at 24mm, i would like it to stay at or above 1/50. at 200mm, 1/200 would generally be fine for me.
i wish you could set it for a few different focal lengths instead of a single deault. 16, 24, 50, 85, 100, 150 & 200mm would be cool
It calls "M" mode in 5D III. You control aperture and shutter speed, camera selects best ISO.
When shooting in "M" mode:
1. Indoor or low light shooting, keep an eye on high ISO. My cut off point is 6400
2. Outdoor/day light, keep an eye on exp comp