would it be better to use a 5d mark 3 for manual focus rather than a 6d?

[Sebring5]

Would it make any difference?

[diverhank]

If you don't use the superior autofocus of the 5D3, there is very little advantage to using the 5D3...it's viewfinder is a bit better and it's bigger and more robust but that's about it.  The 6D also has a builtin GPS and wireless, something I wish the 5D3 would have.

[Sebring5]

Lens are Zeiss Apo Sonnar T* 2/135 ZE and  Canon TS-E 17mm f/4L. 6d has Eg-S focus screen installed. This could also be installed on 5d Mark 3.

[ebiggs1]

There is no instance where I would prefer the 6D over the 5D Mk III.                    Except cost!

[Skirball]

---

@Sebring5 wrote:

Lens are Zeiss Apo Sonnar T* 2/135 ZE and  Canon TS-E 17mm f/4L. 6d has Eg-S focus screen installed. This could also be installed on 5d Mark 3.

---

Lenses won't matter.  Anything you can put on a 5d3 you can put on a 6d.  Diverhawk summed it up nicely, the only differences between the two cameras are the autofocus systems, size, cost, and wifi/gps.

[hsbn]

I don't think you can replace the focus screen on 5DM3.

[Sebring5]

I can send you the installation instructions for changing 5d Mark 3 focusing screens if you wish. 

[hsbn]

I can google it fine. But it's not swap-able easily like the 6D so no thanks.