Got this kind of oddness yesterday on a commercial shoot

[Philip Powell]

I don't know if this is some kind of overprotect, kicking in or what was going on. But we had this very hot (that's what we were going for) slo mo shot of some medical workers running down a hallway. By looking at the histogram, all three channels were clipped, but that was fine for our purposes.

The first frame of the recorded clip was fine, but on the second, the blue channel histogram shifted downward or dropped out all togther perhaps, and this grid pattern appeared. Near the end of the shot (the two jpegs shown) the grid disappears (I'm showing the transition frames), then all the channels go back to clipping and everything looks correct. I.E the female medical workers uniform really is blue.

I could understand photosites turning off to overprotect, that were white (if that's what's going on) but her uniform wasn't that hot.

By closing down we were able to correct the problem, but it was kind of odd, I'm aware of the sunspot protection, but when that happens it's a black spot, correct? I wouldn't know as I've never gotten it. I can't quite get a handle on what when on here. Any ideas?

 

[Philip Powell]

video of problem

video of problem

I had been meaning to post a video of the problem we had but am just now getting around to it.

Download it here.


If you look at the first frame, everything is fine, but on frame two the problem begins and the blue channel shifts downward. Then near the end of the shot it pops back up to normal. (this is viewed in Red Alert's histogram as the histogram in the this downconverted QT viewed in AE aren't behaving in the same way for some reason.)

As I stated above, we were clipping clearly, and, and that was fine for what we going for on this shot.

We fixed the problem by slightly closing down.

What I'm trying to find out is, is this some sort of protection kicking in or it is a "bug"? And if so, what kind of protection, the sunspot protect, is usually something that happens locally, i.e over the sun, not image wide as this does.

Looking at the histogram the the blue channel doesn't seem to "shut off" as I first thought might be happenning when I saw the grid pattern at ful rez. (see stills above.) It seems to shift lower.

I'm just trying to figure out the whys of what went on here, as my client asked me why the Red did that and I couldn't give a good answer. I like to have answers. :mellow: