Archived posting to the Leica Users Group, 2001/02/28
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Dear Puzzled, The fault, dear Brutus, is not in ourselves, but in the stars. That is, I think the problem is nor your lack of perspicacity, but rather M. Gilchrest's understanding of the universe. IOW, I think he's wrong. Camera shake as I understand it has to do entirely with the angle of the scene that is swept by the lens while you're shaking it, multiplied by the magnification of the lens. I'd expect two 21's if different designs but the same weight to exhibit the same camera shake charactertistics when mounted on the same body. It sounds like DG is thinking of the light path in some sort of lever-like terms, with the principal plane acting as some sort of fulcrum. Kind of an odd view of optics... Paul - -----Original Message----- From: John Collier [mailto:jbcollier@home.com] Sent: Wednesday, February 28, 2001 10:21 AM To: leica-users@mejac.palo-alto.ca.us Subject: [Leica] Puzzled in Alberta would like to know.... I have been reading the LHSA archives and came across a curious statement by Dick Gilcreast in his article on the 21/3.4 and 21/4 lenses: http://www.lhsa.org/angulons.htm Here is the quote I am puzzling over but please read the whole article to get everything in context: "The 21mm f/3.4 Super-Angulon is very sharp and relatively reflection free at all apertures. And, unlike a retrofocus design, it can be handheld at quite long shutter speeds because of the very short distance between its principal plane (where the diaphragm is located) and the film." Now why would there be a difference in the effects of camera shake between symmetrical and retrofocus designs of the same focal length? It does not make sense to me but that is hardly surprising as I was repeatedly dropped on my head in my youth and thus am unable to understand the simplest of concepts (such as the point of the UV filter thread for instance). Please shed some light into the great void that is my brain. Cheers, Puzzled in Alberta