On Fri, 03 Sep 2010 03:04:15 -0400, rwalker
wrote:

On Thu, 02 Sep 2010 10:50:02 -0700, David Nebenzahl
wrote:

Not true.

Most (almost all?) non-electronic, mostly-mechanical cameras (35mm SLRs)
use "wide-open" viewing, so the aperture doesn't close until the shutter
is released.

I was thinking of my Pentax 67 lenses, which have a separate preview
lever built into the lens.

Just checked the lenses for my old Nikon FG 20. On them, the iris
opens and closes as youi adjust the F-stop without being attached to
the camera.