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Thread: I.R in 4x5

  1. #21
    msage's Avatar
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    Quote Originally Posted by JBrunner View Post
    It depends on the holders, slides and bellows. For sure the 5 bump fidelity holders are ok. Best to test rather than ruin allot of film. Concerning bellows for example, I have been told that the sheepskin on my Tachihara isn't IR safe. I will check it, of course to be sure.

    Curious how the UV in daylight relates, regarding IR?
    Hi Jason
    The bellows of my Linhof VI is safe for Efke 820, but not safe for HIE. I guess the extended sensitivity of the HIE is the difference. My older Wista is safe for both films.
    Michael

  2. #22
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    UV sensitivity in IR film

    Quote Originally Posted by JBrunner View Post

    Curious how the UV in daylight relates, regarding IR?
    Looking at the Efke/Maco poop sheet, IR film has same sensitivity curve as ordinary film, but with extended IR response. Daylight is doesn't contain a lot of IR (3 or 4 stops below visible and UV), so my guess is that IR
    films aren't any more prone to fogging in film holders than normal film, with the exception of metal darkslides exposed to heat.

    Does that make sense?

  3. #23

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    I get you David. I guess the IR effect arises principally out of those parts of the scene that emit IR - rather than the IR content of the illuminating light. And I will be sure to take my darkslides out of the oven in plenty of time before loading the holders!!!

    Thanks David
    "Why is there always a better way?"

  4. #24
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    Actually, the IR effect has nothing to do with emitted light, but rather reflected light. To see how this works, try taking a photograph of the same subject under tungsten illumination and fluorescent illumination, using an 87 IR filter, where both light sources provide an identical light meter reading at the subject location. Tungsten lights are rich in infrared; fluorescent is lacking in IR. Your subject will look quite different under the two light sources; the fluorescent-lit shot will appear significantly underexposed, if it records an image at all.

    This is why leaves of deciduous trees turn white, but the needles of conifers remain dark. Deciduous leaves are rich in chlorophyll which is a great reflector of IR. Pine needles have much less chlorophyll in them, so they do not show nearly as much IR effect.

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    Ir film

    I guess grafmatics are pretty safe, huh? Very interesting the point about pine needles and deciduous leaves.

    I find Efke IR in sheet at asa numero uno with an IR filter have not done any development tests, which of course is the only way to be certain. That is next on the schedule.

  6. #26
    Robert Hall's Avatar
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    This is not exactly true, Scott. Chlorophyll has little to do with reflectivity of IR. It is the inner cell wall which reflects the light. The amount of reflectivity has to do with the size of the cell and the systemic pressure of the cells. This is the same reason why we see the deeper layers of skin as the reflected surface with IR shots.

    This was proven by putting a leaf in a vacum, IIRC, and it became transparent under IR. I know if Helen gets ahold of this thread she could probably spread some light on the subject.

    Our skin (epidermis) has similar properties to the leaves. We have lots of dead skin cells on the upper layers, they reflect blue really well. Take a look at skin shot under blue light the take a look at the same shot in IR or deep red. The skin appears smoother with red light as it penetrates the damaged or dead layers of skin.
    Robert Hall
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  7. #27
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    Quote Originally Posted by BobNewYork View Post
    I use a Zone VI field camera and was thinking of getting me a box of EFKE and a Lee 87C filter. Anyone have any advice or know of any pitfalls I should be aware of before I embark on the quest?
    I think the Rollei IR works similarly to the Macophot. I haven't tried the Efke yet, but the 87 filter is a good choice. It takes about 1 more stop exposure than an 89b filter but it gives you a less "gimmicky" look. Here's one with the 87 filter:


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  8. #28
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    Quote Originally Posted by TheFlyingCamera View Post
    Actually, the IR effect has nothing to do with emitted light, but rather reflected light. To see how this works, try taking a photograph of the same subject under tungsten illumination and fluorescent illumination, using an 87 IR filter, where both light sources provide an identical light meter reading at the subject location. Tungsten lights are rich in infrared; fluorescent is lacking in IR. Your subject will look quite different under the two light sources; the fluorescent-lit shot will appear significantly underexposed, if it records an image at all.
    Knowledgeable and coherent. So to summarize the risk of fogging in film holders shooting outdoors, I think we can summarize and say:

    1) Foliage seems natural when shot on IR unfiltered. Only when visible is blocked do we see an effect -- and then only when we extend exposure many stops. Therefore reflected IR is only a small fraction of the total reflected light from foliage.

    2) Skies contain almost no IR (because they appear black).

    3) BobNewYork is also correct that HOT bodies emit tons of IR, and these can certainly fog IR film, but these are not normally present in a landscape scene.

    Can we safely say that IR film is no more prone to fogging when shooting a typical landscape, and that the fogging is probably do to VISIBLE light?

    If not, what are we missing?

    D.

  9. #29

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    Shmoo: That's what I'm looking for - Thanks a lot.

    David: Hear you. However, if fogging is due to visible light why the additional precautions re loading, camera type etc with IR film? Surely, if it were just the visible light then all films should be subject to the same precautions.
    "Why is there always a better way?"

  10. #30
    Ole
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    Quote Originally Posted by David William White View Post
    3) BobNewYork is also correct that HOT bodies emit tons of IR, and these can certainly fog IR film, but these are not normally present in a landscape scene.
    Only very hot bodies. At least red hot, to be precise. Just before they glow visibly red they will glow infrared, but very weakly compared to what they do when white hot.

    Things that hot are not common in landscapes, unless you're shooting volcanic eruptions or forest fires.

    Can we safely say that IR film is no more prone to fogging when shooting a typical landscape, and that the fogging is probably do to VISIBLE light?
    Sunlight is also rich in IR, and a light leak that leaks only in IR won't be visible to anything but IR film. Small insignificant light leaks also become significant when you expose for several seconds in strong light through a dark filter - remember that the light leaks are unfiltered.
    -- Ole Tjugen, Luddite Elitist
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