Originally posted by Bengan
but the photos show that the converted mount has a more pronounced bevelled edge which is how you can distinguish between the two.
I beg to differ. Yes, the non-bevelled edge is an indication for an unmodified mount, but it is as such
not an indication of the necessity to modify the mount.
As I've already stated, the depicted non-modified mount (of your 8-16) is perfectly in order and needs no modification at all. The thing is, Sigma uses different outer diameters on their bayonet rings, and those that have to be modfied, are really huge in comparison to those that don't.
Attached is an image of my Sigma 70-200/2.8 before it's modification. When you compare the outer diameter of the bayonet flange to the diameter of the circle, on which the contacts are aligned, you can see the
vast difference to the bayonet flange of your 8-16.
What I deem very good service is Sigma's handling of that issue - my lens is utterly and completely out of any kind of warranty, yet it was serviced for free (not only getting a new bayonet ring but also a vital firmware upgrade needed not to freeze the K-1).