OK, I have decided to divest myself of my old TLR and 35mm camera and get a bronica. I love the 6x6 format and also love the prices of these things on the used market. My only question concerns the difference between the different SQ models. I have done some research, but really haven't gotten the answers I have been looking for. I know the SQ-AI is newer, but is it better?
16s without bulb, and capability of doing TTL Flash.
If I'm not mistaken, that's all the Ai has over the A, besides that it looks ever so slightly snazzier.
Have both SQ-Ai's and SQ-A's and use them interchangeably. If I were starting over and ran into a good SQ-A with a few good lenses, I'd never look back.
The PS is the later of the two lens series available on the SQ-xx cameras. I believe it's a slight redesign plus better coatings. Some say PS and S lenses aren't much different in the shorter focal lengths, but the PS will be newer. And since the shutter is in the lens, newer should be better. I personally went with an SQ-A and PS lenses (the two - 65mm and 80mm -- that I own thus far).
For me the SQ-A was less money; that was the bulk of my logic. That said, I have had a problem with the first body I bought. That was after about two dozen rolls of film. I have since bought two more bodies at an average of $85. I don't have any ambitions to go to beyond manual exposure with separate light meter, so there's no other compelling features other than likely less age in the SQ-Ai.
The ETRS and ETRSi are similar. The "i" model in this case has the coupled electronic flash with a 4 pronged plug and there is additional coupling with the backs. If the SQA and SQAi differ in the same regard then this is the major difference. It is more than just TTL, it is truly coupled flash with extra features. Sun and Metz both make units for this "i" feature.
Then there is the lens difference. But according to old Bronica literature, the PS and older lenses (S) work on both cameras in the ETRS series.
The PS lenses do have a better coating system. The PS coating system is better for color photography. I shoot mostly B&W with filters, so I don't feel that I need to replace any of my S lenses with PS lenses. I have shot Fuji Velvia color slide film with the S and then the PS lenses, and the PS is a little better, but the S is not bad. I shot same test with the S and PS lenses using Ilford XP-2 B&W film using a yellow filter, and I can not tell any difference. YMMV.
If you are shooting transparency, then PS are better suited. In addition to above reasons, they have half-stop aperture indents whereas the S lenses are only full stop.
For Velvia 50 with reciprocity effect at long exposures anything over than 4s needs you to use B anyway. sequence is 5s, 12s, 25s etc