When I bought the Sony A7 I put a Kiwi adapter on it and tried using my old 24mm and 28-200 and both Focus Peaking and Focus Zoom still worked. Today with that same adapter I was looking at a Nikon 50 1.4 AIS. Peaking came on but the Focus Magnifier didn't. Should all Lenses activate the Focus Magnifier or how would I know which ones will and won't?
Alright, guess I was mistaken because Focus Peaking works by default but the Focus Magnification doesn't work with adapters.
However, I found online a workaround and just set it up to test - worked perfectly.
Full detailed instructions head to Silvermac at http://www.silvermac.com/2015/07/29/sony-a7-ii-using-mf-assist-with-the-lens-adapters/
Basically, turn Focus Magnification on and the time to No Limit. Then go to Custom Buttons and choose one to use for it. Hit that button once then the Center Button and you're in business. Works great.