Cheers :)

Hi Vladimir,

I always shoot on M as this gives you full manual control of Shutter/Aperture and ISO. If you use the other settings, one of them will vary automatically when the light reading changes. With the M setting you can set your Shutter to say 1/50th Sec, Aperture to say f3.5 and then adjust the ISO accordingly to get the right exposure, say ISO400. It's nearly always a good idea to keep the shutter speed consistent ie: 1/50th sec (or 1/60th if shooting 30fps) Unless you want a deliberate effect from a faster shutter speed. The changing light as you zoom out is a different issue and is them same for all but the most expensive zoom lenses. The 18 - 135 lens is a F3.5-5.6 lens which means at 18mm is operates at widest F3.5 and at 135mm it operates at widest f5.6. Its called ramping. Ramping is when the diameter of the lens glass is not large enough for a lens to maintain the minimum F Number across the whole zoom range. Ramping occurs on normal video cameras but is compensated for in the video cameras exposure settings. Video DSLRs are quite primitive at the moment, so my advice would be zoom as little as possible in shot and use the DSLR's strengths of great definition and color reproduction. Hope this helps...