Archived posting to the Leica Users Group, 2007/10/12
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]The lens is perfect as long as you don't put an IR filter (deep red) on it. I tried color, color desaturated, bw in camera and with other filters, it's fine. Nice contrasty images. On Oct 12, 2007, at 5:39 PM, Steve Barbour wrote: > > 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 > > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information