What color to gel?

<p>So I'm shooting again this weekend in a room I've shot in a few times. It's roller-derby, so it's fast action but very predictable as far as where the skaters will be. Typically, I'll set up two hotshoe flashes on stands. balancing their color to the lights in the ceiling has been a nightmare, though. </p>

<p>Can anyone provide any assistance in figuring out the best way to gel to match these lights? They seem to flicker between green and magenta.</p>

<p><img src="http://sonicbloom.org/share/lights_room.jpg" alt="" /><img src="http://sonicbloom.org/share/lights_closeup.jpg" alt="" /></p>

<p>The way they cycle, I expect there will be a fair bit of failure, but I'm hoping it's not a completely lost cause..</p>

<p>Thanks!</p>

<p>It's a moving target. Better to shoot RAW, and try to capture a gray/white WB target when the light's at each end of the frequency cycle. That way you've got something you can adjust to neutral after the fact, and that will give you an adjustment you can batch-apply to larger numbers of images that seem to have drifted one way or the other.<br /><br />Your other option is to expose/compose in a way that lets the strobes do more (most) of the work. But you may not have enough horsepower for that with two speedlights.</p>

<p>Thanks, Matt. That's been my approach so far -- take a bunch of shots of my gray card, hope I hit the cycles, and set up a few WB presets in Lightroom. I can usually get away with shooting RAW on my 50D and not outpace the buffer too badly. </p>

<p>So am I best off continuing to shoot with ungelled flashes? Typically, I find that when the skater is nicely lit with flash, the background goes greenish yellow. If I correct for the background, the skater's skin tones go out of whack. What would happen if I gelled 1/4 green or maybe a partial straw? Or does that just complicate a matter that would be better dealt with in post? </p>

<p>You're dead on for horsepower -- I can light an individual skater and darken down the backgrounds pretty well, but then I'd need a few more lights to fill them back in to see the crowd, refs, etc. I've got four flashes to draw from, but still... :)</p>

<p>Try shutter speeds in multiples of 1/60 second in order to capture a full green/magenta cycle.</p>

<p>I think you would find that using an Expo Disc white balance tool would be of huge help in this situation.</p>

<p>Derek - I'd have to keep my shutter below 1/60th to keep a whole cycle, right? I'll keep that in mind when I pick panning speeds, but usually I need to juice the shutter as much as possible to stop action. </p>

<p>Michael - funny you mention that; I was just considering an Expo Disc. It's my understanding that I'd point it at the light source, take a few shots (a few because they cycle) and then be able to set a custom white balance. correct? Any way I could then use this (in camera) to figure out how to gel my speedlights to match? If it helps, I'll have a 50d and a 5d with me.</p>

<p>Set your shutter at EXACTLY 1/60 sec. That will grab exactly 1 complete light cycle. No reason to go to 1/30 (that will just give you more problems), and at 1/125 you only get half a cycle. Hopefully your flash will get the skater frozen well enough that you can expose the background at 1/60 without blurring the edges too much.</p>

<p>Benjamin:</p>

<p>If I were doing it, I'd overpower the ambient fluorescent lights and just go with ungelled flashes.</p>

<p>If you shoot faster than 1/60th of a second, you'll get all sorts of color temps. If you shoot slower, you'll get blur.</p>

<p>Eric</p>

<p>As each light will cycle individually you'll probably never be able to get this 100% correct. I suggest to color meter it, maybe take a couple of readings and average it, then correct your flashes, set grey card balance to the flashes (maybe create a custom profile via X-rite Passport) and run with it. Your exposure will probably drop the ambient down anyways (so it's not that vast grey background). In post i would first correct to your grey card/flash exposure and consider dropping the overheads lights in saturation a bit. </p>

<p>Hal & Eric, I'll play with some shots at 1/60th to get some panning, but I usually find I need to shoot faster. The speedlights help stop the action, but unless I really knock down the ambient, the faster the shutter the better. It'll be interesting to pay attention in post to which shutter speeds cause the most problems for me. <br>

The vast grey background gets filled with 2,000 cheering fans, so I don't want to drop the ambient too far. :) Dropping the saturation is a good call - especially considering I can use an LR Adjustment brush to so easily bring it back up on the main subject.<br>

Mark - when you say "color meter it ... then correct your flashes" I assume a color meter is a piece of equipment much like a light meter, but measures the color of your lights? 'twould be nice to have, but alas not likely for this event. <br>

Thanks for the advice, everyone!</p>

<p>Doesn't the 1/60th shutter assume you are exposing at the start of one of the light's cycles? How can that reliably occur when concentrating on the subjects?</p>

<p><em>Doesn't the 1/60th shutter assume you are exposing at the start of one of the light's cycles? How can that reliably occur when concentrating on the subjects?</em></p>

<p>It doesn't matter where in the cycle you catch the light. Because, at 60Hz, one cycle takes 1/60th of a second, no matter where you start in the cycle, by the time the exposure is done, the light has returned to where you started.</p>