02-21-2018 07:19 AM
I have shot a little video with the 28-70 lens on my 1DX MII but I don't often use video. With this setup there is a lot of noise from the focusing motor when using the built in camera microphone.
IS will help with video but if you want really smooth video you will need to use a tripod for critical video. It is far more practical for IS to stabilize an image for a brief shutter opening for photography than trying to take the shake out of video. IS will reduce but not eliminate the shake.