Have 5D3, will shoot... but which lens?

[JPAZ]

+1 on what's been said.  Replace the 17-70 with the 24-105.  This is close to the same "effective" focal length due to the change from APS-C to FF.  You'll give up a little in the speed but, having come from a 50d myself, there is no comparison between the noise levels between that body and the 5diii.  You can easily shoot much higher iso without an issue. 

[AudioGlenn]

I think to get the best AF response from the 5D MK3, you need to use the newest glass...
I sold all my L primes and the 16-35 F/2.8 II because the 24-70 F/2.8 II is better than all of them combined.
I particularly dislike both the 16-35 F/2.8 II and the 24-105 F/4 because they are not sharp enough for my taste.

The 24-70 F/2.8 II is another thing entirely.
I must have got a good copy because I got another copy of the Sigma 35mm F/1.4 and I think the Canon is sharper @ F/2.8.

The newer IS primes are all very good, very sharp and focus much better than old glass too.
They just have a 2 dimensional rendering that I don't care for.

I'm currently down to the 24-70 F/2.8 II, 70-200 F/2.8 II and Sigma 35mm F/1.4, which are arguably amongst the sharpest Canon lenses available. To be a prime lover and end up with mostly zooms is a shock to me, but the Canon primes are all old and need updating and in the normal range, the 24-70 is as good or better than everything available (and yes, I had a 24 F/1.4 II and immediately sold it when I got the 24-70).

My advice - save up and get the 24-70 F/2.8 II - it really is made for the 5D MK3, IDX and 6D

ET

+1

[Marsu42]

My advice - save up and get the 24-70 F/2.8 II - it really is made for the 5D MK3, IDX and 6D

-1 ... the af on the 6d cannot use the enhanced precision on the latest Canon lenses like 70-300L, 24-70L2 - see the lensrentals review on the 6d af: 6d is better than 5d2, but 5d3 is like contrast af.

That doesn't mean the 24-70L2 isn't a good lens for the 6d, but part of the money is wasted in this combination: the 5d3/1dx shines here with all doublecross sensors while the 6d only has a non-cross horizontal line @f2.8, i.e. *no* real cross sensor at all. Thanks, Canon.