7d exposure consistancy?

PhotoByED wrote in post #11174230
Must be the old magnetic ballast in the lights. Tell them to upgrade to electronic ballast T8's.....

Or just set your WB manually to florescent or correct in post.

Doesn't work to manually fix when one half is good, other half isn't. Turning off auto-iso seems to have pretty much eliminated it.

looks like the flourescent light problem to me.

turning off auto-iso is not going to fix your problem, unless your shutter speeds also changed....

check this out...
http://photo.stackexch​ange.com …ighting-and-shutter-speed
http://blog.tommyimage​s.com …r-fluorescent-lights.html

TeamSpeed wrote in post #11174593
turning off auto-iso is not going to fix your problem, unless your shutter speeds also changed....

check this out...
http://photo.stackexch​ange.com …ighting-and-shutter-speed
http://blog.tommyimage​s.com …r-fluorescent-lights.html

Well I took 300 more after turning it off, and none showed the problem to any real extent, some had white balance off, but that is expected, none of the banded images.

sWampy wrote in post #11174626
Well I took 300 more after turning it off, and none showed the problem to any real extent, some had white balance off, but that is expected, none of the banded images.

What were the shutter speeds? Again, if you use the correct shutter speeds, you won't see the issue. ISO is not the issue, your shutter speeds are and the white balance settings are as well, but if you shoot in raw, you can correct for some of this in post later. In any case, if you have it solved, great! It is still good to understand how messed up CFLs can be for photography and how to deal with it.

It's an issue with the timing of the shutter curtains and their speed relative to the frequency of the light pulses from the flourescent lights. The photos look like what happens when you use a faster shutter speed than the x-sync for a flash pulse.

sWampy wrote in post #11174626
Well I took 300 more after turning it off, and none showed the problem to any real extent, some had white balance off, but that is expected, none of the banded images.

As many have pointed out, this is an issue with high shutter speed + fluorescent lighting. Anything faster than 1/100s (and I'd even argue faster than 1/60s) will increase the likelihood of you catching the light during a bad phase. That doesn't mean that every-so-often, you won't get a nice, clean, evenly-lit shot at 1/500s or 1/1000s.

Our eyes are not sensitive enough to catch the flickering of the lights, but the camera shutters are more than capable of doing so.

What were your settings when you took the camera off auto ISO? Because I seriously doubt the next 300 perfect images were at 1/500s.

jwcdds wrote in post #11174766
(and I'd even argue faster than 1/60s)

That's the point. In this part of the world we use 50Hz, so 1/50s would be long enough to catch one full period of the AC, with two zero crossings and two peaks at 325V (absolute value). The exact numbers differ for different electrical systems - these values are correct here - but the principle is the same everywhere.

I have a X-ray viewbox where I often will take old X-rays forwarded by other dentists, take photos of it, and then import into the patient's digital charts. (I've found doing so to be much faster than scanning.) And of course the viewbox uses fluorescent tubes and I have to set the camera to 1/60s. Thank goodness for the IS on my 100L.

A couple of years ago, when I started doing this, I'd run into the same issues as the photos posted by the OP. That's when I learned about how crappy fluorescent tubes are for photography.