mr. sullen Posted March 7, 2008 Share Posted March 7, 2008 http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=00Ohc3 Link to comment Share on other sites More sharing options...
photography by a.f. smith Posted March 8, 2008 Share Posted March 8, 2008 I didn't get a chance to read every post and every response, so I don't know if anyone floated this idea yet, but here goes . . . Most gyms use sodium-vapor lights. These generally run on cycles of 60 per second here in the US. (50 in most European countries) What does this mean? Well, sodium-vapors actually shift in colour over the course of their cycles. Many have a "spike" in which the colour shifts dramatically, but for an imperceptibly short period. This would be very hard to capture intentionally, BUT, if you're shooting at a very fast shutter speed and click the shutter at the right thousandth of a second, the "spike" could be happening for the majority of your exposure, effectively shifting your colour. If the spike takes up half your exposure time , your colour will still shift, but less dramatically. To avoid this, you should shoot at 1/60th of a second if at all possible. That will guarantee that each exposure contains a full cycle, and therefore, the spike will exert the exact same influence over every photograph. (You can also use 1/30th of a second to capture 2 full cycles, 1/15th for 4 and so on) Motion picture folks can relate to this with fluorescent lights. NTSC video is recorded at 30 frames per second. (Actually 29.97 but close enough) making the shutter speed of most video cameras default at either 1/30th or 1/60th of a second which gets along just fine with fluorescent lights. However, most people shoot film at 24 frames per second, making the shutter speed 1/48th. This will obviously not sync with the 60 cycles per second the light is running at, and each frame will contain a full cycle and part of another, causing anything lit by fluorescents to flicker. (Unless you?re suing fluorescents designed for motion picture work, such as Kinos.) This is because, over the course of a cycle, fluorescents vary in intensity even more than sodium vapors vary in colour. Hope the post was helpful. Link to comment Share on other sites More sharing options...
colinsouthern Posted March 8, 2008 Share Posted March 8, 2008 Unfortunately, in many cases "gyms = people in motion", and 1/60th isn't going to freeze that motion. It's much easier to color correct a "spiked" shot taken at 1/640th than it is to fix motion blur from a shot taken at 1/60th :( Link to comment Share on other sites More sharing options...
photography by a.f. smith Posted March 8, 2008 Share Posted March 8, 2008 You're right Colin. My brain must have been locked in a technical gear rather than an aesthetic one. Link to comment Share on other sites More sharing options...
fullmetalphotograper Posted March 8, 2008 Share Posted March 8, 2008 There is one more factor to add to this in a gym you are talking multiple lights and different ages, depending on how old the gym is. The flicker might be an issue with one light or two but multiple sources, it far less an issue. Best thing to do is shoot raw and do a custom white balance. Link to comment Share on other sites More sharing options...
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