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  1. #11
    Ole
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    Donald, that's easy if the opening is approximately round. If the opening is pentagonal, it isn't easy at all.

    Even if the aperture were perfectly round, it's not easy to measure on a 90mm SA. The difference between f:8 (11.25mm) and f:9 (10mm) can be very hard to discern.
    -- Ole Tjugen, Luddite Elitist
    Norway

  2. #12

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    I just tried this with my F8 90 and I don't seem to have any difficulty in determining the aperture size.

    However, be that as it may, I stand by my preference to measure the apparent pupil size unless of course the shutter speeds had been checked for accuracy.

    The difference between F8 and F9 represents about 1/3 stop...I tend to believe that an old unproven shutter could be off by that much or more.
    Art is a step from what is obvious and well-known toward what is arcane and concealed.

    Visit my website at http://www.donaldmillerphotography.com

  3. #13
    wiseowl's Avatar
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    Thanks, how would I measure the apparent aperture, is this what I see through the lens, or what I measure with the rear element removed?

    Thanks,

    Martin
    I'm Spartacus!

  4. #14
    Justin Cormack's Avatar
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    Mine (also in Synchro Compur) does not move past f8 and you can see a little of the blades at that, so I would go with David and suggest that the marked apeeds are right, and opening the aperture any more will have no effect as its not in the light path. Quick test is to see if it looks a stop brighter on the ground glass as you open it past f8.

  5. #15
    wiseowl's Avatar
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    Quote Originally Posted by Justin Cormack
    Mine (also in Synchro Compur) does not move past f8 and you can see a little of the blades at that, so I would go with David and suggest that the marked apeeds are right, and opening the aperture any more will have no effect as its not in the light path. Quick test is to see if it looks a stop brighter on the ground glass as you open it past f8.
    Yes it does look brighter as I open it up. So there is a problem with the aperture.

    I will now work on the basis that the scale is 1 stop out. Anyone have any ideas how to adjust it?

    Rgds

    Martin
    I'm Spartacus!

  6. #16

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    Martin,

    I have several shutterless lenses where I can open the aperture beyond the marked smallest aperture. There is also a visible change in brightness, but I noticed that the marked aperture seem to be correct to the longer exposure times I have to do (as far as those are exact timings without shutter...).

    Have you noticed an f-stop shift in your exposures? It is the result of the exposure that is important. I have not read it in your postings.

    G
    Last edited by argus; 08-20-2006 at 05:35 PM. Click to view previous post history. Reason: critical spelling

  7. #17
    David H. Bebbington's Avatar
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    I have just checked the 2 Super Angulons in my possession (90 mm in #0 Copal. 65 mm in #00 Synchro-Compur). In both cases the aperture control will move a long way past the f8 mark and at the f8 mark, the iris blades are just visible. It would appear to me that the "f8" Super Angulon would probably have a true maximum aperture of say f6.3 but that Schneider has chosen to describe it as f8 because it felt that the definition at apertures larger than f8 is not acceptable.

    Before you do anything, make some exposure tests and only send the lens for repair if the marked apertures are not giving correct exposure. I expect you will find that the marked f8 gives correct exposure. It is not uncommon for lenses to be mounted so that the maximum aperture setting does not uncover all of the glass, I expect Ole can give you plenty of examples from his collection of vintage lenses.

    Regards,

    David

  8. #18
    wiseowl's Avatar
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    Argus and David,

    thanks for the reply, I have taken a few negs with the aperture set to 1 stop wider than indicated by the meter. I've yet to process them, but will post about the results once done.

    I will say that the blades are very visible at the F8 mark, not a little bit visible. If I had a digi I would have posted an image to illistrate.

    Cheers

    Martin
    I'm Spartacus!

  9. #19
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    Just looked at mine: the f-stop lever doesn't go beyond f/8, but at that aperture there are still aperture leaves visible from the front. The lens ist from 1965.
    FWIW, Christoph

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