ND filter wheels on video cameras are quite convenient to quickly control the light intensity entering the camera and work at an optimum aperture. I don't picture myself constantly putting ND filter on and off the lenses on the 5D. So, if not for using ND filters, what do you guys do to mimic ND filter wheels when moving between various light conditions? Switching ISO settings, shutter speeds?

I use the Fader ND (but there are other brands that work great too) which lets you adjust the stops of light gradually (it's great to use while filming if you need to make a small adjustment on the fly as you won't see such a drastic change all at once). When I'm feeling too lazy to put the filter on though I tend to adjust iso first, as the lower the iso, the less grainy the image will be. If I still need to stop down after that it depends on the look that I am going for if I want to adjust the shutter or the aperture. If I am looking for more depth of field, then I leave the aperture wide open and increase the shutter to whatever speed is necessary to get the correct exposure. If the depth of field is not important to the shot then I close down the aperture and leave the shutter at double the frame rate (1/60th for 30p, 1/50th for 24p).

Fader ND is the way to go. It is wonderful to be able to control the exposure without having to change aperture, shutter speed or ISO, and the Fader is much more convenient than fixed ND filters, whether screw-on or slot-in types.

Richard

On a bright daylight definitely have your nd filter on or you will be sorry (at least for video).
I have fader ND and few fixed stop nd filters and my preference is to have fader nd for its ability adjust the stops on the fly.

If you don't have nd filter available, you'd adjust the iso and then shutter speed.