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Is this normal image quality for a Rebel t3i?

Discussion in 'Canon' started by Vraeth, Dec 6, 2013.

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  1. Vraeth

    Vraeth New Member

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    Hi, I recently purchased a Rebel t3i-- I am new to DSLRs and photography in general. The main use for this camera is to photograph my traditional media visual art and to take reference photos for drawings. The reference photos do not have to be spectacular, but when I want to photograph a drawing, it would be in place of scanning it, so I am hoping for similar quality.

    The attached image is a small portion of a photo which represents an issue I am having with the images. It seems like there is some weird red-green shift (maybe due to misalignment? but I don't know how a digital sensor could be misaligned). It is mainly noticeable around the edges of the text. The graininess is also unfortunate, but I expect that this is somewhat unavoidable unless you pay out for really high quality equipment.

    Note that I am shooting in RAW at full (18 MP) resolution, and this portion is zoomed in at 100% of the original image. Also, I was not shooting from a tripod per se, but the camera was sitting on a desk. This is using a telephoto lens, but the kit (18-55mm) lens produces similar results, though this is one of the more pronounced examples. Is this shifting normal? the pixelation? Any way to reduce/eliminate?

    Thanks very much for the help!
    [​IMG]
     
  2. Andy Stanton

    Andy Stanton Super Moderator Super Moderator

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    What you're observing is a form of lens distortion called "chromatic aberration" or "purple fringing". You sometimes see it when you have a light/dark contrast. Better lenses have less chromatic aberration.
     
  3. KCook

    KCook Well-Known Member

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    Andy is right. Sometimes (not always) chromatic aberration ("CA") can be reduced by using a smaller aperture. In any event the RAW editor supplied with Canon cameras includes a tool for reducing CA in post processing. This link is to the video tutorials for this editor (Digital Photo Professional). Covers the entire editor, the section on the CA tool is #23 -

    Canon DLC: Gallery: Digital Photo Professional Tutorial Videos (v3.8 - 3.11)

    Kelly Cook
     
  4. Vraeth

    Vraeth New Member

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    Thank you for the replies! very helpful :)
     
  5. canonfanatic14

    canonfanatic14 Member

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    I agree. Pretty normal.
     
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