May I ask... when using it handheld with a 135mm lens, what shutter speed must you set to obtain sharp images?
I've been out recently playing with a Crown Graphic with the 135mm Optar. The shutter is, as usual, slow on the high and low ends. I'll get it serviced at some point, but until then I measured the "effective" speed when set to 1/400 as really 1/202. If I use a cable release (not the body release) and hold reasonably still the negatives look reasonably sharp. (HP5+ at EI400, 1/202 at f/22 on sunny days gives gorgeous negatives.)
I'm curious regarding your, and any other's, handheld protocols to minimize camera shake.