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 2:10 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