White Balance issue?

Discussion in 'Digital Photography' started by romanaz, Feb 10, 2009.

  1. romanaz macrumors regular

    romanaz

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    #1
    Okay, so last saturday I shot another Olympic weightlifting event, this time with my newly purchased 50 f/1.8 II lens. I've been capturing and working on the some 3500 images and I've noticed a trend I didn't see in camera that day... from shot to shot, the color cast or white balance seems to change...

    one shot will be perfectly white balanced with good skin tones, the next one will be slightly off, with the skin tones way to pale. All the colors seem to be affected, not just the skin tones, the green banner in the background is as well...

    I'm confused as to why this is occurring, I can fix this in post, but it'll be a pain in the ass. Does anyone have any idea why this would happen? Maybe a different amount of light hitting the sensor? or something, I am baffled.

    here are two back to back shots taken, unprocessed save for my watermark.

    if anyone can offer an explanation, that would be awesome, I'm intrigued by this.
     

    Attached Files:

  2. Abstract macrumors Penryn

    Abstract

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    #2
    Auto White balance sucks, and so do the presets. I don't know what else to tell you. You can manually set your white balance under the lighting conditions used in the shot by bringing a "gray card", or even simpler (but not as good), a white sheet of paper and setting your white balance using that. Instructions on how to set your own WB will be in your camera's manual.
     
  3. romanaz thread starter macrumors regular

    romanaz

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    #3
    should have mentioned that I did white balance to a white sheet of paper for this. Its definitely not autowhite balance.
     
  4. toxic macrumors 68000

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  5. leighonigar macrumors 6502a

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    #5
    That would be my suggestion also, perhaps that the light changes in colour throughout its cycle. Unhelpful if this is the case.
     
  6. ChrisA macrumors G4

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    #6
    Yes. fluorescent lights flicker. They turn off and on at about 60 times per second. I think it may depend on pure chance of how the shutter and AC mains timing interact. Your lighting setup changes as one fluorescent tube is bright and another goes dim

    Try exposures that are longer than 1/60th or if you are in Europe 1/50th.
     
  7. Abstract macrumors Penryn

    Abstract

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    #7
    Or how about 1/30th or 1/25th? I'm not sure if I'm thinking of the same thing as you are, but doing this would encompass 2 "blinks" in each photo he takes. Isn't that better? I probably don't know as much about the WB setting as you do (actually, I'm sure I don't).

    I guess shooting at 1/30th or 1/25th may also result in motion blur, so what I said may not be a good idea anyway...
     
  8. romanaz thread starter macrumors regular

    romanaz

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    #8
    good point, if you look @ the top of the picture, we see what I'm pretty sure are fluorescent lights. I was shooting @ 1/200 so maybe it was catching it just right. Nearly EVERY shot, the next one is slightly different.

    oh well, guess I'll just correct it in aperture.
     
  9. Phrasikleia macrumors 601

    Phrasikleia

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    #9
    This sort of thing is the reason I always shoot in RAW. Usually one click of either the auto-levels or the auto-levels-separate button in Aperture is enough to make an image 90% perfect, and only minor tweaking is required to make me happy. And for those shots that are really tricky, at least the RAW format gives me lots of leeway for fixing them.

    When you let the camera's processing make decisions for you, be it white balance or sharpening or whatever, the amount of post-processing that is required to fix it can be extensive--and the results may not ever be what they could have been with all of the RAW data to draw from.
     
  10. GotMyOrangeCrus macrumors regular

    #10
  11. H2Ockey macrumors regular

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    #11
    gotta agree with several here.
    Cause: Fluorescent light cycles - nothing you can do in camera will get the same results with every exposure based on what I assume you're shutter speeds must be to shoot the subjects.

    Solution: Shoot RAW and fix later. Depending on software/camera combination this could be a relatively quick batch fix.

    I would still use one setting rather than Auto, as the auto WB is going to try and adjust each exposure... though it might do ok having a consistent starting point is better.

    I've experimented with WB on some occasions when lighting is hard and i must say sometimes Auto WB does a really good job, BUT fluorescent lighting is not one of those times.
     
  12. GotMyOrangeCrus macrumors regular

    #12

    As good of a job as your auto WB did, you will get the optimum results every time if you take the time to evaluate your subjects lighting and set it yourself. In all honesty this should be one of the first things all digital photographers should learn. Too many digital shooters rely too much on their camera.
     
  13. Abstract macrumors Penryn

    Abstract

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    #13
    He said he set his own WB. ;)
     
  14. jaseone macrumors 65816

    jaseone

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    #14
    Err if it was due to the cycles of the fluorescent lights how exactly would that help?
     
  15. ChrisA macrumors G4

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    #15
    Mathematically, if you average a sine wave over one, two or 100 cycles you get the same result, zero. Shoot at exactly one cycle and it should work.

    But why not just shoot RAW? then you can worry about this later. All you really need to do is make shure there is some white object in the scene in the same light as your subject then you have the EXACT same thing as if you shot a white card in the shot.
     
  16. leighonigar macrumors 6502a

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    #16
    Maybe he did shoot RAW - he said he could fix it in post, certainly. He was just irritated because he has to spend the time fixing it in so many shots.
     
  17. Milessio macrumors newbie

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    Nov 20, 2008
    #17
    The lights flicker at x2 the mains frequency, so shooting at 1/60s = 2 cycles.

    If the problem actually is the lights, increasing use of energy saving bulbs in the home is going to make things interesting, unless one always uses flash.
     
  18. mrgreen4242 macrumors 601

    mrgreen4242

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    #18
    I was goign to ask if he was using a flash. I notice this problem occasionally with my D40 and SB400 combo. The SB400 recharges really fast so I can shoot flash exposures less than a second apart... for awhile. As the batteries heat up the recycle rate gets slower, and I've noticed that the flash will fire slightly less brightly on the 4th or 5th rapid exposure. This throws off my WB a bit, or at least has the same affect as the WB being off. If you were using a fill flash and shooting lots of sequential photos the flash could have been slightly off on the second or third photo causing slightly different colors.

    Or it could be what everyone else is saying. :p
     
  19. romanaz thread starter macrumors regular

    romanaz

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    #19
    no flash was used by me, but some guy with a Nikon was using one and messed up a few lifters and a few shots of mine and the other people trying to do sequence shots.

    The first one here, was going for an American Masters Record and luckily held onto the weight even though she was mostly blind after the flash, this other guy, not so lucky, he lost his concentration when the flash went off and lost the bar behind him.
     

    Attached Files:

  20. H2Ockey macrumors regular

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    #20
    Wow, that is nearly unbeliveable! I don't care what sport it is a flash directly into my eyes would make me very unhappy. With 250lbs of steel above my head??? I would have had a hard time not walking over and smashing that guys camera. Besides that bouncing or difusing the flash would have made for better lighting anyway. argh bad technique on so many levels.
     

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