Pentax 55/2 - Strange Color Shift

Discussion in 'Adapted Lenses' started by scott, Jan 12, 2011.

  1. scott

    scott Mu-43 Veteran

    Nov 15, 2010
    I did some quick test photos this morning with a G1 and an SMC Takumar 55mm f/2. I meant to compare sharpness in photos at various aperture settings, but what really stood out was that while all the pictures from f/2 through f/8 had fairly accurate colors, like this:

    View attachment 155647

    ...the photos at f/11 and f/16 looked like this:

    View attachment 155648

    When I noticed this, I did the test again, and got the same results. The light didn't change during the test.

    Anybody have any idea why this is happening? Is it really something created by aperture changes, or could it be some sort of shift in how the auto white balance is treating the scene? Why would that change with aperture?

    Any thoughts would be appreciated.
  2. John M Flores

    John M Flores Mu-43 Hall of Famer

    Jan 7, 2011
    Somerville, NJ
    I think that's very odd.

    You have two suspect - aperture and auto WB. It's easy enough to rule out auto WB by setting it to something else and see if the color still shifts with aperture...
  3. scott

    scott Mu-43 Veteran

    Nov 15, 2010
    Well, I re-did the test with various combinations of auto and manual settings (ISO and WB), and couldn't get it to happen again. Not sure what happened there.