Is this fungus?

Hello all.

I'd like to ask you all if you know anything about 'fungus' or 'mould' in cameras?

I've noticed a dark patch in the viewfinder of my 'new' zorki 4k which goes across from the top right, along the top of the frame to about the middle of the viewfinder, with the top edge being almost straight, and the bottom edge being wider at the right-hand side and narrowing almost to a point in the middle of the 'finder. I was holding it almost at arms length to try and get an 'in focus' view and I saw that this 'patch' seems to carry on nearly all the way across but seems to be pale green from the middle of the 'finder, and gets progressively paler to almost 'is it still there on the left side?'

All this is very slightly below the line of the 'finder, giving a space above the patch, and doesn't really go below about 1/4 down on the right.

It is quite hard to see with the eye at the 'finder window, and it is quite high up, so I didn't really see it before as I was looking at the rangefinder (which gives an image that is slightly below the real image).

It seems odd to me that fungus/mould would have an almost a straight line along the top of it.

Does this seem like it may be fungus to anyone, and do you think it could be fixed?

Any help would be much appreciated.

Would I be able to make it easier to see the whole viewfinder frame by removing the black plastic around the eyepiece, filing off the vertical and horizontal 'frame' and then replacing it, or is this a mad idea?

Hard to say without a picture - and it would no doubt be impossible to photograph - but it does not sound at all like fungus. Fungus normally looks like cobwebs, or the tributaries of a river, or sometimes an irregular blob.

If you feel like taking the top off to investigate further you'll find instructions [url="http://www.rangefinderforum.com/forums/showthread.php?t=33914"]here[/url].

Thanks for the reply and link Moriarty. I'd be far too chicken to have a go myself - I have few tools and almost no skill.

I described the problem in an email to a member of staff at "The Real Camera Company" in Manchester, which I go to sometimes. They are a well-established shop which deals with second-hand cameras, from old Leicas all the way through to large format. They even had an Alpa camera, but it was too high for me to tell if it was an 11si.

The staff member(Chris) says it seems likely to be silvering deterioration to the rangfinder mirrors, and replacement would be necassary. This would be expensive and exceed the value of the camera.

It's a shame as the rest of the camera, apart from the rangefinder giving an image very slightly below the real image, is in near mint condition. The lens is in even better condition.