I have a quick question. I have a SQ-Ai. Can I use a SQ back or do I need to use an SQ-I? I'm thinking all I'll loose if I use an SQ is the info for metering. Is that correct? Since I'm using a waist level finder I really don't need the info or is there something else I don't know about? Thanks!
All the SQ backs with the exception possibly of an SQB back will have the metering contacts. Just be sure the back you get has good seals and advances properly.
Are they are the two small copper/gold coloured posts sticking up... (I have an SQ-A) - if not, what do they look like?
From the Tamron site:
While the backs between the previous models and the SQAi are fully compatible, the newer backs were modified slightly at this time. The ISO dial was relocated to the rear of the back, rather than on the top, so that the speed setting could be seen better with a prism attached. The ISO range was also extended to 6400.
Thats right! If you really are picky you should test each back for metering accuracy, as each one becomes part of the metering system. Each one has its set of contacts with its resistors to modify the EI reading for where its set. Inherent in this would be small variations in manufacture or wear that could introduce some inaccuracies here and there.