Nikon F desilvering prism. What to look for

[megido]

I have just received my first F. On looking through the plain prism viewfinder I noticed a series of curved lines somewhat resembling grooves on a record. They appear in the top and bottom left corners. There are also some small black spots across the very top of the screen too. Having no experience with desilvering prisms, would you say this is the case?
Thank you
M

 

[Mackinaw]

What kind of focusing screen do you have? You may be seeing the fresnel pattern on the screen.

Jim B.

 

[megido]

Focusing screen type A

 

[Huss]

Post an image. U can use your smartphone to take a snap. It could be 'just' the focus screen.

 

[megido]

Huss
I have tried to post photos in the past with no joy. I've made many enquiries on how to do but still no joy for this luddite.

 

[Peter Jennings]

Take the prism off the camera and then look through it. You can easily see if it's desilvering this way.

 

[Contarama]

See Richard Haw's site...he has a pretty good write up on it although black electrical tape really??? Surely there is something better.

 

[Contarama]

Huss
I have tried to post photos in the past with no joy. I've made many enquiries on how to do but still no joy for this luddite.

You have flickr?

 

[megido]

Take the prism off the camera and then look through it. You can easily see if it's desilvering this way.

I removed the prism and it certainly looks clear. So it must be the screen, which I intend to change anyway. Thank you for your help.

 

[megido]

The only other potential problem is that the back door seems a little loose. It makes a soft clicking noise when handled in situ. A loose latch maybe? The door itself doesn't look warped to the eye.

 

[Peter Jennings]

The only other potential problem is that the back door seems a little loose. It makes a soft clicking noise when handled in situ. A loose latch maybe? The door itself doesn't look warped to the eye.

Banged-up backs on user cameras can sometimes make noises during handling. It's not a problem as long as the camera is still light-tight.

 

[megido]

Banged-up backs on user cameras can sometimes make noises during handling. It's not a problem as long as the camera is still light-tight.

The back doesn't look damaged at all, could there be an easy fix such as tightening the latch for example?

 

[Peter Jennings]

It's hard to say without seeing the camera. Examine it very closely and try to deduce the source of the sound. If it's coming from the base, then it could be a loose latch. If it's coming from around the edges of the camera where the back and body join, it could be the back is slightly warped or bent. You just need to investigate closely. And if the camera is light-tight, don't worry too much about it.

 

[Robert Lai]

With the prism off the camera, and looking from the focusing screen side, you can see desilvering as irrgular brown spots.

Unless you know that the old foam is removed from the pentaprism, desilvering will eventually happen.

The spots you are seeing, if small may be degenerated foam particles from the mirror stop, which has landed on the focusing screen. Remove the focusing screen, and try blowing them off with canned air. In this case, you need to get the camera refoamed.

Sover Wong is the only person whom I know does a thorough job on removing all the old foam, and replacing with new.

 

[Timmyjoe]

One of my F cameras came with a loose back door. It did what you're describing when handled, moved around a bit, made clicking noises as it shifted slightly on the camera. Was the far latch on mine, a metal piece on the end of the door away from where the lock "knob is. From years of use it had gotten bent slightly "up" and wasn't holding tightly on the protrusion from the camera it is supposed to grip to. Not saying that's your situation, but might be something to look at.

Best,
-Tim

 

[megido]

One of my F cameras came with a loose back door. It did what you're describing when handled, moved around a bit, made clicking noises as it shifted slightly on the camera. Was the far latch on mine, a metal piece on the end of the door away from where the lock "knob is. From years of use it had gotten bent slightly "up" and wasn't holding tightly on the protrusion from the camera it is supposed to grip to. Not saying that's your situation, but might be something to look at.

Best,
-Tim

This sounds exactly what my door is doing.. I'm going to take a closer look. How did you fix the problem?

 

[megido]

You have flickr?

Apologies for missing your post. Yes, I have flickr.

 

[megido]

So...i changed out the screen and the prism yet the black spots still remain. At this point i'm curious rather than anxious! Any ideas where these spots could be situated?

 

[tunalegs]

Have you done the simple thing? Remove the prism. Hold it in your hand. Look through it. Aim the screen side of the prism at something light colored (like a white wall or the ceiling). Do you still see the spots? If so, the problem is with the prism. If not, the spots are probably on the focus screen.

 

[megido]

Have you done the simple thing? Remove the prism. Hold it in your hand. Look through it. Aim the screen side of the prism at something light colored (like a white wall or the ceiling). Do you still see the spots? If so, the problem is with the prism. If not, the spots are probably on the focus screen.

Yes, i have tried that. See earlier post ;-)