I think I've just found my lens for May.
SMC-M 135mm f/3.5; it was set to either f/5.6 or f/8. Flash was a straight AF200Sa thyristor unit; oddly enough the recommended f-stop per the flash instructions seemed to have been too powerful by a short margin (too close?).
Unbounced light might be "direct and unflattering", but here it seems to do the subject justice and the detail is pretty good for this oldster. And it's (relatively) small and light like all the M lenses and a lovely, smooth-focusing example; the handling on the K-1 is nothing short of exquisite.