Hello Ralph,
thanks for your reply, that's an interesting discussion. I'm not at home at the moment, so I have to write it by memory, too. Let's see:
"In reference to the Minolta SR-1b, that is the designation that was on the box, the warranty card, and in the owner's manual..."
That's new to me, I never have seen this. I own manuals of each type of SR-1, and the only appendix I have seen, is the "Model V" designation. Too bad you haven't any pictures of that.
"...there were two sub-variants in the way that they worked, which included the addition of the improved lens diaphragm automatic stop-down and reopen, and then the reflex mirror auto-return after taking the photograph, and no longer required advancing the film to reposition the mirror for viewing through the lens."
Okay, you're right with the first statement regarding the diaphragm operation, but all Minolta SLRs beginning with the SR-2 had instant return mirrors. So if you have a SR-1 with a mirror, that returns only by operating the film advance lever, it's simply a mechanical failure.
So I just tell you my actual classification. I denote the several types with an appendix like SR-1.3 for 3rd type, model, generation, edition or whatever you wanna call it. I also note the order no. given in the service and part's manuals. None of these notations appear on any camera, manual, box. I just list the differences to the previous model.
SR-1.1
July 1959, model SR
semi auto diaphragm (re-opens when operating film advance lever)
aperture lever with long travel
lift-to-turn shutter speed dial
LV marks
instant return mirror
round frame counter window on the left
serial on the left
SR-1 on the right with green color
engraved with CHIYODA KOGAKU right side on the top
ASA/DIN scale split for color and b/w
lens: 55/2, LV, aperture lock, uneven F stop scale, half stops, long travel aperture lever
SR-1.2
August 1960, model SB (released with SR-3.1)
clicking shutter speed dial
SR-1.3
April 1961, model SD
fully auto diaphragm (re-opens instantly after exposure)
lens: 55/2, LV, pre-view lever, even F stop scale, no half stops, short travel aperture lever
SR-1.4 (what you call SR-1a)
August 1961, model SD' (released with SR-3.2)
rounded meter shoe on the right (for the clumpsy Selenium meter)
SR-1 on the left, still green
lens: 55/1.8, LV, pre-view lever, even F stop scale, no half stops, short travel aperture lever
SR-1.5 (what you call SR-1b)
July 1962, model SF (referred as New SR-1, released with SR-7.1)
new lighter and more square shaped body
square meter shoe on the right (for slimmer CdS meter 2)
aperture lever with short travel
no LV marks
square frame counter window on the right
serial on the back, right of view finder
SR-1 on the left, now black
engraved with CHIYODA KOGAKU left side on the top
lens: 55/1.8, no LV
In July 1962 Chiyoda Kogaku Seiko, K.K. changed its name to Minolta Camera Corporation, LTD., but the first batch of about 30.000 cameras was still engraved with the old brand name.
SR-1.6
late 1962, model SF
engraved with MINOLTA CAMERA CO., LTD. left side on the top
new ASA/DIN scales concentric
SR-1.7
September 1964, model SF-B
new styling of film advance and self timer levers
That's it. Further, we have two models of SR-1 (V) and two models of SR-1s, so all in all we count 11 models of SR-1. I'm going to set up a web site on this in the next time, including many pictures and serials and production numbers.
BTW my most recent purchase in this field was a SR-1.3 (the rarest model of all) with matching lens and manual. Interestingly the manual is the one of the SR-1.2 with a inlaying leaflet, that describes the changes to fully auto diaphragm and the new lens generation. Excellent finding!
Best regards,
Dennis.