Hoya RM72 - opaque?

Discussion in 'Exposure Discussion' started by David R Munson, Apr 16, 2004.

  1. David R Munson

    David R Munson Member

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    So I want to do some IR shooting using the new Maco IR film in my Nikon, and so need a suitable infrared filter. Given that you apparently need a pretty heavy filter to get good IR effect with the film, but also that I want to shoot handheld with my 50/1.2, I need to find the darkest IR-appropriate filter that isn't completely opaque. I can't tell from specs I've seen anywhere if the RM72 is just really dark or if it is actually opaque. Anyone have one of these that can tell me for sure? Thanks.
     
  2. David R Munson

    David R Munson Member

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    OK, double post time for me. Apparently the RM72 isn't totally opaque, but it is dark enough that one couldn't exactly see through it to focus, even at f/1.2. So let's tweak the question here - what is the darkest IR filter that one can actually see through to focus? I'm beginning to think that one can't really do handheld IR with the Maco stuff - if it needs something in the range of the opaque and near-opaque filters for good effect, then one can't really just stand there shooting in a vaguely normal manner. Maybe I'll stick to HIE after all...
     
  3. Ed Sukach

    Ed Sukach Member

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    The only description of the Hoya R72 - from their catalog - was, "Cuts off all light below 720 nm". I could not find a spectral transmisson curve in their literature - so I would *GUESS* that it was roughly equivalent to the more opaque (to visible light) filters.

    I use a B&W 091 (? - think?) equivalent to a Wratten #25 - dark red, but one can see through it - with MACO 820 - hand held and with tripod ... this seems to work well.

    Kodak HIE is sensitive out to 900 nm or so ... and the use of "heavily opaque" red filters (87, 89,...) is more common.
     
  4. brimc76

    brimc76 Member

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    I picked up some Maco 820 in the fall from the local Maco distributor here in Canada. They recommended using a Rodenstock RG715 filter. I haven't had a chance to use it yet but the filter sounds like your Hoya RM72. When held up to any kind of light you can just barely make out shapes. I think a focus first then attach the filter operation may be required. I have a friend that also bought this filter and I will ask him if he has any comments on it.
    I have used Kodak HIE and Konica 720 with a #25 filter for hand held with some nice results.
     
  5. glbeas

    glbeas Member

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  6. David R Munson

    David R Munson Member

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    Y'know? I always forget about that option...
     
  7. brimc76

    brimc76 Member

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    What about a Hoya #29 red Dave?
     
  8. glbeas

    glbeas Member

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    Yeah, I have that one too Dave, works pretty good with Konica 750 on my Bronica.