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Thread: Calibration vs. Consistency

  1. #1

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    Calibration vs. Consistency

    I was using my Pentax digital spot meter yesterday and got to thinking about the fact that I've never had it calibrated or even tuned up in over twenty five years and thus have no way of knowing if it is accurate. Let's say, for the sake of argument, that it is many stops off of some absolute standard and that what it reads as EV 12 is really EV 9. Since I use the same meter for all my exposures and have determined my own exposure indexes and development times for various films based on this meter's readings, what good would getting it calibrated do? It seems to me that as long as the meter is able to read relative values accurately--a six stop scene brightness range meters as a six stop scene brightness range--then all is good.

    So I was wondering: is calibration of photographic measuring devices important, or is it better to use consistently functioning equipment in the same manner every time?

    Jonathan

  2. #2

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    Re: Calibration vs. Consistency

    Consistency beats everything when it comes to getting the results you want. Once you are there why move?

    RR

  3. #3

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    Re: Calibration vs. Consistency

    In my opinion, a lot of this has to do with chasing a level of accuracy and control that is neither there nor entirely necessary (at least within the range of our typical use). Consider print control - no matter how much you try to be accurate and control things, there will always be variation - some random and some systematic. Timers come with some range of random error, your ability to have the print in the developer for precisely 60/90/120/whatever seconds comes with some random error. Developer composition changes systematically through a printing session - as you put more paper through the developer, bromide accumulates in the developer which should have the same effect as adding a restrainer. Over a long enough printing session, you might be puzzled by why your printing paper seems to be growing slower, especially if you print the same negative at the start and the end of a really long printing session. And of course you change - you are probably more tired at the end of a printing session than at the beginning but your judgment may be better because it is in the zone and you are in a state of flow.

    Things drift - you can either compensate your process or get things routinely checked or use some combination of both. Some things are more sensitive/susceptible to vagaries than others. It is probably not a bad idea to have light meters checked occasionally because they sometimes take falls or bumps and occasional maintenance is just some insurance against catastrophic failure at some uncertain future point (or maybe I am more clumsy than most). And if you really want to get obsessive about it, you can calibrate your meter against some standard before and after servicing to factor in the necessary adjustment to your process. Although given vagaries in our metering skills and visualization, I am not sure this really achieves anything. The final limiting factor is human - even if we had perfect unchanging materials, we change in subtle and unsubtle ways, both in the short term and the long term. Once we reach an acceptable level of accuracy, chasing accuracy beyond that is mostly pointless - there are other things our energy could be spent on in an effort to improve our photography.

    Cheers, DJ

  4. #4

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    Re: Calibration vs. Consistency

    Quote Originally Posted by Regular Rod View Post
    Consistency beats everything when it comes to getting the results you want. Once you are there why move?

    RR
    Amen, brother!

  5. #5

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    Re: Calibration vs. Consistency

    Jonathan based on your great images both your calibration and consistency are correct - for you. Your calibration is your eye and that seems very accurate.

  6. #6

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    Re: Calibration vs. Consistency

    Quote Originally Posted by Shen45 View Post
    Jonathan based on your great images both your calibration and consistency are correct - for you. Your calibration is your eye and that seems very accurate.
    Thanks. My approach is certainly based more on feel than objective standards. Almost all of my shutters are old and slow and out of whack, so I have learned to deal with a certain amount of "slop" in my exposures which I attempt to compensate for during processing. If we're able to get the results we want I suppose the method doesn't matter too much. I'm not looking to change my way of working, but I was curious how other people use and maintain their equipment.

    J.

  7. #7
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    Re: Calibration vs. Consistency

    Quote Originally Posted by jcoldslabs View Post
    Since I use the same meter for all my exposures and have determined my own exposure indexes
    Seems like you have calibrated it.

  8. #8

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    Re: Calibration vs. Consistency

    I've seen your work. Your meter ain't broke..... dont fix it.

  9. #9

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    Re: Calibration vs. Consistency

    Quote Originally Posted by bruce osgood View Post
    i've seen your work. Your meter ain't broke..... Dont fix it.


    rr

  10. #10

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    Re: Calibration vs. Consistency

    The Zone System is valuable largely for just this reason. It introduced a consistent, repeatable process where before there was usually a great deal of haphazardness. All the rest of the Zone System methodology is just fine tuning.

    --Darin

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