I bought my J3 specifically to use it wide open to get the very tight DOF. Unfortunately, I have had to do some experimenting to determine which body to use it on to get accurate readings from the RF. With my Zorki 1, the focus is at 0.9 m when the RF indicates 1.0 m. However, with one of my Zorki 4's it is spot on. So the simple solution will be to just use it on that body. On the other hand, the Zorki 1 works fine with an Industar 61 L/D. Go figure.