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Thread: Copal 0 shutter accuracy

  1. #21
    Drew Wiley
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    Re: Copal 0 shutter accuracy

    I test all my shutters in advance with a Calumet electronic tester. This involves multiple readings for sake of predictability at any given speed, which is more important than nominal speed accuracy. Any slight deviation from the norm can be put on a lensboard label for sake of fussy applications like color chrome film. Every one of my Copal shutters of any size or vintage has been well within a third stop at every typically used speed, and generally even more accurate than that. But not a single one of those shutters, even brand new, was even remotely close to accurate at the very highest speed (typically 1/500th). I once had a Compur 3 which was spot on over the entire range, but disliked it for other reasons. Studio photographers were more concerned with flash speed synch, while people like me don't give a damn about the top speeds anyway, at least for view camera use.

  2. #22
    Alan Klein's Avatar
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    Re: Copal 0 shutter accuracy

    Quote Originally Posted by Drew Wiley View Post
    I test all my shutters in advance with a Calumet electronic tester. This involves multiple readings for sake of predictability at any given speed, which is more important than nominal speed accuracy. Any slight deviation from the norm can be put on a lensboard label for sake of fussy applications like color chrome film. Every one of my Copal shutters of any size or vintage has been well within a third stop at every typically used speed, and generally even more accurate than that. But not a single one of those shutters, even brand new, was even remotely close to accurate at the very highest speed (typically 1/500th). I once had a Compur 3 which was spot on over the entire range, but disliked it for other reasons. Studio photographers were more concerned with flash speed synch, while people like me don't give a damn about the top speeds anyway, at least for view camera use.
    Drew, Who do you send them to to calibrate? Cost?

  3. #23
    Drew Wiley
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    Re: Copal 0 shutter accuracy

    I bought my own testing machine, Alan. Perhaps there are still shutter testers around for sale used; but the instructions for different kinds of shutters must be carefully followed. Otherwise, a lens service like S.K.Grimes could no doubt do it.

  4. #24

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    Re: Copal 0 shutter accuracy

    Drew makes a point that I neglected: The fastest speeds on clockwork shutters are never close, but it makes very little difference in practice since the fastest speeds are rarely, if ever, used. I don't think I've ever made a large-format photograph with natural light at a speed higher than 1/60th second. It's the slower speeds that need to be reasonably accurate.

    Another consideration: when shutter speeds vary much from what they are marked, they are usually slower. That bit of extra exposure on negative film makes absolutely no difference in practice. You only really need to worry about being really precise when using transparency film. For that, testing actual speeds and making a label does the job superbly.

    Best,

    Doremus

  5. #25

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    Re: Copal 0 shutter accuracy

    Cannot remember needing or using the shutter speed of 1/120 second for the many, many thousands of 5x7 & 13x18cm & 4x5 & 6x9-6x7cm film images ever.

    IMO, shutter speeds above 1/60 second for sheet film and larger format tool film is not an issue. The slower speeds below one second is more important.
    If there is too much light to achieve the needed film exposure, add neutral density filter., which has also been as rare as needing shutter speeds of 1/120 second or higher.

    For 35mm or Digital, 1/4000 or 1/8000 at times is not fast enough.


    Bernice

  6. #26

    Re: Copal 0 shutter accuracy

    I suppose one more question would be just what to you plan to do with LF transparencies (other than look at it once and say "oh, neat") that wouldn't better be done with negative film?

  7. #27

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    Re: Copal 0 shutter accuracy

    Quote Originally Posted by Chauncey Walden View Post
    I suppose one more question would be just what to you plan to do with LF transparencies (other than look at it once and say "oh, neat") that wouldn't better be done with negative film?
    That’s about it...

  8. #28
    Tin Can's Avatar
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    Re: Copal 0 shutter accuracy

    Same as any picture!
    sin eater

  9. #29
    Alan Klein's Avatar
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    Re: Copal 0 shutter accuracy

    Quote Originally Posted by Doremus Scudder View Post
    Drew makes a point that I neglected: The fastest speeds on clockwork shutters are never close, but it makes very little difference in practice since the fastest speeds are rarely, if ever, used. I don't think I've ever made a large-format photograph with natural light at a speed higher than 1/60th second. It's the slower speeds that need to be reasonably accurate.

    Another consideration: when shutter speeds vary much from what they are marked, they are usually slower. That bit of extra exposure on negative film makes absolutely no difference in practice. You only really need to worry about being really precise when using transparency film. For that, testing actual speeds and making a label does the job superbly.

    Best,

    Doremus
    The shutter speeds up to 1/30th I checked were about 1/3 stop fast. For example, 1/8th setting was actually around 1/10th or -1/3 stop. So when I shoot Velvia 50 chromes, I may find that I'm underexposing. Many people already shoot chromes at 1/3 stop quicker so they don't blow the highlights. So it seems my lens shutter might be great for chromes. I'll bracket from box speed at least in the beginning, let's say +1/3 and -1/3, maybe +2/3 and -2/3. Then I can adjust for future shots.

    With BW I may have to slow it down, which is what people do anyway. I'll bracket at +1 and -1 stops from box speed to see what I get.

  10. #30
    Alan Klein's Avatar
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    Re: Copal 0 shutter accuracy

    Quote Originally Posted by Chauncey Walden View Post
    I suppose one more question would be just what to you plan to do with LF transparencies (other than look at it once and say "oh, neat") that wouldn't better be done with negative film?
    I scan my photos and I like transparencies better than negatives. I know exactly what I got exposure wise by looking at the film, especially if I bracketed. Plus I've found Velvia chromes easier to scan than Ektar negative color and color correct in post processing. In any case, whichever I use, I plan to use digital printing which I believe comes from a scan. I'm not going to do chemical printing. Also, once scanned, I can make slide shows for UHDTV, and use on the web, in FLickr, and even here in the forums.

    But I'm open to change.

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