RE, thanks for the images. here is my theory. You lit the background with one light from the right side. (If you used two lights the one on the left was powered way down, malfunctioning, much farther from the background or aimed in the wrong direction.) The background light on the right side of the canvas either was aimed in such a way as to allow a bit of stray light to come directly towards camera or lit the edge of the canvas with a very very very hot spot. you shot the lad facing right first (as in example one) when you moved him to face left (as in example two) he didn't spin in place but rather scooted over which brought your camera angle more to the right including more of the hot spot on right side of the background in your viewfinder which caused more flair which caused loss of contrast and an overall blue tint. (both images suffer from flair, do you have good lenses?) One thing that still confuses me is that the blue boy image (test#2) seem slightly underexposed as well. This begs the question, "Were you shooting too fast? Were the packs fully recycling?" Could this cause a colour shift? I know that shooting at a shutter speed which doesn't accommodate the entire flash duration can cause a color shift but sadly I don't know if firing an incompletely recycled pack will do the same thing. I am sure someone here knows that answer. r
