Today i had the opportunity to spend about 1 hour with the 5DMark III and the 24-70 L II and I thought I would share my experience with you guys.
Let's start with the camera:
1. HOLDING THE CAMERA
I brought along my 5D Mark II and by comparison the new 5d is better built especially around the card door area.
The hand grip sits better in your palm due to the curvier shape of the body. I love the new lock on the mode dial that prevents your from accidentally switching from AV to Tv, for example. Great little feature!
The top LCD is also improved by being larger and displaying more items.
One major change from the 5D Mark II is image reviewing. My right thumb was constantly reaching for the magnifier button on the right side. It took me a few seconds to realize that the button was moved to the left side. This is a change that will require some adjustment time especially if you upgrade for the Mark II. On the other hand the new magnifier is faster and you can set the magnification level in the camera menu.
The viewfinder is brighter and visibly larger than the 5D Mark II's viewfinder. I wouldn't have thought 2% made such a big difference but it does!
The same goes for the main LCD. Bigger and, to my eyes, better at displaying colors accurately.
2. USING THE CAMERA
AF: Amazing! I was blown away how quickly and accurately the 5D Mark III and the 24-70 L II combo focused. No hunting, just instant focus as soon as you half press the shutter, regardless of the chosen focus point. I would like to mention that I did not have the chance and the time to test the AF in servo mode nor did I tweak the AF settings. In my opinion this is the biggest improvement over the Mark II.
High ISO performance: As I was not allowed to put my card in the camera I could only judge the image quality based on what I saw on the rear LCD. I did some quick and empirical tests at ISO 3200, 6400 and 12800. Obviously the Mark III is cleaner at 3200 and MUCH cleaner and 6400. I also noticed that ISO 12800 looks usable. Not so sure ISO 25600 would be really useful for wedding photography (in my case).
The new 24-70 L II:
Compared to the original 24-70 it's noticeably lighter and more compact. Unfortunately the weight reduction comes form using some kind of high grade plastic on the lens body which takes away from the robust feeling you get when holding the original 24-70 which is made of metal and glass. This is purely subjective and I'm sure It will be just as tough as the first 24-70. Cannot comment on the IQ of the lens as I wasn't allowed to put in on my camera and take pictures with it.
This is my short review. Hope you find it useful and keep in mind that I did not have the time to further test the camera.
Feel free to ask my questions!