Matthew Schaefer , Feb 04, 2012; 06:05 p.m.
I bought a used Zeiss 150mm Sonnar lens recently. It results in good photographs in most situations with no noticeable defects. But when I shoot into the sun it results in a strange effect. It's not quite a flare, but rather a "frosting". Stranger still is that the frosting is unmistakably missing from the top of the photo. The frost starts about 5mm from the top of the negative. I've repeated this effect several times so this photo is no fluke.
Can any one explain why this occurs? Is it a known issue?
Thanks,
Matthew
Question about frosting from sun
Rob F. 
, Feb 04, 2012; 06:37 p.m.
I see your point. If we had any sun today, I'd go out with my 150 Sonnar and try this out. I never tried shooting into the sun with it. I'm thinking there could be a reflection inside the camera chamber. See anything shiny in there? Or in the lens?
Marco Venturini Autieri , Feb 04, 2012; 07:10 p.m.
If the top of the photo is missing the flare, then it is not flare. Light leak perhaps?
Greg Jones , Feb 04, 2012; 08:18 p.m.
Looks like a typical Hasselblad film back light leak. You need to replace the light trap seal. Not a hard thing to do if you are halfway handy. First, call Hasselblad and order the light trap kit. Less than $20, as I recall. Then get a set of small screwdrivers, like at Radio Shack, and unscrew the face plate on the film back. Note how the light trap foil piece goes in. Remove it, and replace with new. Replace face plate and screws, voila no light leaks.
This is a normal occurence for a Hasselblad film back, especially one that has been stored for a long time with the slide in it. The light seal gets compressed, and loses its "springiness" and you get light leaks.
Q.G. de Bakker 
, Feb 04, 2012; 08:24 p.m.
Here's my 'text book example' of flare once again, also a 150 mm Sonnar shot:
Note, Marco, how the flare starts a fair distance from the side (not the top, but that's a matter of where the sun was). Yet i'm 99.999% sure it is flare, and not a light leak.
I concur with Rob that it could be a reflection off something inside the camera. But i'm not sure. I also think possible that it happens inside the lens.
Michael Axel 
, Feb 05, 2012; 12:09 a.m.
I've seen this before, and was quite certain it has been discussed on pnet before. I think we believed it was a design issue with the camera.
Jim Momary , Feb 05, 2012; 01:20 a.m.
Matthew Schaefer , Feb 05, 2012; 02:41 a.m.
Thanks for the responses. I had a light trap leak and just recently replaced the the foam seal. That leak was much different - more random and streaky and coming from the side. I haven't had any flight leaks or this flare issue while shooting with my Zeiss 80mm/2.8. It just started with my 150mm, so I would agree with Q.G. de Bakker that this is caused by the lens, especially since others are reporting a similar effect.
Ingemar Lampa , Feb 05, 2012; 04:03 a.m.
T* or not? Any UV or other filter? Because it is on the RH side of the frame it may be a bad seal since the neg is inverted compared to the picture and the leak would be bottom left in that case. Or it is indeed a flare. My 250 Sonnar non-T* flares very easily if I'm not careful and also use the shade at all times.
Q.G. de Bakker , Feb 05, 2012; 06:40 a.m.
I'm sure it's not a light leak.
It's also not a coating issue (my example was produced using a nicely T* coated Sonnar).
Could it be avoided with another, longer lens hood? I don't know, but believe not. It happens, it would appear, when the source of light is just outside the field of view. A 'borderline' thing, leaving little room for a longer shade.
I'm also thinking it's a 150 mm Sonnar specific thing, because i don't think i have ever seen it when another lens was used.
My example was produced using a CF version of the 150 mm Sonnar. What version is your 150 mm Sonnar, Matthew?
