Archived posting to the Leica Users Group, 2001/11/15
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]John, I don't know, maybe it's "normal," but it don't seem right. 1.4 is 1.4, or should be. Seems to me what you're saying is that the Summilux is really only a 1.5 or 1.6 lens because of vignetting, and the Noctilux only a 1.1 or 1.2, no? Unless the optical system somehow affects the meter differently than it does the actual exposure on film. What am I missing here? I don't pretend to know the answer; I'm just asking questions. :-) Arthur G. Peterson Alexandria, Virginia - -----Original Message----- From: John Collier [mailto:jbcollier@powersurfr.com] Sent: Thursday, November 15, 2001 9:50 AM To: leica-users@mejac.palo-alto.ca.us Subject: Re: [Leica] Responsiveness of M6 meter at f/1.4 to f/2 It is normal. The inherent vignetting of any optical system wide open causes this effect. It is most noticeable with the Noctilux. See Osterloh's Leica M book for a well illustrated explanation. John Collier PS: Try your local library for the book. I might be persuaded to scan the relevant sections out of my copy if you cannot locate it. > From: Ray Moth <ray_moth@yahoo.com> > > I've just noticed a peculiarity in the behaviour of the light meter in > my M6 TTL, using a 50mm Summilux-M lens. If I adjust the aperture from > f/1.4 to f/2 or vice versa, the meter doesn't register any change, > whereas a change in shutter speed does register. > > For example, if the meter indicates that f/1.4 at 1/500 sec. will give > the correct exposure, then I would expect f/2 at 1/250 sec. would give > the same indication but it doesn't; it shows over-exposure, as if I'd > selected the slower shutter speed but left the lens aperture at f/1.4. > Conversely, if I started at f/2 and 1/250, a change to f/1.4 and 1/500 > would indicate an under-exposure. The lens aperture selector seems to > function properly. Has anyone else experienced this problem? - -- To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html