[Leica] Which eye(s) do you use?

["Paul Fjelstad" <fjelstad@panix.com>]

This is really basic, about the most basic technique question I can imagine:
Which eye(s) do you employ when you use your M?

For horizontal shots, at least, I tend to keep both eyes open, with my left
eye looking through the viewfinder and my right one essentially blacked out
because it's up against the back of the camera. The other main choices would
seem to be using the right eye and closing the left ... or viewfinding with
the right eye but still keeping the left open, so one eye sees through the
viewfinder and the other sees the same basic scene through mere air.

I see a certain appeal to using this last method, shooting with both eyes
open and watching the shot both through the viewfinder and through the air;
it contributes to the environmentally aware aspects that help make
rangefinder photography different and more "participatory." It does seem to
require some brain adjustments when framing, and especially when focusing,
because each eye is seeing things a bit differently. (Maybe closing the left
eye during focusing is appropriate, for clearer sighting of the split
image?) Of course, the magnification of the viewfinder (.72, .85, whatever)
might also play a role here, in that it affects how different the views of
the two eyes are.

What do you think about this, and what do you do? (Is there a standard I've
been neglecting?)

Paul.