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Thread: 645DF+ mirror lockup and open curtain at the same time

  1. #1
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    Jun 2013
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    645DF+ mirror lockup and open curtain at the same time

    Hi all,

    I am currently in the massive time sink that is researching and deciding on my first MF Digital. So far I am leaning towards the Refub IQ160, 645DF+ and the 80LS lens combo.

    I am mostly a landscape photographer, but want to get the Leaf Shutter Lenses in case I want to dabble in Flash at a later date.

    During my web research, I came across this thread:

    Medium format Stitching, what a tough business! | Photoshop, etc.

    The poster states that "PhaseOne 645DF camera doesnít allow mirror lockup and open curtain at the same time, to let you use the lensí leaf shutter only: so that you click, and get no vibrations. Instead, the mirror can lock up as expected, but when you press the release button the second time (or use the cameraís timer) both the curtain and the leaf shutter go. According to PhaseOne customer support this is due to the way the camera has been engineered, and you have to expect vibrations in the 1/4 to 1/60 range even on a robust tripod with a solid head, due to the curtainís whiplash. "

    This is the first I have read about this and would love any help with this. Is this an issue on the 645DF+?

    Thanks in advance for any and all help


  2. #2
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    May 2008
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    Re: 645DF+ mirror lockup and open curtain at the same time

    Correct. Neither the DF nor DF+ completely disable the focal plane shutter when using the leaf shutter. The timing of the focal plane and leaf shutters however is done such that the influence of the focal plane shutter is reduced. 1/8th to 1/15th can be problematic with some lens combinations. With a proper amount of dampening (e.g. a sand bag on top of the body) this "danger zone" can be almost entirely eliminated but in practice it's usually easier to simply change aperture or ISO such that you are above or below the 1/8th to 1/15th range.

    As you'd expect a good tripod/head is important at any slower shutter speeds (which is the case regardless of platform).
    Last edited by dougpeterson; 13th September 2013 at 07:43.
    Doug Peterson , Digital Transitions | Email
    Dealer for: Phase One, Mamiya Leaf, Arca-Swiss, Cambo, Eizo, Profoto
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  3. #3
    Workshop Member Wayne Fox's Avatar
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    Nov 2009
    Draper, Utah
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    Re: 645DF+ mirror lockup and open curtain at the same time

    With MLU and the 300 on a DF, I had real problems getting a sharp image. I was wary of the 240, even with the leaf shutter because of this issue, but then tested it when I ran in Kevin Raber in Moab. I was surprised how sharp the 240 was at all speeds. So something about the timing of the FP shutter when using an LF lens definitely changes. I bought the 240LS.

    But for this and other reasons I've moved more and more to my tech camera setup. The only time I take the DF is when I need the reach of the 240 or I need to work very fast for a large variety of shots requiring a faster pace of capturing.
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