measuring vignetting

Discussion in 'Photography' started by camera_dude, Feb 27, 2008.

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  1. camera_dude

    camera_dude Member

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    Hello,

    I am trying to understand how to measure vignetting. I did a google search and turned up the following

    http://www.cameralabs.com/reviews/CanonA640/page4g.shtml
    http://www.dpreview.com/reviews/CanonEOS300D/page17.asp

    I would assume that the fall of mentioned in the canon eos300 link refers to the amount of loss of illumination
    whereas the canon a 640 link refers to the % of light transmitted at the edges, hence for the sony cybershot DSC N2, the mean corner fall-off which is 86.9% in equivalent terms is a 13.1% fall-off.

    what is the better measure the average fall off or the mean corner fall off? would the measurement be carried out at normal zoom (no zoom)?
     
    Last edited: Feb 27, 2008
  2. David Rasnake

    David Rasnake News/Review Writer News/Review Writer

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    As I understand it, the methodologies get at the same information; I don't think there's a substantive difference in the measurement approaches, from what I can gather.

    Vignetting is (usually) only an issue at wide angle, and at wide apertures. Hence, most testing occurs at these settings. As the dpreview article notes, vignetting resolves itself pretty quickly on the Canon kit lens once you zoom beyond wide angle and/or stop the aperture down.

    dr
     
  3. camera_dude

    camera_dude Member

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    thanks for the reply David,

    in the drpreview article the falloff ranges between 7 and 24%, whereas in the cameralabs article the fall off ranges between 67 and 87%.

    i guess the dpreview falloff is the amount of light not transmitted and the cameralabs value is the amount of light transmitted. i looked at the imatest report and it seems that they give the fall off in terms of the cameralabs article. is that teh standard?
     
  4. David Rasnake

    David Rasnake News/Review Writer News/Review Writer

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    Seems like it.

    dr
     
  5. camera_dude

    camera_dude Member

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    thanks for the reply.

    makes sense now.
     
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