Barry Clemmons 
, Sep 05, 2010; 03:16 p.m.
I shoot a lot of local high school football games, almost all of them at night. A couple of times I have experienced a weird phenomenon at some, but not all stadiums. It happens in both burst mode and when taking single shots. About 1/3 of my shots will have brown tint and will appear to be under-exposed. Sometimes the tint will appear in the top or bottom half of the shot only. I'm guessing that it has something to do with the lights at particular stadiums since it doesn't happen at every game. I am attaching two shots taken 9/100 of a second apart. The exif shows identical exposure data for both, but the histogram for the darker image has shifted to the left as expected.
I normally shoot using Auto WB and get excellent results. My first thought is to start setting the WB manually with an Expo Disc. If my theory about it being the type of bulbs used at certain stadiums is correct, that might not work either if the problem is bulbs shifting through different portions of the light spectrum on a continuous basis. Has anyone else experienced this and if so how did you solve it?
Example of normal image
Barry Clemmons , Sep 05, 2010; 03:18 p.m.
Here is the example of the bad image
Example of poor image less than a second later
C.P.M. van het Kaar , Sep 05, 2010; 03:53 p.m.
Barry,
Do you use spot-metering and/or active D-lighting and/or Auto ISO ?
The second shot seems to be just a bit more to the left from the first shot, and using spot-metering on a (part of) a black shirt ( first one ) could give you different lighting from metering on a (part of) a white shirt, affecting the lighting of the whole picture ....
Tom Weis , Sep 05, 2010; 03:56 p.m.
The mercury vapor lights in the stadium flicker. A custom white balance will get you close most of the time, but there's not anything you can do to totally eliminate WB drift and the associated change in exposure. It helps to shoot RAW so you can tweak your color and exposure later.
Jim Momary 
, Sep 05, 2010; 04:53 p.m.
You are shooting @ 1/500th (exif data). The mercury lights flicker at 120 Hz (2 x 60 cycle per second frequency). Depending on the mass of the filament, the lamp "color" can be variable in that flicker cycle as it is heating and cooling. It may be chance alone that "captures" the serendipity of timing. This is a common issue with fluorescents. The only fix I know about is to capture at least one full cycle, i.e. shutter speed = to or slower than 1/120th. Search thru PNet in discussions about color shifts in gyms at various games.
Maybe somebody else has better insight?
Jim M.
John Tran , Sep 05, 2010; 05:07 p.m.
The EXIF of both pictures are the same: Metering pattern, Speed 1/500, Aperture 2.8. But the pictures are different because the lighting of the scene changed 9/100 of a second is enough to change. Solution? You did get a good picture, didn't you?
Ron Hiner , Sep 05, 2010; 05:15 p.m.
Tom hit the nail on head... The lights change color during the course of the AC cycle. And expo disc won't do you any good.
Check these out... the white balance of the light changes during the course of the exposure.
http://galleries.ronhiner.com/temp/d1scusssion_whitebalance/index.html
Try Jim's suggestion.... shoot at multiples of 1/60 of a second, you should get the full range. (1/60, 1/30, 1/15, etc.) Not going to do you much good shooting sports. I'm not sure 1/120 will do it -- you will only get half the cycle.
Not a lot you can do... if the publication you are shooting for allows photoshopping, you can fix it, or -- what happened to other shots from this series, they were published in black and white.
Jerry Litynski 
, Sep 05, 2010; 07:05 p.m.
The stadium lights: no high school stadium (to my knowledge) has the same lights overhead at two different schools. If you get a little tone in your images, you should be able to live with it: it's football, and not a wedding or a pageant.
Barry Clemmons , Sep 05, 2010; 08:37 p.m.
Thanks to everyone for your responses. It pretty much tells me what I expected, that certain high school stadium lights will present this problem. The week before I shot in a different stadium with the same settings with no issues at all. I shoot using Matrix Metering and don't use D-lighting or Auto ISO. I have also sent an email to Nikon Support, but I expect their response will be the same. The perfect solution would be for all of the high schools to play day games, but that isn't going to happen.
Thanks again!
barry goldberg 
, Sep 05, 2010; 10:22 p.m.
As FYI, this is a huge problem inside many school gyms. I just shoot lots of extra pictures, knowing that I'm going to lose 20% of them due to the light cycling through.
