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Thread: Copal 0 shutter speed accuracy

  1. #1

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    Copal 0 shutter speed accuracy

    Hi,

    I recently purchased Schneider Symmar APO 150mm Copal 0. I conducted an improvised test with the shutter set at 1s, with the iPhone memo app. And got results varying from 1.2s to 1.28s.

    Click image for larger version. 

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    I'm sure using iPhone app is not optimal but at 1s it seems it would be good enough to tell if something is off. Should I return this lens?

    Thanks

  2. #2
    Les
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    Re: Copal 0 shutter speed accuracy

    Is the lens in good condition ? Why not have the shutter cleaned/lubed/adjusted ? Usually the faster speeds are not as accurate.
    Les

    On occasion I noticed there is real life outside the GG/viewfinder.

  3. #3

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    Re: Copal 0 shutter speed accuracy

    The lens is in a pretty good condition, I would say it looks great. I live in South East Europe and I have a very limited pool of people who could do CLA.

  4. #4

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    Re: Copal 0 shutter speed accuracy

    Before you get concerned, I'd suggest that you redo the test on a computer with a better application. Just about any microphone that you can plug into the computer will be adequate. What you need is an app with a good waveform display. If you're on a Mac, GarageBand, which is free and may already be on your computer, will handle this just fine. After that, my first choice would be iZotope's RX. It has a ten day free trial, but I don't recall what limits there are. You could also use Reaper, which is also excellent and which you can use without any limitations indefinitely. I would use any of the foregoing in preference to Audacity.

  5. #5

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    Re: Copal 0 shutter speed accuracy

    There is an app. "Shutter-Speed" that makes a fairly good job, att least upp to 1/125 secs.
    The free version uses the microphone and audio.

    Myself I wouldn't worry about 1.2 seconds compare with a second. That's pretty accurate. It's not even a third of a stop.
    And being accurate at longer times is not an indication that faster times are OK I'm afraid.

    And times from 1/250 and faster are almost never accurate, even when CLAd.

    It the lens is fine download the app and check to see if it's ok up to 1/125.
    Most of us would never use that fast times anyway.

  6. #6

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    Re: Copal 0 shutter speed accuracy

    And it really doesn't matter if speeds are off a bit as long as they are consistent.
    I measure my shutters and have a spreadsheet to prepare labels with compensations that I stick to the lens board

    Here is one for a Copal #3
    Attachment 218407

  7. #7

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    Re: Copal 0 shutter speed accuracy

    Quote Originally Posted by lassethomas View Post
    There is an app. "Shutter-Speed" that makes a fairly good job, att least upp to 1/125 secs.
    The free version uses the microphone and audio.
    The free version of that app won't be any more accurate than iPhone Voice Memos.

    There's an old series of photo.net posts from Tom Johnstone that establishes that a standard audio recording waveform will show shutter speeds accurately up to 1/30 or maybe 1/60 second. I say establishes because Johnstone did his recordings right after having his lens CLA'd by S.K. Grimes, and the recording waveforms were dead on with Grimes's report. At the time, a lot of people held the view that no audio recording, by itself, would provide accurate data on shutter speed. Indeed, that view underlies the statement by the vendor of the "Shutter Speed" app that one should purchase an optical accessory if one wants greater accuracy.

    I know from synchronising iPhone audio with video that there are issues with iPhone audio. More importantly, you need an application that will give you an accurate, detailed waveform display. You will get that from a Digital Audio Workstation like GarageBand (free to Mac users) or Reaper (free if you don't want to pay). You will also get it from iZotope RX, which is professional sound editing software that for this purpose would be easy to use. Indeed, I'm about to use RX8 to test two of my own lenses. I just don't recall what the limitations are on the RX trial. Audacity will work too, I just find it not very intuitive and a bit clunky
    Last edited by r.e.; 6-Aug-2021 at 20:19.

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

    Mechanical shutters have plus or minus 20 or 30% specs

  9. #9

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    Re: Copal 0 shutter speed accuracy

    Quote Originally Posted by r.e. View Post
    The free version of that app won't be any more accurate than iPhone Voice Memos.

    There's an old series of photo.net posts from Tom Johnstone that establishes that a standard audio recording will show shutter speeds accurately up to 1/30 or maybe 1/60 second. I say establishes because Johnstone did his recordings right after having his lens CLA'd by S.K. Grimes, and the recordings were dead on with Grimes's report. At the time, a lot of people held the view that no audio recording, by itself, would provide accurate data on shutter speed.

    I know from synchronising iPhone audio with video that there are issues with iPhone audio. More importantly, you need an application that will give you an accurate, detailed waveform display. You will get that from a Digital Audio Workstation like GarageBand (free to Mac users) or Reaper (free if you don't want to pay). You will also get it from iZotope RX, which is professional sound editing software that for this purpose would be easy to use. I just don't recall what the limitations are on the RX trial.
    Well yes, accuracy will be the same as Voice Memo, but there is a build in measuring tool and direct display so it's much more convenient and faster to use.

    And if you want to go for a desktop application there is also Audicity as an open source alternative

  10. #10

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    Re: Copal 0 shutter speed accuracy

    Quote Originally Posted by lassethomas View Post
    Well yes, accuracy will be the same as Voice Memo, but there is a build in measuring tool and direct display so it's much more convenient and faster to use.

    And if you want to go for a desktop application there is also Audicity as an open source alternative
    I was editing to include a reference to Audacity while you were posting. Audacity will work, but it would be my last choice.

    As I said, there are issues with iPhone audio. I don't trust it for time measurement. I also think that it's highly unlikely that the waveform display from an iPhone app will come close to the display that one will get from a DAW or iZotope RX. I have a number of recording apps on my phone, including one from DPA Microphones, whose miniature mikes/lavalieres I use, and I would not use any of them for this purpose.

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