Bronica ETRSi Back Film Flatness

I'm planning to get a second back for my ETRSi. I currently have the ETRS new style back - the one with two tabs that must be pressed simultaneously to open the back. These are significantly cheaper than the EI back, which has a locking darkslide and replaces the film advance knob with a crank - these improvements are not particularly important to me. However I've also read on Tamron's site (www.tamron-usa.com/bronica/etr_guide.asp) that with the EI back, "pressure roller tension was increased for film flatness improvement".

Have any users of earlier ETR backs have experienced problems with film flatness?

Thanks
Andrew

I have the single and 2 tab backs and never saw anything with my results suggesting any flatness issues. I do not have an EI back but subjectively, the one I looked at seemed to have the same plate tension as I too read what you have read. The key with the ETR series is not to keep the film advanced for any length of time as it is reversed in its winding as to the set. I only wind when I am ready to shoot. I also have never had an issue with the single tab back opening as has been alleged when the 2 tab back came out; I think it was more a cost cutting change as the 1 tab back as a safety lock that the 2 tab and EI backs do not have. I've also NEVER by mistake pulled the slide out so see no advantage to the slide lock. I can not imagine someone doing it unless a total newbie as to MF or the ETR camera. It operates too slowly not to be thinking about each step unlike a few times when I was in a rush and opened the back of a 35mm camera not remembering it was already loadedand forgetting to feel for the load with the wind know/crank/lever.

I'd not worry about what version of the back to buy unless trying to match the set, then the single tab for the ETR and ETRC and early version of the ETRS and the 2 tab back for the early and 2nd version of the ETRS and the EI back for the ETRSi. As I am not worried, I'd just opt for the one in the better condition and try to stay away from backs used by professionals as they probably would exhibit more wear.

Thanks for the detailed answer Brian. I'm not worried about getting the matching back for the ETRSi so I'll probably just get another two-tab back as they are about the same price as the original single tab back, have seen less use, and will operate the same as my current back.

Please could you explain what you mean by the film being "reversed in its winding as to the set"?

Thanks
Andrew

When you load the film the film does not thread in the same manner as most. It loads so it reverses the roll bend whereas most loads so the film loads with the set. It is because the spools lie behind the plate versus sitting in front or directly beside them. When loaded with the set, the middle of the frame tends to not lie flat while reversed as in the Bronica, the sides of the frame tend to not lie flat. Either way the plate has to have enough pressure to get the frame flat. There are any number of cameras with weak tension and some companies such as Yashica/Contax devised complex systems to make sure the film was flat - look at the Contax RTS III and the vac system it used.

Thanks Brian, that makes sense. I hadn't registered the difference as the ETRSi is my first MF camera.