DWU2 wrote:
Update - I tried again, using a little more force, and the Sigma 150-500 lens clicked in place on the adapter, and works! It's a tight fit, though. I'm wondering if a little lubricant would help, or would that be a bad idea? I don't want to get it on any of the glass, nor do I want to interfere with the electrical contacts. If I did use a small amount, what kind - maybe a tiny amount of silicon lubricant?
No lubricant.
Just use the slightly more force.
I found one of my 3rd party adapters is slightly tighter but not so much as to worry.