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  1. #11

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    Buy that DoF calculator.

    Good luck!

  2. #12

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    Thanks Rod,easy sounds good,I can under stand where a telephoto lens would cause some problems with its shorter than rated focal length.Gotta get me one of those calculators.

    Mike

  3. #13
    ic-racer's Avatar
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    Works for me.

    If I am looking for a more exact measure, then, in order of preference, I'd use a TTL meter, followed by an image height scale. The probelm I have with measuring exact bellows extension is uncertainty as to the location of the lens nodal point and exact focal length of the lens.

  4. #14
    RalphLambrecht's Avatar
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    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  5. #15
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    Ralph when I print this calculator how long should the scale ruler be and what are the dimensions of the target? I want to verify that my printer did not change the scale.

    Is this calculator in "Way Beyond MonoChrome"? I got a copy last week and have only skimmed it so far.
    "Generalizations are made because they are generally true"
    Flicker http://www.flickr.com/photos/stradibarrius
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    Barry
    Monroe, GA

  6. #16
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    Quote Originally Posted by stradibarrius View Post
    Ralph when I print this calculator how long should the scale ruler be and what are the dimensions of the target? I want to verify that my printer did not change the scale.

    Is this calculator in "Way Beyond MonoChrome"? I got a copy last week and have only skimmed it so far.
    Print it full scale. Whatever inaccuracy your printer might have will be insignificant. Page 192 and 520.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  7. #17
    Rick A's Avatar
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    Ralph, I made two of your calculators and laminated them. One lives in my LF gear bag, my daughter grabbed the other. This is the handiest no brainer accessories I own. Thank you.
    Rick A
    Argentum aevum
    BTW: the big kid in my avatar is my hero, my son, who proudly serves us in the Navy. "SALUTE"

  8. #18

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    Fred Picker had a method of bellows factor that was fast and simple. If we have and 8 inch lens and we increase the bellows to 10 inches then I just do a factor of 1 stop extra...you can fudge it a little but it works for me..just bring a measuring tape along in the field or wherever you go. no charts and no calculations...KISS PEOPLE!
    have a nice day!
    Peter
    website down for maintenance!

  9. #19
    2F/2F's Avatar
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    Quote Originally Posted by Peter Schrager View Post
    Fred Picker had a method of bellows factor that was fast and simple. If we have and 8 inch lens and we increase the bellows to 10 inches then I just do a factor of 1 stop extra...you can fudge it a little but it works for me..just bring a measuring tape along in the field or wherever you go. no charts and no calculations...KISS PEOPLE!
    have a nice day!
    Peter
    10/8 = 1.25.
    1.25x1.25 = 1.56

    You and Mr. Picker favor 2/3 stop of overexposure as a matter of course? Your picture will live with negative film, yes. But it is not ideal. And it will make shots on transparency film (or digital, for that matter) end up obviously technically flawed.

    And how do you generalize that method for when people do not have an 8 inch lens at 10 inches of extension? You'd need to use percentages instead of just a single example. So, "extend bellows to 125 percent of focal length, and you add a stop." Except that is not correct. Not even really close.

    Sounds too complicated to me, besides that fact that it only works with negatives, and sloppily at that...

    Just divide the little number into the big number, then square the result. Simple.

    If you meant to write "12" where you wrote "10," you are correct. If you extend to 150 percent of the focal length, you add a stop. But the typo is just one example of what can happen in your brain when working on the shot. Easier to stick to the standard formula IMO.
    Last edited by 2F/2F; 02-21-2011 at 07:25 PM. Click to view previous post history.
    2F/2F

    "Truth and love are my law and worship. Form and conscience are my manifestation and guide. Nature and peace are my shelter and companions. Order is my attitude. Beauty and perfection are my attack."

    - Rob Tyner (1944 - 1991)

  10. #20

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    If I remember correctly (from Steve Simmons book "Using the View Camera") the rule if shooting within 10 times the focal length "Add 1/2 stop for each 25% increase in bellows extension". It works just fine.

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