Using calculators for photographic ends

Discussion in 'Miscellaneous Equipment' started by Tom Kershaw, May 20, 2009.

  1. Tom Kershaw

    Tom Kershaw Subscriber

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    Rereading the thread I started on reciprocity of available sheet films, I started thinking about using a calculator for other purposes related to photography. For instance, after calculating reciprocity failure, one could then run a count-down timer to time the exposure. Another use might be to calculate f-stop timing intervals from a spreadsheet or matrix of pre-existing numbers. Say enter 6 seconds at the minimum time and 12 as the end time, with 1/4 stop intervals, produces a list; 1.9, 1.6, 1.4, 1.1, 6. etc.

    Would those with more experience in using programmable calculators care to comment on these thoughts?

    Tom.
     
  2. BradS

    BradS Subscriber

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    I regularly use an ordinary pocket calculator (HP-32s) to compute bellows factors. I guess I could write a short program to automate it somewhat...just never bothered.
     
  3. Q.G.

    Q.G. Inactive

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    I did a lot of high magnification work, and had a calculator always at the ready.
    Made a small computer program that did all the different calculations i need in one go.

    A version of that program, tailored to Zeiss/Hasselblad lenses, is online.

    Still want to port it to run on PDAs, but haven't gotten round to it.


    Reciprocity failure is to 'unruly' to capture in a calculator.
     
  4. Konical

    Konical Subscriber

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    Good Morning,

    I use a calculator to determine changes in print-exposure times when I change sizes. Much of the time, experience gives me what I need, but the calculator provides reassurance.

    Konical
     
  5. Frank Szabo

    Frank Szabo Member

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    Can't be any worse than scratch-writing a Fortran program for Simpson's Rule and that's not difficult (assuming a suitable quantity of adult beverages) ...

    Couldn't reciprocity failure be expressed as one would a limit? (think beginnings of the calculus - not the stuff on one's teeth).
     
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  6. Tom Kershaw

    Tom Kershaw Subscriber

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  7. archphoto

    archphoto Member

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    Reciprocity is for each film diferent.
    I gues you are better of with a little cardboard with those data for the films you use most.

    Peter
     
  8. Tom Kershaw

    Tom Kershaw Subscriber

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    Peter,

    In the thread I linked to Patrick Gainer discusses a formula for working out the needed increase in exposure to account for reciprocity failure, using a correction factor derived for each film type.

    Tom.
     
  9. Q.G.

    Q.G. Inactive

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    The important bit in this reciprocity failure thing is expressed by the word failure.
    If there was an easy rule, an unequivocal relation, a simple formula, Bunsen and Roscoe would have found it ages ago.

    You can explore the behaviour of films, and compile tables.

    But - and this is important - you cannot (!) calculate reciprocity failure.
     
  10. sage

    sage Member

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    Ive written a few small ones as needed for my cell phone, as its usually always there and with me, and less to carry around to not need the calculator.