Is this lens aberration?

Discussion in 'Digital Video' started by PRvideoGuy, Apr 6, 2011.

  1. PRvideoGuy macrumors newbie

    PRvideoGuy

    Joined:
    Aug 28, 2009
    #1
    This screen-grab is from footage from an NTSC Canon XL2 with the stock 20x lens zoomed about 1/3 (55mm?)and F1.8. notice that white glow around the dark V of the man's collar. What is causing this? I've noticed it in other footage from that camera, too. The 1st picture is slightly blown-up the 2nd isn't, and they are both taken from the same frame.

    I found this thread about lens aberration and the pictures look similar. http://forums.macrumors.com/showthread.php?t=1130581

    Thank you in advance for your advise and knowledge!
     

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  2. alph45 macrumors member

    Joined:
    Jun 2, 2010
    #2
    pics are small with a lot of compression artifacting so it's difficult to see what's going on and what's caused by what.

    lens aberration usually occurs around the outer edge of the lens.

    do you see this in the viewfinder or just after importing.

    could be blown out whites combined with high contrast (white shirt under black shirt). Could be autofocus hunting. Could be a sensor problem. Lots of "could be's" that require a controlled environment if you want to troubleshoot.

    If your shooting auto anything, turn it off and compare.

    I would do controlled tests using a focus chart and color chart if i wanted to troubleshoot. Test multiple exposures. You could also throw on another lens.
     
  3. PRvideoGuy thread starter macrumors newbie

    PRvideoGuy

    Joined:
    Aug 28, 2009
    #3
    Thanks for the reply!

    I don't see this in the viewfinder. This was taken on manual focus by zooming in, focussing, then back out, so the subject should be in critical focus.

    I'll track down a focus chart and color chart and test it out.

    The camera is set on cine gamma and pressed blacks. Do you think that impact along with the contrast of black to white? It doesn't always have this odd effect when on these settings.
     

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