The OP has not really explained why he wants this combination, but some of the suggestions aren't going to help much. For basic "macro" work, I indeed use the Zenzanon PS 110 mm f/4.5 1:1 which is a really sweet piece of glass. The Bronica extension tubes typically come into play to focus a bit closer, as most of the bare lenses can't focus closer than about 1 yard/1 meter, some not even that close (true of many medium format families I believe). Temporarily improvising would be pretty tough for the SQ series -- the shutter is a leaf type in the lens driven by mechanical linkage and timed by electronics in the camera body. That would be mighty difficult to improvise -- and likely also explains why the extension tubes sell for non-trivial sums -- which is why I don't own one! I guess a secondary question is would a +1 closeup lens work better than an extension -- although the 40mm likely can't handle anything stuck on the front. I have a 50mm and any attempt at using a lens hood is tedious.