Mamiya shutter speeds

I've got a Mamiya 645 Pro, with a standard 80mm lens. It also has the power-winding handle which fires the shutter and advances the film, moves the mirror, makes coffee ooops, delete that last one... Anyway, how low of a shutter speed could I handhold before I get significant blur? The reciprocal of the lens focal length??? To go lower could I use the usual dodges (brace in a doorway, use a bag, etc.)? I really like to use it without a tripod, since I own a Bogen Variable Weight model (the farther you carry it the more it weighs....)

Thanks to all who reply.

With best regards.

Steve

I've been shooting mine at 1/60th with the power winder and no tripod with good results. I'm sure you could do it even slower than that.

"Bogen Variable Weight model" ha ha, have several of those myself.

Ones ability to hand hold varies between different people and age.

Without bracing, I would estimate 1/30th would be doing good, not everyone will be able to do that, some may do better.

Reciprocal of focal length was always quoted as min. handholdable speed in 35mm. format. Angle of view is the thing to bear in mind though, and of course people's abilities vary.
One trick I always liked is a string/tape/cord/wire attached to a strong point on the camera. I usually used a tripod mount screw but for longer lenses the further forward the better.
The "string" is long enough that you can stand on the other end to tension it or make a big loop and stand on the middle while holding & adjusting the other end. It's about as good as a monopod I guess - never owned one of those though.
It's worth getting into the habit of checking the end for any unpleasantness before putting it back in your pocket...
One of those retractable dog leads might be worth trying.