Rolling shutter, known informally as jellocam, is another drawback inherent to large CMOS sensors. Yes, CMOS technology allows you to put a big-ass chip inside a relatively cheap camera (compared with a 3CCD approach), but with the good (Shallow depth-of-field! Low-light sensitivity!) comes the bad (Stuck pixels! Bayer filtering!) and the ugly (Jellocam!). Because large CMOS sensors scan top-to-bottom instead of all at once like CCDs, fast movements and pans can cause the image to appear to wobble. I can show you better than I can tell you:
Dealing with jellocam (same with aliasing) is all about knowing the enemy, and using the right tactics to avoid it. Don’t expect to do any whip-pans with your DSLR, and don’t expect to shoot Blair Witch-style. Treat your VDSLR like a larger motion picture camera — better yet, attach some accessories and a third point of contact (more on this later) to make you treat it like a larger motion picture camera — and do planned, slow camera movements. This instruction alone, more than any technical nugget contained in this guide, will help your productions tremendously! Also be aware of strobe lights, flash photography, or lightning — such rapid changes of illumination can cause partial exposures, where half of the frame is bright and half of it is dark.