Archived posting to the Leica Users Group, 2004/01/08
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]- ----- Original Message ----- From: "Don Dory" <dorysrus@mindspring.com> > John, > Thanks for the link. I guess for rangefinder users that just about > settles the question for 1A or UV filters unless there is a specific > need like saltwater, sand, two year olds with peanut butter It does, Don, if there is a light source in or near the viewing angle as is obvious in three of the four images. And depending on the aperture. Otherwise, I am not persuaded. Recently while testing a dual-range Summicron (yeah, yeah, you know me!) on an EROS MTF apparatus, just after running the MTF curves at f/5,6 and 12mm off-axis (the height of the near edge), out of curiosity I put on a Leitz E39 UV filter. I did it off-axis because on-axis, the light beam is of course directly through the center of the lens and much less likely to flare or degrade the image. The curves without and with filter were absolutely identical. If there were not a ruling from on high - and a correct one - that one cannot attach files to a LUG post, I would show you the curves. Incidentally, the contrast of the dual-range at f/5,6 at the critical (according to E.P.) 20 and 40 lp/mm is at least as good as that of the current 50/2 Summicron whose official MTF curves I have inspected. That said, I would still not use a UV filter in available light conditions nor outdoors unless physical damage were a risk, Don's mentioned saltwater, sand, 2 yearolds etc. P.S. at 2150 here in the foothills of the Aridondacks (sic) the thermometer temperature is a springlike -20 C. and almost everything is white. Seth LaK 9 - -- To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html