OK, this has nothing to do with how close a specific lens will focus, it's how close the body will couple the lens to the rangefinder. A modern 50mm summicron focusses to .7 meters, put that lens on an early M3 that hasn't been modified and, while of course the lens will still focus to .7, the rangefinder will stop moving, decouple, as you focus in past 1 meter. So focusing closer than 1 meter using the rangefinder will give incorrect focus.
So, to restate, if you take a modern Voigtlander lens that focus to .7, .8, or .9 meters will the rangefinder be able to focus the full range of the lens?
To test this you place the lens on the body and turn the focus all the way in to the nearest focus point. Now focus on something close by moving THE WHOLE CAMERA until something comes into focus in the rangefinder. Now rotate the focus on the lens out in the direction of infinity. If the rangefinder image moves immediately as you rotate the focus barrel, than you are fully coupled. If you don't see the rangefinder image move until you turn to, say, 1 meter, than that is the closest point that the rangefinder is able to couple with the lens.
It always surprises me how many people with M3's don't know that their camera can't focus the modern lenses up close. It's a simple fix on an M3, but it's just not within the design of some cameras to focus closer, such as Leica iii's (I believe).
