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White balance & exposure

doemoezidoemoezi Registered Users Posts: 13 Big grins
edited April 8, 2011 in Finishing School
In some books they advice to set the most correct white balance because it is of influence on the exposure.
Anyone who knows more about it?

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    jheftijhefti Registered Users Posts: 734 Major grins
    edited April 3, 2011
    If you are shooting raw, I'm not sure it makes much of a difference. My understanding is that WB is applied in the jpeg conversion process, and to the raw pix as an 'as shot' presentation. In any case, I have never worried too much about WB when I am shooting, as I always shoot in raw format. Probably there are others here who know more about this. I am curious to know as well.

    All that said, I did notice a bizarre WB phenomenon one time, when shooting basketball in a poorly lit court with sodium vapour lights and very light cream colored walls. Every now and then I'd get these weird gradients in color and intensity that should not have been there. I was shooting with a 5DmII, without added photography lights. Only happened once...
    http://johnhefti.com/
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    colourboxcolourbox Registered Users Posts: 2,095 Major grins
    edited April 3, 2011
    What I understand is that there is an effect, and there are specific strategies some photographers use to optimize white balance for most accurate exposure. In Googling it I came across these links. I'm not offering any other conclusions because I don't yet understand everything in those discussions and am still reading them, but you can read them and know that smart people have given it a lot of thought.
    http://www.luminous-landscape.com/forum/index.php?topic=49859.0
    http://www.luminous-landscape.com/forum/index.php?topic=22250
    http://www.guillermoluijk.com/tutorial/uniwb/index_en.htm
    http://www.luminous-landscape.com/forum/index.php?topic=22062

    As for the posts saying "it doesn't matter," we are not talking about whether you have to set WB in camera to get correct WB in the end. We're talking about whether the WB you set in camera causes the in-camera histogram to not report clipping correctly, therefore not reporting raw exposure correctly and creating the possibility of clipping of at least one channel. Because the in-camera histo is based on producing a JPEG with camera controls, not a raw.
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    jheftijhefti Registered Users Posts: 734 Major grins
    edited April 3, 2011
    colourbox wrote: »
    As for the posts saying "it doesn't matter," we are not talking about whether you have to set WB in camera to get correct WB in the end. We're talking about whether the WB you set in camera causes the in-camera histogram to not report clipping correctly, therefore not reporting raw exposure correctly and creating the possibility of clipping of at least one channel. Because the in-camera histo is based on producing a JPEG with camera controls, not a raw.

    Thanks Colourbox, that is good to know. I hadn't thought about what format the histogram represented. I just assumed it was overall intensity (or each of the color channels) of the image in RAW form . I guess it makes sense for it to represent something closer to the final image one wants to create. But does the WB have any actual effect on the captured RAW image? I can understand that a misleading histogram might cause the photographer to set the exposure incorrectly; but for a given exposure, does changing the WB on the camera have any effect? i wouldn't think so, but I still have a lot to learn about this subject...
    http://johnhefti.com/
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    chasgrohchasgroh Registered Users Posts: 50 Big grins
    edited April 3, 2011
    jhefti wrote: »
    If you are shooting raw, I'm not sure it makes much of a difference. My understanding is that WB is applied in the jpeg conversion process, and to the raw pix as an 'as shot' presentation. In any case, I have never worried too much about WB when I am shooting, as I always shoot in raw format. Probably there are others here who know more about this. I am curious to know as well.

    All that said, I did notice a bizarre WB phenomenon one time, when shooting basketball in a poorly lit court with sodium vapour lights and very light cream colored walls. Every now and then I'd get these weird gradients in color and intensity that should not have been there. I was shooting with a 5DmII, without added photography lights. Only happened once...

    ...when you're shooting in heavy-duty artificial lighting, the mechanical effect is "cycling," as in the hertz range for the particular lights. Like, 60hz will cycle 60 times a second, thusly you can get quite a few variants in color... problematic, and very difficult to correct down the line, too. I shoot inside gyms often, and know to grit my teeth and bear it! (...my info comes from a guy who's been doing it for years...he's helped me to relax!).
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    jheftijhefti Registered Users Posts: 734 Major grins
    edited April 3, 2011
    chasgroh wrote: »
    ...when you're shooting in heavy-duty artificial lighting, the mechanical effect is "cycling," as in the hertz range for the particular lights. Like, 60hz will cycle 60 times a second, thusly you can get quite a few variants in color... problematic, and very difficult to correct down the line, too. I shoot inside gyms often, and know to grit my teeth and bear it! (...my info comes from a guy who's been doing it for years...he's helped me to relax!).

