Pentax 6x7 flash issues

Discussion in 'Medium Format Cameras and Accessories' started by le ninja, Jan 21, 2005.

  1. le ninja

    le ninja Member

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    Does anyone know what type of flash an FP flash is? according to the manual that type of flash can sync with the camera as fast as 1/250. the normal pc link(x) can only sync 1/30. any ideas?
     
  2. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    FP is a flash bulb that burns slowly, so that it can sync with a focal plane shutter that is never completely open. I don't know if FP bulbs are made anymore.

    Unless you want to do fill flash outdoors in bright light, you don't really need a sync speed faster than 1/30 sec.
     
  3. Nick Zentena

    Nick Zentena Member

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    A while back I saw a website selling all types of bulbs. You could almost buy a new camera for what a pocket full of bulbs would cost.
     
  4. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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  5. le ninja

    le ninja Member

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    one of the main reasons i asked is because with the pentax 6x7 the mirror shake can cause blurriness on anything slower than 1/60th. i do have the mlu model but for the purposes i am using it for the mlu feature is quite inconveinent. with the flash at 1/30 would that stop the blurriness?
     
  6. David H. Bebbington

    David H. Bebbington Inactive

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    At least one Nikon Speedlight has a mode in which it behaves like an FP flashbulb and allows flash sync with a focal-plane shutter at any shutter speed (not just the usual maximum speed for X sync.). Photographers have lost a useful resource now that there are no more flashbulbs - I seem to recall that bulb manufacturer's demonstration teams did things like photograph large public buildings (including the Great Pyramid) at night using 100 flashbulbs and more.
     
  7. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    The duration of the flash is much shorter than 1/30 sec., and in most indoor situations, the contribution to the exposure from the flash will be at least four or five stops more than ambient, so the flash will stop any motion. The effective exposure time with flash might be anywhere from 1/24000 sec. for a small shoe-mount flash at very low power to 1/300 sec. for a very powerful studio strobe unit. You only need to worry about blurring or ghosting if the ambient light level is very high relative to the flash (say if you were combining hot lights and strobes or bright daylight and strobes), or if the shutter speed is very slow, say longer than 1/8 sec.

    You can use slow sync speeds indoors to take advantage of the ambient light, but then you need to be careful about camera and subject movement (though sometimes the sharp subject with movement around it can also be interesting).

    The modern strobes that behave like FP bulbs for high-speed sync on a 35mm SLR are usually dedicated to the camera and won't work that way with non-dedicated systems. They also have the disadvantage that they can't output full power in high-speed sync mode, because they can't recycle fast enough to flash repeatedly at full power in the time it takes the slit to cross the film gate.
     
  8. ksmattfish

    ksmattfish Member

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    There is also the 90mm and 165mm leaf shutter lenses for the P67 system. They allow flash sync up to 1/500th. I have both, and they've served me well. The 90mm is no longer in production, but still available used.
     
  9. le ninja

    le ninja Member

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    thank you guys. i was really worried about it. i think i should be ok in most situations then, but just in case i'll look into that leaf shutter lens, but one thing about that..with those types of lenses doesnt the shutter have to be released on the lens?
     
  10. John Koehrer

    John Koehrer Subscriber

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    It's been a while since I actually handled the 90 but as I recall, there is no external linkage required to relase the leaf shutter. I belive the stop down linkage actually trips the leaf shutter. I don't recall on what shutter speed the camera needs to be set. Or if it matters.
     
  11. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    It sounds like it works the same way that leaf shutter lenses work on my Bronica S2A. You have to cock the leaf shutter on the lens, but the mechanism that would normally stop down the lens stops down the shutter, so you can trigger the camera in the normal way. On the Bronica you set the focal plane shutter on 1 sec. for faster leaf-shutter speeds, and B for longer leaf shutter speeds.