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  1. #11
    Ole
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    Stopping down is probably a good idea anyway. I noticed the difference between my various lenses when shooting within a stop or two of full aperture - so most of them were used at f:5.6!

    There was hardly any difference to be seen at f:16, which is where I take most pictures. But it might be worth noting that most lenses are not particularly well corrected for IR anyway, so some extra softness must be expected.

    One thing to look for in "soft" IR negatives is whether there is some other point which is sharper than where focus was intended. If there is, that's a strong indication that the focus should be shifted a little. If not, it won't help at all...
    -- Ole Tjugen, Luddite Elitist
    Norway

  2. #12
    JohnArs's Avatar
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    Hi Diane

    First the IR films are not as sharp as the normal ones because they are tuned for IR not for sharpness but I always work for focusshift issues in the range of f 22-64 and my negs looking really sharp an the kodak HIE wich I still have some boxes in my fridge works quit well on XTOL!

  3. #13

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    > 0.25% of 210mm is only about 0.5mm (not 5!),

    Oh crap. Now I know that I'm a total innumerate. So be it.

    --
    "The mind is always the second thing to go."

  4. #14
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    Thanks Ole. The out of focus things were in the foreground and the tree I was focusing on is in focus. I suppose I just wasn't expecting the stuff in the foreground to be that out of focus. Thanks to all who replied.
    Diane

    Halak 41

  5. #15
    KenS's Avatar
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    Quote Originally Posted by colrehogan
    Does that mean .25% times the physical distance from the lensboard to the ground glass?
    Yes.

    so..... with your 250 mm lens (at infinity), you have to "increase" the bellows distance by 1/4 of 1%. So.... it is .25 multiplied by 2.5mm = .626 mm... not a Hell of a lot. It is probably within the depth of focus. If, however, you are focussing closer than infinity then it should be the 0.25% of the focal length of the lens plus the bellows extension. Don't forget that your lens is not always the focal length marked... When "working", the 210mm Rodenstock I used to use on the Sinar P2 was "actually" a 212.5 mm focal length. The only lens with which I do not have to "make IR allowances" is my quartz/fluorite 85mm lens on my Pentax Spotmatic

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