    That makes sense, especially when shooting sports where the shutter speed is much faster than the inverse of the cycle frequency. But I've only seen this at one gym, but confess to not shooting indoors that often.
    http://johnhefti.com/
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    pathfinderpathfinder Super Moderators Posts: 14,698 moderator
    edited April 3, 2011
    Color variations when shooting under sodium lights, with shutter speeds shorter than 1/60th to 1/125th secs are not unusual.
    Pathfinder - www.pathfinder.smugmug.com

    Moderator of the Technique Forum and Finishing School on Dgrin
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    arodneyarodney Registered Users Posts: 2,005 Major grins
    edited April 4, 2011
    When shooting raw, WB has no effect on the data (its only a metadata suggestion for rendering a JPEG or if the raw converter can read the data and even then, its a suggestion). Only Exposure and ISO affect raw data.
    Andrew Rodney
    Author "Color Management for Photographers"
    http://www.digitaldog.net/
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    jheftijhefti Registered Users Posts: 734 Major grins
    edited April 4, 2011
    arodney: thanks! that's what I thought. I usually leave WB set to auto, unless I am shooting color-challenged situations like theatre and dance. I then correct in the post.

    colourbox: I learned a lot from those links you sent, not the least is why shooting to the right (which I do frequently) works well, even when there is some clipping indicated on the LCD. I always wondered why this happens--clipping alert on the LCD but not actually blown out in the RAW file--and now I know.

    Does anyone actually readjust the WB calibration on the camera so that the histogram reflect that actual image being recorded? I've just gotten used to how much I can push the exposure to the right, and how much clipping alert I can tolerate before there is actual clipping.
    http://johnhefti.com/
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    arodneyarodney Registered Users Posts: 2,005 Major grins
    edited April 4, 2011
    jhefti wrote: »
    I usually leave WB set to auto, unless I am shooting color-challenged situations like theatre and dance. I then correct in the post.

    Exactly what I do too. Auto often gets me in the ball park, but I can season to taste. If the lighting is way off, might as well specify something closer for the raw converter just so it doesn’t look so butt ugly upon import.
    Andrew Rodney
    Author "Color Management for Photographers"
    http://www.digitaldog.net/
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    IcebearIcebear Registered Users Posts: 4,015 Major grins
    edited April 4, 2011
    arodney wrote: »
    Exactly what I do too. . . just so it doesn’t look so butt ugly upon import.
    rolleyes1.gifroflEspecially if your client wants to chimp, or you're shooting tethered. "Butt ugly" white balance really puts a portrait client off her feed.
    John :
    Natural selection is responsible for every living thing that exists.
    D3s, D500, D5300, and way more glass than the wife knows about.
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    jheftijhefti Registered Users Posts: 734 Major grins
    edited April 7, 2011
    arodney wrote: »
    If the lighting is way off, might as well specify something closer for the raw converter just so it doesn’t look so butt ugly upon import.

    Likewise. When I shoot indoor games under monochromatic light, I almost always specify the WB so that the colors and especially the skin tones look somewhere close to attractive on the import. Makes the post a lot easier too. AWB just makes the skin tones look jaundiced, which I suppose is how they actually look under those lights. Still, not what I want in the final version.
    http://johnhefti.com/
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    malchmalch Registered Users Posts: 104 Major grins
    edited April 8, 2011
    arodney wrote: »
    If the lighting is way off, might as well specify something closer for the raw converter just so it doesn’t look so butt ugly upon import.

    Yes, having the in-camera WB in the right ballpark can help you capture a good exposure too since most camera histograms are based on the converted JPEG preview.

    Or you could use UniWB and have all of your images look butt ugly on import ;-)

    It's about time DSLR makers starting giving us histograms that were based on the actual RAW data!
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