A couple of months ago I bought the new Canon 5D MKIII and tested out the slow motion with it and came out with horrible results but after some different configurations I finally everything out. Originally I was doing 60fps but with a 1/1600th shutter speed which was too fast of a shutter speed for the actual camera to process. So after talking with other video guys such as Matt Crane he said he was doing 60fps 1/125th shutter speed so I tried it. The results came out a little better but he was shooting with a 7D and with with the Mark III you have 2 different types of compressions ALL-I and IPB. ALL-I is the highest quality but can take up alot of space on your memory card but if your not shooting entirely in 60fps you have nothing to worry about for Storage. IPB is higher compression which can cause less quality and takes up less space for the memory cautious individuals. So after multiple test I found out that Shooting All-I, 1/125TH shutter at 60fps was the best result and here is some test shots to show you.