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  1. #1
    keithwms's Avatar
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    HDR Film / integrated exposure mask

    Alright, this is an idea I had a long time ago but I just haven't had time to work on it so I thought I'd throw it out into the ether and see what ideas people have.

    The goal is to increase the dynamic range. Yeah yeah I know it is already very large and better than digital etc. Set that aside, this has nothing to do with digital. This idea is more about making GND filters obsolete.

    The idea is to put a mask onto the film which becomes opaque with exposure. Initially, I was thinking of a photochromic material such as one finds on the "transitions" lenses. But now I wonder if there is something less expensive....

    Also, for colour film, this exposure mask would need to be as neutral as possible.

    Thoughts? Ron?
    "Only dead fish follow the stream"

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  2. #2
    markbarendt's Avatar
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    How about stacking two film's in one holder for example, 1st film (main) developed as negative 2nd film (mask) developed (less) as positive.

    Reverse the stack in the enlarger.

    Might this also work as an unsharp mask?
    Mark Barendt, Beaverton, OR

    "We do not see things the way they are. We see things the way we are." Anaïs Nin

  3. #3
    keithwms's Avatar
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    I thought of that once, Mark- to slip a pre-shot and developed neg over the new neg and thus make a light mask. That could work in principle, but registry would be a pain. And this idea is rather to have somehting that works on the fly, that you don't have to shoot twice. So perhaps if you had some sort of almost transparent layer with incorporated developer that then greys up slowly upon exposure...

    Whatever the strategy, the mask would need to be much less expensive than the photochromic materials. Perhaps there is some polaroid magic that could be invoked- a material that polarizes upon exposure or such? Where is Land when we need him!

    The advantage would be virtually limiteless dynamic range with no external filters required and no need to shoot multiple frames or do fancy processing.
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  4. #4
    BetterSense's Avatar
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    Didn't they have reusable Cibachrome masks that worked like this? I've never seen one but I always thought it was a cool idea.
    f/22 and be there.

  5. #5
    keithwms's Avatar
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    Oh I didn't know that. Hmm...
    "Only dead fish follow the stream"

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  6. #6
    markbarendt's Avatar
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    My thought was only shooting once just having "two sheets in the holder" so to speak. Lower tech than your thought.

    One thought is to use say HP5 for the main image and Delta 100 for the mask. The mask would underexpose and be aligned perfectly because it's exposed at the same time in the same holder.
    Last edited by markbarendt; 10-03-2011 at 06:05 PM. Click to view previous post history.
    Mark Barendt, Beaverton, OR

    "We do not see things the way they are. We see things the way we are." Anaïs Nin

  7. #7
    richard ide's Avatar
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    Interesting idea. the second sheet would be IIRC underexposed by 5 stops because of the AH layer on the front sheet plus whatever density the emulsion on the front sheet would add.
    Richard

    Why are there no speaker jacks on a stereo camera?

  8. #8
    keithwms's Avatar
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    I don't follow your idea, Mark- the exposed neg in the front wouldn't be cleared. Or am I missing something?

    But if there were some sort of transparent material with an integrated developer...?
    "Only dead fish follow the stream"

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  9. #9
    BetterSense's Avatar
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    Well, if you could work in a studio, you could try soaking a negative in developer, squeeging it off, and exposing it right away. The developer would exhaust in heavily exposed areas, causing massive tone compression. It might require a hole in the darkroom wall/camera obscura type setup to be workable.

    But then, if you are working in a studio, you can control the lighting....
    f/22 and be there.

  10. #10
    Lee L's Avatar
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    Contrast masking has a long history with varied uses in the wet darkroom. A quick overview is here:

    http://www.freestylephoto.biz/tradit...ntrast-masking

    As BetterSense recalls, it was nearly always used in the best Cibachrome prints shot in normal and higher contrast light.

    Lee

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