Archived posting to the Leica Users Group, 2007/10/12
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]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. 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