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Thread: Precision and Accuracy in LF Photography: How much is enough?

  1. #1
    Drew Bedo's Avatar
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    Precision and Accuracy in LF Photography: How much is enough?

    There have been a couple of interesting threads lately on gear and technique that devolve into discussions of accuracy and precision.

    One had to do with the potential for focus shift when stopping down. Another revolved around the quality and precision of spirit levels used in LF photography.

    some responses on these threads involved discussions of precision in alignment and leveling that only a machinist would worry about. Which brings up a question in my mind: How much precision and accuracy is enough? Alignment and plumbnb-ness are just two parameters of what we do though.

    So just how accurate are shutter speeds? A speed of 1/500th should equal 2 mili secs. Setting 1/250th should be 4 mili sec and 1/125th ought to be 8 mili sec if I have counted on my fingers correctly. A half sec should be 500 mili sec.

    So how close is close enough? Is plus-or-minus 10% acceptable? Do we even get +/_ 10%? What should we expect as to accuracy and reputability (precision) from a new-ish Copal shutter? How many sequential tripps of a shutter come how close to the nominally set speed? What about older designs; Compur, Alphax, etc. ?

    What about Lightmeters?

    What about aperture settings or focal length? How close are the markings to acrtual and how close do we need them to be?
    Drew Bedo
    www.quietlightphoto.com
    http://www.artsyhome.com/author/drew-bedo




    There are only three types of mounting flanges; too big, too small and wrong thread!

  2. #2

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    Re: Precision and Accuracy in LF Photography: How much is enough?

    It depends on whatever aspect/part of the process you’re talking about, along with one’s aesthetic preferences etc. Some parts of the process inherently have, and tolerate a lot of slop. Other parts are potentially more problematic. But it is all quite subjective. There is also the enjoyment factor, since nearly all LF photographers are hobbyists. What is an irritant to one person is a non issue to another.

    I guess you can sum it all up with the often used “YMMV”.

    When it comes to specifics, I can only speak for myself, and I really can’t relate to how most other people do this stuff.

  3. #3

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    Re: Precision and Accuracy in LF Photography: How much is enough?

    Good questions for having discussions at the picolux and femtolux protection society. But just like you, I feel that some are only of concern for machinists and lab equipment.

    For me the greatest question is alignment between film plane and ground glass. Is my ground glass where my film will be? Shutters, I think we can be happy if we get +/- 10-20%. Just the way between the lens shutters work makes the point where you measure that a shutter is open or closed is already debatable.

    And then you have not touched iso, spectral sensitivity and whatever joins the club when you start developing.

    Also, let us not forget that a lot of what we play with are not linear functions but logs and powers. So what is the influence of 10% on a parameter that is basically changing by power of 2?
    Expert in non-working solutions.

  4. #4
    Vaughn's Avatar
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    Re: Precision and Accuracy in LF Photography: How much is enough?

    Depends on one's personality. Some folks psychologically need precision...they need to know. And some people don't. And most people are in between.
    "Landscapes exist in the material world yet soar in the realms of the spirit..." Tsung Ping, 5th Century China

  5. #5

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    Re: Precision and Accuracy in LF Photography: How much is enough?

    Since the inception of photography, “approximately “ has been good enough. It’s time to re-validate that, even when lots of “approximates” in the same direction cumulate. Of course there are limits and that’s when the negative absolutely can’t be used. Perfection is the enemy of good enough.

  6. #6
    Kirk Gittings's Avatar
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    Re: Precision and Accuracy in LF Photography: How much is enough?

    I like to concentrate on the image and not the technology when I shoot. I want the technology to be tested and dependable whether it is ISO, Zone placement, levels or whatever so I don't have to worry about it in the field.
    Thanks,
    Kirk

    at age 70:
    "The woods are lovely, dark and deep,
    But I have promises to keep,
    And miles to go before I sleep,
    And miles to go before I sleep"

  7. #7
    Drew Bedo's Avatar
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    Re: Precision and Accuracy in LF Photography: How much is enough?

    I agree, in general, with all of the responses so far. I was a bit surprises when some of the discussions involving a machinist's and other responses on precise, sensitive (expensive) spirit levels and calibration geared movements with laser pointers etc.

    I mean, if its good for you . . .go for it. On the other hand, I am working with two wooden field cameras, one of them much older than me, and neither of which have geared anything. . . .and I am OK with what they can do.

    And yet I welcome any other discussion of accuracy and precision in LF photography.
    Drew Bedo
    www.quietlightphoto.com
    http://www.artsyhome.com/author/drew-bedo




    There are only three types of mounting flanges; too big, too small and wrong thread!

  8. #8

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    Re: Precision and Accuracy in LF Photography: How much is enough?

    What I've come to find so interesting about analog photography is how it straddles "intuitive" and "scientific." You can take the Kodak scientific approach: expose exactly the 'correct' time based on exacting measurements of light, aperture, etc... develop at exacting 'correct' times and temperatures, etc... and you will consistently get images with the 'correct' density as determined by Kodak's labs. OR... you can wing it, guesstimate and eyeball things, and after enough experiences, you'll probably consistently get good images too. Which is 'right'? Both? Neither?
    Personally, when I'm starting off into a new unknown, I will approach it scientifically and do things the 'correct' way until I get a sense for what is going on. After that, I prefer to go full intuitive mode and just have fun creating. I take this approach to most things in life.

  9. #9

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    Re: Precision and Accuracy in LF Photography: How much is enough?

    “ Kodak scientific approach”

    Even that acknowledges variability in many aspects of photography. What it does is standardize those aspects that their products can affect. It significantly increases the probability of success by reducing at least a few sources of variance.

    I completely concur that following that kind of wisdom is worthwhile!

  10. #10
    Drew Wiley
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    Re: Precision and Accuracy in LF Photography: How much is enough?

    Just depends on what you're trying to achieve. A scientific or technical industrial photographer using large format equipment might have reason to be quite nitpicky. Each minor error tends to adds up to a cumulative loss. Somebody else, perhaps making contact prints and deliberately using a soft focus lens might be more willing to wing it. I suspect that most of us are somewhere in the middle, but on a varying scale in that respect. Esthetically, one ideally wants their tools to match their vision. Some people do chainsaw sculptures using old logs, others need very sharp chisels indeed. Some shoot large format for sake of its potential for high detail rendition in serious enlargements, some do not. After one has been on the road awhile, so to speak, they begin to understand their own specific needs and what it takes to efficiently get from Point A to Point B.

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