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Thread: 90 inch bellows - what is exposure?

  1. #21

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    Re: 90 inch bellows - what is exposure?

    Quote Originally Posted by Tim Meisburger View Post
    ...I hope the OP reports the final result!...
    I hope so too, Tim. We've not heard from him since he first posted his questions. Perhaps he's out actually shooting.

    FWIW, years ago, I set up my Sinar Norma at home to check out where on the lens to measure for the bellows extension; I did this for each of my lenses (3 Symmars and 3 Super Angulons) focused on infinity. Found that all the Symmars could be measured to the aperture control ring and all the SA's could be measured to the front of the lensboard. Then I made up a small chart of exposure factors calculated at incremental bellows extensions out to the bellows limit. It includes all six lenses. I keep that little chart in my field notebook (that is always with me); it saves having to do the calcs in the field, avoiding possible errors. I, too, use a very small metal re-coiling tape measure. So I only need to measure the extension, look up the factor, then shoot. It's a very fast system. We all make choices for our workflow, that's mine.

    BTW, I'm curious whether I'm the only one who's noticed that OP stated his lens has no shutter. I tried to help him a bit in dealing with that.
    Last edited by Jerry Bodine; 15-Aug-2017 at 11:25.

  2. #22

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    Re: 90 inch bellows - what is exposure?

    From about 22 to 90 in f-stop inches is 4 stops.

  3. #23
    Tim Meisburger's Avatar
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    Re: 90 inch bellows - what is exposure?

    This tool (Quick Disk) also works well. I printed one and then laminated it with clear packing tape, and it lives in my camera bag. http://www.salzgeber.at/disc/index.html

  4. #24

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    Re: 90 inch bellows - what is exposure?

    This is a helpful thread, but I would love to see a photo of a 90 inch bellows extension. It must be quite breath-taking.

  5. #25

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    Re: 90 inch bellows - what is exposure?

    Quote Originally Posted by Tim Meisburger View Post
    This tool (Quick Disk) also works well. I printed one and then laminated it with clear packing tape, and it lives in my camera bag. http://www.salzgeber.at/disc/index.html
    Tim, that certainly is a useful convenient tool. I carry it as well, and it handles the bulk of any close-ups I do. But it is limited to only a two-stop correction.

  6. #26

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    Re: 90 inch bellows - what is exposure?

    Quote Originally Posted by Jim Michael View Post
    From about 22 to 90 in f-stop inches is 4 stops.
    Yes it takes about five seconds to figure that out. I can't believe we're still talking about this

  7. #27

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    Re: 90 inch bellows - what is exposure?

    Thanks to all for the insights and suggestions. I shall try Rich's formula first.

    I will be happy to share the results here.....but that is a quandry. It will be a tiny image that can only really be appreciated in person.

    Francis Fullam
    Chicago, IL

  8. #28

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    Re: 90 inch bellows - what is exposure?

    What Tim said in the second post. Measure the hole. Measure the length. Divide. Easy-peasy. 2" hole, 90" extension f45. 1 inch hole 90 inch extension f90. 1 1/2" hole, class? right, f64 No need to make it any harder.

  9. #29

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    Re: 90 inch bellows - what is exposure?

    Quote Originally Posted by Luis-F-S View Post
    Yes it takes about five seconds to figure that out. I can't believe we're still talking about this
    What Jim and Luis state. This is without a doubt, the easiest method. It's simply 4 stops going 22(24) inches to 32, 32 to 45, 45 to 64, 64 to 90.

  10. #30

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    Re: 90 inch bellows - what is exposure?

    Hullo FrancisF..
    I strongly doubt that in a "shaded area" you have an answer from lightmeter of 1/1000 s. at f. 11. Just remember the f. 16 rule in full sun with shutter speed reciprocal of film ASA.. Therefore in full sun you should have this reading: f. 16 @ 1/125 s. Given you taking the picture during the midday hours..
    I would check first how correct the reading of lightmeter is (battery ?)

    If the subject is in an "open shadow" (i.e shaded by tall building w/out strong reflection from nearby water or glass building) I would open iris up to f. 4 or use 1/8 s. shutter speed if appropriate.. F. 4 @ 125 s. or f. 16 @ 1/8 s. are the starting points to THEN make all calculations advised above ..

    Best

    Mauro

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