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Thread: tri-color photography with oneshot camera: exposure?

  1. #11

    Join Date
    Nov 2017
    Posts
    311

    Re: tri-color photography with oneshot camera: exposure?

    The original filters are indeed marked 47, not 47b. As it is a one-shot, I can not give blue more exposure than the others unless I start adding ND filters in the red and green path.

    Ok, let's take this a bit further. Right now the filters are some non identified material that is sandwiched between 2 glass plates. Don't know what happened to it, it looks like it is delaminated (which sounds plausible after 70+ years). I guess it is a gelatin filter. The LEE filters are thin polyester ones, so I'll need to make a support for them. Right now I was thinking of making a little frame to clamp them between. Another idea was to glue them to a thin glass plate but only a single one. No idea how I'm going to avoid bubbles in that case. I'd like to find a way not to have to glue to the filters.

    IF I could find massive glass filters I'll take them but so far I haven't been able to find any. I cannot even find massive polycarbonate ones.
    Expert in non-working solutions.

  2. #12
    Drew Wiley
    Join Date
    Sep 2008
    Location
    SF Bay area, CA
    Posts
    14,144

    Re: tri-color photography with oneshot camera: exposure?

    How much exp per filter is going to be directly related to the specific film involved, the differential length of exp if recip failure set in (at long exp), and the fact that in every case, the blue separation will need significantly more exp than the R&G due to the blue filter being significantly denser. Some kind of ND option has to be in place either on the pellicles or along with the filters to get a balanced set. People who have refubished these cameras have gotten custom coated glass filters from Hoya. There are other options too, but all of them relatively expensive. You could get a filter twenty feet across if you knew where to look and had enough money. Even old Wratten gels were made in 6 inch squares.

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