Archived posting to the Leica Users Group, 2007/10/12
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]On Oct 12, 2007, at 2:35 PM, Leonard Taupier wrote: > Steve, > > So far that's two for two. (George's and my son's). I had to borrow > my sons as I only have the Elmarit. It would be interesting to know > how the new Elmarit asph fares. how is the effect manifested in bw images? Steve > > Len > > > On Oct 12, 2007, at 5:11 PM, Steve Barbour wrote: > >> >> On Oct 12, 2007, at 2:10 PM, Leonard Taupier wrote: >> >>> George, et al. >>> >>> I've verified a problem with the >> >> (or my) ?? >> >> >> ....tested one sample, or multiple cron 28's....? >> >> >> >>> 28mm Summicron on an M8 and IR filter when trying to take Infra >>> Red photos. >>> >>> There is a hot spot present in the center of the frame when >>> trying to take IR photos with the above setup. The problem looks >>> like flare, a circle of low contrast in the center of the frame. >>> The problem is most noticeable at the smaller lens openings where >>> the hot spot is clearly defined. As the lens is opened up the hot >>> spot becomes larger and less pronounced but the center area is >>> still lower contrast. I did not see this at f2 and f2.8. Here is >>> a photo taken at f16. >>> >>> <http://gallery.leica-users.org/v/LeonardT/Infra_Red/ >>> 28mmSummicronIR.jpg.html> >>> or >>> http://tinyurl.com/yreo78 >>> >>> I used two M8 cameras for the test. All photos were taken on a >>> tripod with the sun directly behind the camera and shaded by my >>> body. The filter was a Hoya R72. A lens hood was on the lens. The >>> problem showed up with both M8 cameras. >>> >>> The same test was also performed using the 28mm f2.8 Elmarit (non- >>> asph), 35mm Summicron asph, 24mm Elmarit asph and the 21mm >>> Elmarit asph. Only the 28mm Summicron asph showed the hot spot >>> problem. >>> >>> The problem does not show up when using a Red R60 filter. >>> >>> Len >>> >>> >>> >>> >>> >>> >>> _______________________________________________ >>> Leica Users Group. >>> See http://leica-users.org/mailman/listinfo/lug for more information >> >> >> _______________________________________________ >> Leica Users Group. >> See http://leica-users.org/mailman/listinfo/lug for more information > > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information