I'm starting to notice a dark area on one side of the frame when shooting my 1Ds MkII in manual mode at 1/250s at around f/16 with Speedotron strobes. I use Pocket Wizards to fire the strobes. Attached is a sample of the problem. Am I misunderstanding the X-sync speed of the 1Ds MkII? The thing is I've been shooting at 1/250s for a while and never saw this before - and I'm wondering if my shutter is having problems.