Just finished changing the rear standard on my Cambo Actus to the wide angle (ACB-310) replacement that allows use of wide angle LF lenses. Thanks to a well illustrated tutorial courtesy of Steve at CI I was able to complete the change over with a minimum of hair pulling and cussing. Sounds at first like a trivial task - just remove one small set screw from the standard remove existing standard and replace. The gotcha is that there is a small ball bearing hiding underneath that is seated on a spring that will fly out when the pressure is released. Worst part is trying to hold the greasy little ball in place when putting on the new standard. the good thing is that I can now achieve infinity focus with my wide angle lenses. The bad part is that if I want to use longer lenses and/or have the ability to rotate the A7r for portrait orientation I will have to suffer through another change over because the wide angle standard has a fixed bellows and there is no option for rotating the camera. Just tried a couple of indoor quick tests with a Rodenstock 45mm APO-Grandagon to check tilt angle and DOF. Works well and as soon as it warms up a few degrees I'll get back outside and try some landscapes. The small images below link to the full size originals.