Bellows Exposure calculation

Discussion in 'Large Format Cameras and Accessories' started by smithdoor, Nov 5, 2013.

  1. smithdoor

    smithdoor Member

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    If you need Bellows Exposure calculation down load with filter calculation
    Try this wheel for calculations

    Dave​
     

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    Last edited by a moderator: Nov 5, 2013
  2. smithdoor

    smithdoor Member

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    Upload on aperture shutter speed table
     

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  3. RalphLambrecht

    RalphLambrecht Subscriber

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    Well done, but Iprefer the method where a target disk is placed into the scene and it's size is measured on the ground glass .a ruler measures the disk diameter, which has a direct link to the exposure compensation required.
    good luck. ask for a free pdf of this method by sending a request to rlambrec@ymail.com
     
  4. smithdoor

    smithdoor Member

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    Thank you
    I have look at the disk look good too.

    Dave


     
  5. Tom1956

    Tom1956 Inactive

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    A lot of that Lambrecht stuff I've seen is pretty easy, clear, and logical. That PDF download makes me want to keep my Kodak Master Photoguide more handy. Good effort though.
     
  6. RalphLambrecht

    RalphLambrecht Subscriber

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    I'm honored; thanks for the nice words, but let's not forget, I too have learned a lot from APUG.
     
  7. Rick Rosen

    Rick Rosen Member

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    A simple way to calculate exposure compensation is to use a ruler. I keep a small tape measure with me for this purpose.

    Follow along:

    1. In your mind convert your len's focal length to inches.

    Examples:

    90mm = 3.5"
    150mm = 6"
    210mm = 8.25"
    300mm = 12"

    2. Now focus any one of your lenses at infinity It will be it's mm length from the film plane. I use the film plane and the center of the front standard to measure from.

    3. In your mind convert the mm focal length to inches.

    Round it off to the closest f/number.
    In your mind call the resulting number an f/stop.
    For example my 210mm lens is 8.25" which is my f/8 lens.
    My 90mm lens is 3.5" which is my f/4 lens.
    150mm lens is 5.9" which is my f/5.6 lens.
    300mm lens is my f/11 lens (close enough to 12")

    4. When you are focused for your photograph use the tape measure to measure the distance from the film plane to the front standard reference point.

    Examples:

    Lets say for example that you are using a 210mm lens and it is focused at 11 inches. 210mm = "f/8" and my "f/8 lens" at 11' is f/11. f/8 to f/11 = One stop bellows compensation.

    Fast and accurate. Try it.
     
  8. RalphLambrecht

    RalphLambrecht Subscriber

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    Is this a futile attempt to convince the world to hang on to inches?:tongue:
     
  9. ROL

    ROL Member

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    Futile perhaps. But I've always found it kind of necessary to hang on to your inches.
     
  10. Jim Noel

    Jim Noel Member

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    I'm with Ralph. All these other methods are too time consuming. I use a square chip placed in the scene and its image measured on the ground glass. Quick, simple and easy to make and carry around.
     
  11. StoneNYC

    StoneNYC Subscriber

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    Can you show a picture?
     
  12. BrianShaw

    BrianShaw Member

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  13. BrianShaw

    BrianShaw Member

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    See the very bottom of the page. Click link. What Ralph and some of us use is a variant of this in which the target is square instead of round. At one time Calumet sold such a tool but there are several available on the internet.
     
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  15. BrianShaw

    BrianShaw Member

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  16. BrianShaw

    BrianShaw Member

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  17. rbrigham

    rbrigham Member

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    Another device to me sure bellows compensation

    Please see the attached for another tool to workout bellows extension
    this one was for 35mm but the idea will work with any format

    robin
     

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  18. BrianShaw

    BrianShaw Member

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    p.s. I normally charge between $150 and $200 per hour to do research. :wink:
     
  19. StoneNYC

    StoneNYC Subscriber

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    I was talking to Jim about his GG cutout thing... LOL

    But thanks, all those pages are too complicated for me, I looked at it and was like, "yea no.." Lol

    I already use the reciprocity timer app for all my work, but just in case I'm ever in a situation where my phone doesn't work (like a week in the canyon) I would like to have some kind of card to help out :smile:

    In fact, I don't even know if I'm measuring right, I assume it's from the film plane, to the center of the lens (lens board area) but it could be from the rear element? I don't even know haha, I'm not very precise with it, but it hasn't seemed to affect me too much.
     
  20. BrianShaw

    BrianShaw Member

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    Maybe you need to stop typing and read the material. It's really very basic and well explained. Yes, the measurement is between the film and lens planes, but as you say being really precise or accurate isn't really necessary. Jim's "cut-out thing" is in more than one of those links. They may be round instead of square, but same thing.
     
  21. StoneNYC

    StoneNYC Subscriber

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    I was assuming it was some kind of PDF you could print and cut out that's what I was looking for so I saw the pages with math on it I just didn't bother :-0
     
  22. Alan Klein

    Alan Klein Member

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    I don't normally do closeup work. But my Mamiya RB67 medium format is really very capable of that and has bellows adjustment markings on it to make adjustments. Are those accurate or do you have to do more?
     
  23. BrianShaw

    BrianShaw Member

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    You kids are going to drive me crazy. Post 15. Click and print, then cut out with scizzors. Ignore all of the others since they have words and numbers. :D
     
  24. StoneNYC

    StoneNYC Subscriber

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    Hahhaa!!! It's true, we are lazy, we grew up with calculators instead of slide rules, never learned to count with beads like you old folks :wink:

    :munch:
     
  25. StoneNYC

    StoneNYC Subscriber

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    I have the same Mamiya RZ67 and the chart works fine, it's a wonder to me they didn't incorporate the same sort of chart on all modern LF cameras, it seems kind of like a no brained to me, but no one's done it yet, I mean the least they could have done was added ruler markings on the field camera bodies so you didn't have to carry one in the field, sometimes I wonder about these engineers... Lol
     
  26. BrianShaw

    BrianShaw Member

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    Probably better to ask the marketing guys than the engineers. Engineers love numbers, and scales, and marking, and all sorts of technical stuff. Marketing guys are better at figuring out what the majority of users want and need and will pay for. But if you wonder about engineers, start a thread and ask away. Me and my kind will be glad to give you an education. Just have a slide rule ready so you can understand the lesson and do your homework. [as you say: :munch:]