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Thread: Comments welcome on an errant shutter blade

  1. #1

    Comments welcome on an errant shutter blade

    I recently bought a Schneider 180mm Apo-Symmar L (new). After a while I noticed that one of the shutter blades was out of sync with the rest. In other words it appeared slightly more open than the rest. The result is that, when progressively stopped down, the shutter opening looks slightly tear-drop shape.

    The lens went back to Schneider and then to Copal. Both said that the shutter was within tolerable limits and would not affect picture quality, e.g., bokeh.

    I have no reason to doubt their word but I would like to know if a non-round shutter opening would affect the final photograph in any way.

    Many thanks.

    Steve

  2. #2

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    Re: Comments welcome on an errant shutter blade

    Yer talking about aperture blades and aperture shape, not shutter blades... right?

  3. #3

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    Re: Comments welcome on an errant shutter blade

    A shutter like a Copal never opens like an aperture but in star shape. But the time needed to open or close a shutter is always short compared with the exposure time. So it wouldn't affect the picture in any way.

    Peter K

  4. #4

    Re: Comments welcome on an errant shutter blade

    Quote Originally Posted by BrianShaw View Post
    Yer talking about aperture blades and aperture shape, not shutter blades... right?
    Sorry for the misinformation. Yes - I meant aperture blades not shutter.

    (and my apologies to Peter K as well!)

  5. #5

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    Re: Comments welcome on an errant shutter blade

    Depend on the number of aperture blades the aperture is more or less circular. E.g. the aperture of a Copal Press No. 1 is a hexagon and the aperture of a Copal 3 has 10 corners. But this doesn't influence the performance at all. Special lenses as soft focus lenses need a more circular diaphragm because this lenses uses spherical aberration for the "bokeh".

    Can you show a picture or two of the diaphragm to us?

    Cheers,
    Peter K

  6. #6

    Re: Comments welcome on an errant shutter blade

    Hello Peter,

    Sorry for the delay. I have attached a photo of the aperture. As you can see there is not much difference wide open and it would not affect image quality. However, as one stops down, it progressively gets 'worse'; although I can't imagine using f64.

    Cheers.

  7. #7
    All metric sizes to 24x30 Ole Tjugen's Avatar
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    Re: Comments welcome on an errant shutter blade

    That's not bad at all. Live with it - that's the best advice I can give you.

  8. #8

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    Re: Comments welcome on an errant shutter blade

    Steve,

    take some pictures with different f-stops and you will see there is no reason to think about the diaphragm.

    Also you can measure the transmission of the lens with an TTL exposure meter at different f-stops to dispel your doubts.

    Peter K

  9. #9

    Re: Comments welcome on an errant shutter blade

    Many thanks Peter and Ole. I shan't worry about it (but I know it will affect the resale value if I ever get rid of it - ah well). Any doubts have been put to rest. Cheers.

    Steve.

  10. #10
    ic-racer's Avatar
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    Re: Comments welcome on an errant shutter blade

    Looks like normal variation to me. I think that when examined closely, most of my lenses have some asymmetry at small apertures.

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