Really long adapted lenses on the Fujifilm GFX 50S

This is the 58th in a series of posts on the Fujifilm GFX-50S. The series starts here.

I’ve tested the Leica 280/4 R-mount tele and the 250/5.6 Superachromat on the GFX, and both did well in different ways. I have several longer full frame lenses that might perform credibly — or might not, due to their internal baffling. 

I’m not going to find out.

Why’s that? Because  the GFX doesn’t have in-body image stabilization (IBIS). When I focus 300 mm and longer lenses on the a7RII, I always turn the IBIS on to focus (I turn it off for the shot, though, since I always use these lenses on a tripod when they’re on the a7RII. Without the IBIS, there is too much shake for accurate focusing. When I tested the 250 SA on the GFX, the shake was so bad that I couldn’t reliably focus the lens. The GFX doesn’t have a tripod collar, so the vibration is magnified, but it’s clear to me that I’m not going to be able to  reliably focus a 500 on the GFX.

And, thanks, to the a7RII and its IBIS system, I don’t have to. 

If there are long native autofocus lenses for the GFX, they won’t have the problem with AF turned on. They’ll probably have optical stabalization built in, so they should be okay even with manual focus.