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When is Nikon AWB sampled?
Curious if auto white balance is only sampled during the first stage of the button release and locked. Subsequently, any electronic flash (more blue) later used may not be correct if the scene has different (warmer) Kelvin and was locked prior? Or does the camera seeing the flash - if it works via a PW or other brand - reset the Kelvin higher? Just wondering as my early AM shoot using AWB turned out very warm even though flash was used. Sep 17 14 10:38 am Link When ? I do not know if it is before, during or after the exposure or if reading time is consistent between base-end to top- end models. Do a simple test. Flash head with tungsten modelling light on, camera in AWB, compare tungsten lit shot with flash lit shot. If WB changes for the flash then it must be during or after exposure. If it is during the next uncertainty is at what phase of the flash being triggered is it read. If you use a custom in-camera reading from a WB target ( my standard practice ) then the potential issue goes away and is replaced by consistency. Sep 18 14 01:03 am Link Depends. If the flash is a nikon flash, on the hotshoe and in ttl mode, then I think the camera will factor it in. Heck, my SB-900 even came with electronically encoded filters so the flash and camera know if I have a tugsten gel on it or not. If the flash is off camera, or non-nikon, it will not be factored in. In my experience AWB doesnt work well in mixed lighting conditions where daylight, flash and room lights are all mixing. Sep 18 14 01:43 am Link Thanks all. Turned out to be a bit of discussion at Samy's in LA as well. They theorize the AWB is done "prior" to the image being sensored, and any software tries to generate a Kelvin off some gray value "after" the shot and maybe why any 3rd party software generates some differing Kelvin numbers as well as differing hues too which complicate the matter. Fwiw, Nikon didn't even mention Kelvin in Capture NX2 since that software used some Blue/Red intercept for determining gray. Everyone else applies some Kelvin value with some means to get it (Slap a general corrective color to it all and call it "Good 'nuff."). Now Nikon comes along with Kelvin in Capture NX-D which differs from Adobe's Camera Raw formula. Another non-standard among the makers. So I got pissed off and bought a Sekonic C-500 Color Temperature Meter since they had one of their "We pay the sales tax" weekends running that saved me maybe $109 from the bloody cost of the thing. Reads down to 10 Kelvin within its working range too (That Sekonic doesn't mention in their spec's. E.g. You can't see 5,251K, just 5,250K etc.). For fun, I just read my SB-900. Full power 1:1 reads 5,940 Kelvin. 1:128 power reads 6,550 Kelvin. Seems a bit colder than I thought it would be. Longer duration means warmer I guess than the clipped 1:128 power. Oh, well.... Sep 18 14 06:52 pm Link GRMACK wrote: I carry a color meter in my bag. I find it to be incredibly useful. Sep 18 14 07:03 pm Link GPS Studio Services wrote: They were in a quandary about a burst mode in the Nikon and how it handles AWB between shots - if it can. Sep 18 14 07:20 pm Link It is amazing what you can find out with a color meter. I use a Minolta, rather than Sekonic, but it is quite accurate. I never realized precisely how much variation there was or how much the environment actually affected the temperature until I got the meter. I always had a sense but it wasn't accurate until I could take measurements. Sep 18 14 07:46 pm Link |
