Focal plane distortion

Discussion in 'Ethics and Philosophy' started by cliveh, Mar 14, 2012.

  1. cliveh

    cliveh Subscriber

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  2. John Austin

    John Austin Member

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    I have never wanted to, but for the throng who does, try a Speed Graphic with FP shutter - Why does the answer still come back to SG so often?

    I have always adored this image by JHL, and the one of a child playing hoop on a cold beach with a small sailing boat on the horizon
     
  3. jnanian

    jnanian Advertiser Advertiser

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    it really can't be done with a speed graphic because 1/30 is too fast for that sort of distortion
    i have done it ( barely ) with a graflex slr, and a shutter at around 1/15S and a moving bus ( /barely )
    but never at a sports event
     
  4. Leigh B

    Leigh B Member

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    The image in the OP is typical of a vertical-travel shutter at a speed faster than its flash sync speed, i.e. when you have a moving slit and the full film aperture is never open.

    You could accomplish the same thing with any 35mm camera that uses a Copal Square shutter, like most of the second-tier Nikons of the 60's-80's(??).
    The top-of-the-line professional Nikons used horizontal-travel shutters.

    - Leigh
     
  5. ic-racer

    ic-racer Member

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    Your subject has to be moving quite fast to do it with a small format camera (because the shutter runs across the film plane pretty quick). Of course you'd want a vertical travel shutter to get the background slanted.
    porsche-lola-history-race-sports-car-1.jpg
     
    Last edited by a moderator: Mar 14, 2012
  6. jp498

    jp498 Member

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    Yeh, I'm crazy about that photo. I've got a speed graphic (pre-anniversary) to try it with, but there are so many combinations of speeds and slit widths I haven't got it yet. I've only wasted a half dozen sheets trying, so no pain no gain yet on this project. It appears Lartigue was panning the camera some and the car was moving faster than the panning motion. I want to figure it out with a box of fuji instant sometime, but the back doesn't open enough to hold the pa45. Older speed graphics go down to 1/10 sec and newer ones (with graflock back) only go down to 1/30. Not sure what difference it makes yet.
     
  7. polyglot

    polyglot Member

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    You can get this effect with any focal-plane shutter if you have a fast-enough subject. Propellers are a good start, even with very fast shutters.

    While it's not analogue, you can get crazy effects from phone-cameras with electronic shutters. They work by scanning/clearing a line of pixels at a time (sometimes quite slowly), which means you effectively have a one-pixel shutter slit, which results in very funky effects on things like propellers.
     
  8. Dan Daniel

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  9. E. von Hoegh

    E. von Hoegh Member

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  10. Ian Grant

    Ian Grant Subscriber

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    The bigger and wider the shutter the greater the effect, and older focal plane shutters that use both slit width and tension to control speed will give the greatest effect. That'll be with a narrower slit at a lower tension (curtain speed).

    Ian
     
  11. rjbuzzclick

    rjbuzzclick Member

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    I tried this myself with a Pacemaker Speed Graphic and this is the best that I got. Check out the position of her feet. I "hand-wound" the shutter slowly using the 1/1000 slit while she was turning on the merry-go-round rather quickly (she was a good sport!). The banding is from the uneven travel speed of the FP shutter slit.:
    [​IMG]
     
    Last edited by a moderator: Mar 15, 2012
  12. John Austin

    John Austin Member

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    John,
    My SG shutter goes down to 1/10th second - However, I make an assumption that the smallest slit should be set with the slowest tension - (Aperture D with Tension 1 = 1/500th sec) I have found the SG shutter to be fairly accurate

    I will take it to town today and try - Results to follow, though I really need a big road, which could we weeks away

    IMG_1593.JPG

    Anyway, I feel this is the only one way to find out
     
    Last edited by a moderator: Mar 15, 2012
  13. jnanian

    jnanian Advertiser Advertiser

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    too cool, you must have a "anniversary" .. i'm short-sighted and forgot
    that the older models had like 25 speeds ( i wish mine had 24 of'em ! )
    my pacemaker only goes to 1/30 ( only has 6 speeds ) :sad:

    have fun "Jacques Henri" :smile:

    john
     
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  15. Sirius Glass

    Sirius Glass Subscriber

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    I have tried it at the slowest shutter speeds on my Graflex Model D, but I still have not been able to reproduce the effect. [rant]Grumble, grumble, grumble [/rant]
     
  16. Leigh B

    Leigh B Member

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    Hi Sirius,

    Your shutter speed is too slow. Go back and read my post #4.

