canon 24-70 zoom ring diameter?
Does someone have the exact diameter of the canon 24-70 zoom ring?
I try to figure out if I can use a zoom gear with my Sigma 12-24.
Sealux doesn't offer one and they guessed the lens diameter is to huge.
But they do offer zoom gear for the Canon 24-70 which is about the same size (Canon states 83.2mm max. diameter which I guess is the zoom ring).
The Sigma zoom ring has 83.7mm. So it should be possible to make one if there is 0.5mm headroom.
Can someone confirm the Canon 24-70 zoom ring diameter? Maybe with a calliper ruler? That would be great! 
Thank you,
Julian
