yeah with tubes its CLOSE and thin dof. I used to my my 85L with 25mm of tubes and got a few keepers. Now my 50 with a 12mm tube seems to be about right. The focus peaking on the a7r really helps.
I am waiting for 12mm and 20mm tubes to use them on 50 and 85, we'll see
the 85/36mm combo should rather be worked from a tripod, which I am often reluctant to do.