A couple of Bronica SQ-A and lens questions

I just got into medium format photography about two months ago after shooting 35mm for about 14 years with a Bronica SQ-A, an 80mm S lens, and a metered prism. I've been quite happy with the results so far but I've got a couple of questions:

The shutter speed dial on the metered prism appears to override the shutter speed selection on the camera body. I tested that by setting a short exposure time on the body and a longer one on the prism and the longer one prevailed. My question is about the half increment adjustments in shutter speed the prism's dial has which aren't present on the SQ-A camera body. Since the prism appears to override the camera body, does it provide the half step shutter speed increments or should I adjust it in full increments only (i.e. are the half steps only available when used on the SQ-Ai, for example)?

I'm planning to buy PS series lenses for other focal lengths but is the quality difference between the S and PS series great enough that I should consider replacing the 80mm/f2.8 S lens I have now with an 80mm PS?

One last question: is it possible to mount other manufacturers lenses on the SQ-A either directly or with an adaptor?

FWIW, my thoughts . The ps series has a better mc on them, and many were tweaked for the better. If you can find the ps series without paying too much of a premium, go for it. Most of my lenses were of the older type but I am quite happy with them. As for the 80mm, find a 105. I like mine much better than the 80mm

I don't have a metering prism (or a manual for one), so I can't really guess as to the 1/2 stop shutter speeds. If the speed control just sets some resistance value, it's possible the half stops might work, but I've not a clue what the electronic magic in those boxes actually does. The SQ-Ai manual does indicate you lose the Bulb and 16 second shutter speeds with the finder installed, so maybe the finder does take "total control."

I have stuck to PS lenses for my SQ-A, mostly on the theory that they are likely to be slightly newer than the S lenses. That said, as far as I have been able to triangulate from the information I've seen, I don't think there's much difference, PS vs S, in optical quality at the near normal focal lengths. The PS is supposed to have better coatings, and it has half stop detents on the aperture settings. I think the PS had less vignetting on the wide angles, due to a larger front element and filter size.

Rather than the 105, I'd be inclined to get one of the 110 PS macro lenses, since the others don't focus in very close. I have the 110 f/4.5 1:1 macro and it's a sweet piece of metal and glass (as long as you don't have to carry it for hours!)

DaveT

I have that old ME prism which allows you to choose exposure steps in half increments and yes, it really provides half step speeds. if you still have doubts about it check the slower speeds settings, e.g. the half step between 2sec and 4sec or half step between 4sec and 8sec - you'll probably be able to count 3 sec or 6 sec exposure intervals. I use this prism with SQ-A body.

105 S is a beautiful lens and if you're not much inclined towards macro works you'll appreciate it's size and weight against 110/4.5 lens, thus 105 S has minimal focusing distance of 0.8m and is well corrected for close-up shots.

as for S vs. PS, it's been discussed here before and I think the main advantage of PS series overall is half-stop clicks between regular f/values. personally I prefer PS lenses simply because of B switch on PS lenses is much easier to use than screw design on S series. as for coating differences and such you'll have to ask someone else.

The prior PS 110 macro, the f/4, goes to 1:4 without an extension tube. It's considerably smaller and lighter than the 1:1 version, the PS 110mm f/4.5, though the extension tube largely negates the length and weight advantage if used. For close, non macro distances it provides a smaller and lighter package, 1/3 stop faster, taking standard 67mm filters instead of 72mm filters for the f/4.5, and it is cheaper to buy.