    You must use a shutter speed fast enough that the shutter aperture is a moving slit.

    - Leigh
     
  17. rjbuzzclick

    rjbuzzclick Member

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    Correct, you need a thin slit traveling at a slow speed. In my example in post #11, I was trying to reproduce the effect seen in Rober Doisneau's photo of the man and woman twisted around each other. If you look closely at her feet, and follow the line of her legs, you'll see that they're twisted oddly. It's not as great of an effect as I would have liked to get, but it's close. At some point I'll try this again and hopefully have better luck. I was using the 1/1000 slit, but "hand winding" it so it traveled across the film in about two to three seconds.

    I ran other tests using the different FP shutter speeds on my Pacemaker SG and was able to get some bending on the upright poles of the merry-go-round with smaller slit openings, but no twisting of my model as in Robert Doisneau's photo.
     
  18. Leigh B

    Leigh B Member

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    It's funny...

    I was shooting sports with a Speed Graphic in the early 1960s and tried very hard to __avoid__ this kind of distortion.

    Times change. :D

    - Leigh
     
  19. rjbuzzclick

    rjbuzzclick Member

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    Damn kids these days! Hey, get off my lawn! :smile:
     
  20. johnielvis

    johnielvis Member

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    you'd probably want a long lens too--this will also exaggerate the effect more than a shorter lens since the relative speed will be faster--relative speed is magnification times real speed
     
  21. RalphLambrecht

    RalphLambrecht Subscriber

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    i thought, yhis image was an example of horizontal shutter distortion with fast-moving subjects, which is different to focal-plane distortion.
     
  22. Leigh B

    Leigh B Member

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    Nope. Horizontal distortion stretches the subject width without distorting vertical lines.

    Think of a narrow slit moving across the film. Lines parallel to the slit will not be distorted.
    Lines perpendicular to the slit will exhibit distortion, the specifics of which depend on the direction of subject and shutter movement.

    As a shutter slit moves across the film, different areas of the film capture different points in time,
    i.e. the 1/500th sec at the top of the film is not the same time as the 1/500th sec at the bottom.

    - Leigh
     
    Last edited by a moderator: Mar 20, 2012
  23. Ian Grant

    Ian Grant Subscriber

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    It depends on what you mean by Horizontal and vertical. These older Focal plane shutters tended to have blinds that had a horizontal slit that moved vertically for the exposure, like modern Seiko SLRshutters. Older SLR's tended to use cloth shutters with a vertical slit that moved horizontally.

    When governed by tension and slit width like on a 5x4 Speed Graphic a horizontal edge of the shutter curtain slit takes just over 1/10th of a second to cross the film plane at the minimum tension #1, yet with the narrowest slit width this gives a shutter speed of 1/350th. So there's a time lag of 1/10th between the exposure at the top and at the botton, slightly longer if a wider slit is used.

    Even at the top speed of 1/1000 which is at the maximum tension #6 there's a lag of 1/35th of a second.

    Ian
     
  24. Schlapp

    Schlapp Member

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  25. Sirius Glass

    Sirius Glass Subscriber

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    I tried 1/30s, 1/25s, 1/20s, 1/15s, and 1/10s multiple times slowly panning cars move 50mph perpendicular to me at about 40 feet away using a 7 1/2" lens.
     
  26. Newt_on_Swings

    Newt_on_Swings Member

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    Moving roll film would work as well. I asked about this a bit back as well. I'll post the link for the old post when I can find it later.