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Thread: Bellows and lensing question

  1. #1

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    Bellows and lensing question

    Hello all. Im a bit new so please forgive me if i use a few terms incorrectly.
    I am in the planning phase of building a 8X10 wooden camera with a bellows. I own a brass petzval lens. Taking the recommendation from another post, i mounted the lens in a cardboard box, and using a sheet of paper to see focus i drew two lines. One when i was focusing on something very far off (infinity), and then when i was focusing on something close (2ft). For this lens, my lens board needs to be able to travel away from the film plane at a distance of 9 to 15 inches. It occurs to me that if i were to purchase a modern lens down the road, I would like to make sure that i can hit infinity focus with all or at least most lenses. I have not been able to find a chart that has that info. Or perhaps there is a general rule of thumb?
    Thanks

  2. #2

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    Re: Bellows and lensing question

    To keep it simple, you need the distance from film plane or gg to about lens iris to equal your focal length to focus to infinity...

    To shoot close (1:1, the frame size and the size of your shooting area) requires double your focal length extension...

    There are formulas to calculate different distances, but this would a nice range to work with if possible...

    Steve K

  3. #3

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    Re: Bellows and lensing question

    Thanks for the info. Now I think I can start cutting.

  4. #4
    Mark Sawyer's Avatar
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    Re: Bellows and lensing question

    To put it simpler, get a modern lens with the same focal length as your Petzval. It will focus in the same place. It's a focal length thing. Focal lengths just do that. You know, focus at a particular length. It's in their nature...

    If I were a focal length, that's what I'd do...
    "I love my Verito lens, but I always have to sharpen everything in Photoshop..."

  5. #5

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    Re: Bellows and lensing question

    On this very site, there is a pretty decent resource. Check this link, and note the film to flange distance (for infinity)

    https://www.largeformatphotography.info/lenseslist.html

  6. #6

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    Re: Bellows and lensing question

    I like it. Nice and simple

  7. #7
    Ron (Netherlands)'s Avatar
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    Re: Bellows and lensing question

    If you don't want to lose light when close focusing and thus preventing a lot of bellow stretch, one could make use of push-on close focus lenses.
    In the old days for that reason many used Carl Zeiss Proxar and Distar lenses.
    Btw these push-on lenses were not made to combine with the so-called convertible lenses like the Double Protars and other double anastigmats where each pair of lenses could be used separate to acquire a different focal length.
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