I received my brand new MK III a week ago from B&H, if it is a green/blue/red or whatever "dot" I have no clue, the number is 569478. I have read and heard a lot about the problems with this body and was not sure if I was being stupid buying one. At least I still had the 1Ds Mk II if the MK III "failed". As I had a 10 day window to find any problem(my courier going back) I have tried to find if there could be a problem with the camera this last few days.
I have not had time to go out for BIF but did give the AI SERVO AF and 10FPS burst mode a good work out with a dog running away and back to me at a fairly high speed several times. My C.Fn III -2 setting was on medium slow. The tracking was spot on. The only time I consistently seemed to get a OOF shot was if the dog was running staight towards me at high speed and then suddenly slowed down, one frame would be OOF but the next one will be sharp again. It is as if the camera would be tricked by the sudden reduction of speed. I am happy with the performance and is sure if I use a faster setting that I will not "trick" the camera so easily. One thing that did impress me was the IQ of outdoor images in harsh sun/shadow conditions. This camera blows my 1Ds II away in those conditions. I shot with all the settings on neutral(no highlight tone priority either).
Then I did a few hundred shots in studio. Although I did get some nice images I feel that the 1Ds II is still the "better" camera for studio/portrait work. Natural low light/window light performance is really good with the Mk III.
The controls/buttons is nice and the only thing that irritated me a bit is that you have to go into the menu if you want to delete "all" images on the cards. I love the ISO button.
Taking a bit to get used to the "harsh" sounding shutter also after shooting so long with the silky smooth 1Ds II.
So yes for the time being I am quite happy with the camera and think that it was money well spend.
Any further tips on what to check on the camera will be appreciated.
One of the studio shots at ISO 400 with 580EX II




