstanbul - Türkiye
    Shooter
    35mm RF
    Posts
    3,835
    Images
    108
    It doesnt diminish the value of conception.

  7. #17
    holmburgers's Avatar
    Join Date
    Aug 2009
    Location
    Rochester NY (native KS)
    Shooter
    Multi Format
    Posts
    4,418
    Images
    2
    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.

  8. #18
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    22,972
    Images
    65
    Well, that was one of my original objections. You cannot make an additive print process.

    PE

Page 2 of 2 FirstFirst 12


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin