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Thread: Why all these aberrations?

  1. #1
    New Member
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    Feb 2011
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    Bryan, Texas
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    Cody

    Why all these aberrations?

    I want wandering around Texas A&M's campus on Wednesday and snapped this candid portrait of a girl reading in a tree.

    I was using my Canon T1i with a FD 50 mm f/1.4 with a necessary FD/EOS adapter (uses a 1.4X teleconverter to maintain infinity focus)

    Shot using the aperture priority setting, a manually set f/ ~8, ISO - 100, and an exposure time of 1/250.

    I like the overall effect I achieved in this photo. I know the background is overexposed, and something weird is happening to my subject. However I don't understand at all how my lens/camera combination worked to produce this aberration.

    Are my bleeding highlights a product of poor manual focus? Are they because of the poor quality of the 1.4 teleconverter glass? Is it some product of my in-camera image processing? Is it just because my highlights are overexposed and clipping?

    I would love to reproduce this effect, but sans the abberations in my subject.

    Thanks in advance for any advice or insight.

    CWE

    P.S I'm a new user from College Station, TX! This is my first post!


    Why all these aberrations?

  2. #2

    Join Date
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    Re: Why all these aberrations?

    That is a common problem when shooting a dark subject against the light, Cody, but this shot appears particularly problematic.

    I expect someone else will be able to give a scientific explanation but I suspect that your lens arrangement certainly isn't helping.

    Were there any other obvious reasons for the light problem. Eg, shiny clothes or reflecting surfaces? And were your exposure settings correct?

    Sometimes this sort of shot responds well to using Fill Flash, although that can cause other issues unless you are careful.

  3. #3

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    Matt

    Re: Why all these aberrations?

    I took a peek at the EXIF data for this photo and I notice that the f stop is reported as being 0!!! Well, I'm guessing that's an error that comes from the teleconverter you were using. What I mean is, the camera and objective can't communicate with each other through your teleconverter. It was either incorrectly fitted or it isn't compatible. Either way, I think the converter is responsible for incorrect metering of the scene - although, given that you used spot metering and the tree is nicely exposed, it could just be that you were not pointing the camera the right way when it was making its calculations for aperture priority shooting.

  4. #4

    Re: Why all these aberrations?

    I took a peek at the EXIF data for this photo and I notice that the f stop is reported as being 0!!!
    EXIF always reads zero with a manual lens. The aperture is set on the lens ring which is not electronically coupled to the camera.

    With reference to optical adaptors (which you must have for the FD mount lens)
    Most included optics are not the best quality, if they are even coated at all, and they will change the lens' original formulation. Thus it's possible to introduce issues with ghosting, distortion and chromatic aberration.
    You can read more HERE . I suspect the adaptor optic is giving you the problem in certain lighting conditions. Try a different manual lens where optical conversion is not required - the Zuiko 50mm f/1.8 works well with a plate adaptor and you can pick the lens up for around 20

  5. #5
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    Cody

    Re: Why all these aberrations?

    Thanks for all of your input, I think everyone made some valid points.

    The FD/EOS mount I was using was a $20 model from B&H, so I'm sure the optics aren't amazing. The B&H model does have a nice feature that the 1.4x optic is removable. (If you remove it you do lose infinity focus, but you are able to get an interesting macro perspective on closer subjects.)

    I have since upgraded to some better lenses, and I was really just using the FD 50 mm as a creative project.

    Next time I'll steer clear of overly bright shots, and maybe I'll get a better effect with less aberration.

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