I got a #2 (82mm) RB extension tube in the mail today. I will experiment with it using my 127/3.8 on an RB67 Pro S. A 180 is on its way here. I will try to decide whether to get a 65 after that or a 140 macro. For hand held use I prefer my Bronica GS-1s but the RB is much better for closer work.