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Thread: lens testing info?

  1. #1
    Steve
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    lens testing info?

    Hi guys, I posted this in the canon forum but thought I would post it here also seems like a little more traffic here. What is the proper method for checking accuracy of lenses. I've heard to use a ruler at an angle. What distance is appropriate? Any info would be helpful. I am checking for front or back focus issues. Thanks Steve

  2. #2
    Senior Subscriber Member Steen's Avatar
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    Re: lens testing info?

    I use Tim Jacksons Focus Test Chart. Full explanation on how to use it can be found at this website:
    http://focustestchart.com/chart.html

    And here is the url address to the PDF version of the website.
    You need to print page 18 of the PDF document.
    http://focustestchart.com/focus21.pdf

    / Steen

  3. #3
    Steve
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    Re: lens testing info?

    I should probably posted this in only one forum. Thanks for the help I will check it out. Steve

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    Sr. Administrator Jack's Avatar
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    Re: lens testing info?

    Hi Steve:

    I use to use fancy targets and rulers with tape on them, but now I simply shoot at lines in the sidewalk, focusing where two intersect at the distance I normally use the lens at, usually around 40x the lens focal length. With this method, it's really easy to see where your exact focus point was relative to where it should be... The 40x focal thing moves that point toward the usually more critical closer focusing distances where DoF will not always rescue slight mis-focuses.

    Cheers,
    Jack
    home: www.getdpi.com

    "Perfection is not attainable. But if we chase perfection, we can catch excellence."

  5. #5
    Steve
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    Re: lens testing info?

    thanks Jack, I was wondering shooting some of the ruler tests at such a close distance how you could measure how far out you are at say 10 feet or so.
    40x sounds like good advice. I'll give it a go.

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