Archived posting to the Leica Users Group, 2008/02/08
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]At 08/02/2008, you wrote: >Hey Nikkor noggins out there: > >Looking at a Nikonos III to throw in the floor of the kayak. Is this >hot spot common with the 35mm lens? > ><http://gallery.leica-users.org/v/ricc/Grab-Bag/hotspot.jpg.html> >http://tinyurl.com/24pjeb > >I got this is a few frames of a test roll. > >Is it light bouncing around between front element and front cover glass? > >Is it avoidable? > >The only other problem I see is a tight rewind crank that is hard to >pull up and push down. > >Thanks for the tips. > >Ric Carter >http://gallery.leica-users.org/v/ricc/ Hi Ric! There's been a recent discussion over on the LRflex list, about this very problem... I was getting it with my 80~200/4 Vario on various digital bodies. Apparently, when conditions are just right (very rare), light will bounce off the sensor, back to the rear element of the lens. If the curvature of that rear element is just right, that light will be bounced back, once more, to the sensor, making a blue (colour of the coating) dot/smudge/smear, dead center, in a size which varies with the aperture. The problem is apparently known with various lenses from many different makers. In my case, though I can recreate the problem under controlled conditions, in the wild, it has affected fewer than a half dozen shots, in more than 10,000. That being said, to my knowledge, this has only occurred with digital sensors, as the matte finish of film does not reflect significantly. And, last I heard, the Nikonos was film based only. Your theory of the front element and cover glass may be correct. Weird! Silicone lubricant spray may help the rewind knob. Good luck! --- David Young, Logan Lake, CANADA Limited Edition Prints at: www.furnfeather.net Personal Web-site at: www.main.furnfeather.net Stock Photography at: http://tinyurl.com/2amll4