Steve Desjardins wrote: > > Stupid question. I've read that an M lens on the *ist will only meter > wide open. If the camera can't talk to the lens, how does it know what > wide open is? and if its reading the light coming through the lens, why > won't stopping down affect metering? Probably an obvious answer, but I > can't see it.
With an M lens there's no digital data being sent from the lens to the camera (obviously) so the camera doesn't "know" what wide open is, it just meters whatever light is coming through the lens to the focusing screen. With standard M and K lenses, this is wide open, because the aperture lever is holding the lens diaphragm open. (With stop-down lenses like the 28mm shift, it's the aperture to which the lens is actually set.) -- Mark Roberts Photography and writing www.robertstech.com
