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  1. #1
    Willie Jan's Avatar
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    Infrared photography with a TC

    Hello,

    i want to start making infrared pictures with a Crown Graphics (roll film).

    I know that i need to set it out of focus to focus sharp for the picture, but i do not know how to do this with a tc camera. My pentax mf lenses have red indicators for this, but how to deal with this with a tc?

    thanks.

  2. #2
    Ole
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    The easiest thing is to ignore it. Different lenses have different IR offsets, and you don't know how much it is for yours.

    Which film will you be using, BTW? The IR markings are for "far IR", the far end of the sensitivity of Kodak HIE. So if you're sin Konica or Maco, the correction is much less.

    Ignoring it and stopping down a couple of stops works just fine.
    -- Ole Tjugen, Luddite Elitist
    Norway

  3. #3
    Willie Jan's Avatar
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    im will be using the:
    Infrarot 820c 120 Maco

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    Ole
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    No problem then - I've used that in 4x5" without correction. I tried a slight correction too - extended about 2mm for a 210mm lens. That might be more accurate, but again it depends on the lens.

    A Tessar-type 210 was slightly sharper with 2mm extra, a 150 APO lens was sharpest without correction. Another, a 135 Planar, again was best without correction - and this was the only one I tried at full opening. Stop down to f:16 or so and I don't think you'll notice any big difference.
    -- Ole Tjugen, Luddite Elitist
    Norway

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    Willie Jan's Avatar
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    i use a schneider 135mm 4.7 lens..

    thanks for your helpfull info.

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    Ole
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    Quote Originally Posted by Willie Jan
    i use a schneider 135mm 4.7 lens..
    That will be a Xenar? Try both - "normal" focus and a slight nudge up to 1% out. That's 1.35mm, or in practical terms "a gnat's whisker".
    -- Ole Tjugen, Luddite Elitist
    Norway

  7. #7
    Willie Jan's Avatar
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    you are right, it's a Xenar. I just found a heliopan Infrared 715 filter with 40.5 mm thread that mounts this lens. Got it very cheap because nobody uses this kind of mm thread anymore....

  8. #8
    Dave Miller's Avatar
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    Quote Originally Posted by Willie Jan
    im will be using the:
    Infrarot 820c 120 Maco
    I'm with Ole here - ignore the focusing error. Your choice of film is good if you use the deep red opaque infrared filter. As a guide I rate the this film at ISO 6 in bright sunlight.
    Regards Dave.

    An English Eye


  9. #9
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    Quote Originally Posted by Willie Jan
    you are right, it's a Xenar. I just found a heliopan Infrared 715 filter with 40.5 mm thread that mounts this lens. Got it very cheap because nobody uses this kind of mm thread anymore....
    You'll have to let us know how it works for you.
    Diane

    Halak 41

  10. #10
    Willie Jan's Avatar
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    Is the bw 093 (087c) filter to high as i read somewhere on the internet to use for maco 820?

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