What is the difference and how do you identify a Bronics ETR-S back?
I've seen them described as: early style, late style, ETR, and ETR-S, ETR-Si, and ETRS n.
the earliest backs have only a single latch. late backs have 2 latches and black dardkslide handle. newest model has 2 latches and grey darkslide handle. also the rewind lever differs. on the latest it is a proper lever, on the earlier it's a half-gring thing.
the only big difference is the darkslide. the grey handle one is a locking darkslide (cannot take it out of a standalone back).
Any of the backs will fit any of the ETR versions. I have a mix of early single release and dual release backs andboth work well. I'd not lose sleep over which you have. The 2nd release was added b/c there were some complaints that it was too easy to open the back accidently. The way the single release catch works, whom ever had the issue had to really work at it or failed to correctly close the back.