Nikon F3 Focusing Screen Cleaning?

Has any one had success in cleaning a Nikon F3 focusing screen? If so, what did you do?

It would seem that these older screens slowly draw in more then just dust---outgassing surface contamination, etc. Since the screen is laminated, it concerns me whether dipping it in mild detergent would work, followed by enzyme lens cleaner. Obviously, touching the surface with anything is going to cause damage, so it needs to be solvent based cleaning. A tricky bit.

Does anyone have a success story?

Pete

Pete Myers said:

Has any one had success in cleaning a Nikon F3 focusing screen? If so, what did you do?

It would seem that these older screens slowly draw in more then just dust---outgassing surface contamination, etc. Since the screen is laminated, it concerns me whether dipping it in mild detergent would work, followed by enzyme lens cleaner. Obviously, touching the surface with anything is going to cause damage, so it needs to be solvent based cleaning. A tricky bit.

Does anyone have a success story?

Pete

Click to expand...

Don't dip it!

These screens are a two part assembly. One part is the lens (glass), which sits against the ground glass (appears to be plastic). These two parts are held by what appears as scotch tape (adhesive tape).

For cleaning you need to first remove all screws so the assembly is out of the metal frame, then you carefully remove the adhesive tape so then you can separate the glass lens from the screen.

The glass lens is easy to clean, just glass cleaner.

The screen ("ground glass") itself... you'll have to google. There are people who say you should never attempt to clean it. Honestly, they scratch very easily so proceed at your own risk.

The procedure described above works if what you have is fungus.

If what you have is just dust, then you shouldn't need to separate the glass lens from the ground glass!

So if you dip the whole screen, water could get into the space between the glass and the screen, and then it will not evaporate easily.

Yikes! Having a two part assembly means that one can have four bad surfaces. hee hee hee! Ok, I will make sure not to dip the screen. Thank you for pointing this out. I really do appreciate it. That was one of my fears.

It is easy to give it an air bath and get the dust off, but the slight clouding that seems to occur over the years is difficult. With an FM2n, I can simply replace the screen with a new unit---but not so with the F3. All the used screens have been sitting in a plastic box with foam for years too, and it just seems to lead to a haze on the optics. Frustrating.

It would seem from many web articles that a slight amount of very mild detergent in distilled water would work---but how do you do that when you have a two-part screen? The usual routine is a drop or two of mild detergent in distilled water, then a number of rounds of distilled water rinses, then a photoflo/distilled water rinse. If only a single part focusing screen....

Pete

It is fairly easy to disassemble and clean; if you are careful you can reuse the thin tape used to seal the two screens together. I have some very thin polyester tape that I precut into the 2.5 mm strips to use when I need to replace that tape. I use standard lens cleaner for the first pass and finish with Purosol but you use what you like, the plastic can scratch easy of course so very soft and light cleaning is in order. Living in Hawaii I've often needed to clean these. One key point is when re-assembling to make sure the screen sits precisely into the frame and use the screws and hangers to allow some *light* tension to keep the screen aligned into the frame or else focus errors will occur.

It is encouraging that it can be done, but how do you the existing tape residue cleaned off? Any tricks for it?

Are you using the silver metallic looking polyester tape? It comes in 1/4" wide rolls---I use to use it for mounting negatives to scan on the Hasselblad X1.

And I am glad that I not the only one that had the need to get their focusing screen clean! Thanks for your kind post.

Pete

The tape has no or very little residue so I would not worry about that. I would strongly advise against the silver metallic tape since the it would introduce potential reflections and flare. As far as I know the tape I use looks to be an exact replacement and it is a 3M roll of thin clear polyester tape. I suppose the standard gift wrapping clear tape would work but it has to be thin to allow the set of screens to fit in the frame. Good luck and its pretty easy, using this you can rebuild an F or F2 screen to use the brighter and better Red Dot F3 screens (remember to apply about a 1/3 stop correction to exposure if you use the meter prism).

Pete Myers said:

It is encouraging that it can be done, but how do you the existing tape residue cleaned off? Any tricks for it?

Are you using the silver metallic looking polyester tape? It comes in 1/4" wide rolls---I use to use it for mounting negatives to scan on the Hasselblad X1.

And I am glad that I not the only one that had the need to get their focusing screen clean! Thanks for your kind post.

Pete

Click to expand...

Folks,

No need to overthink it. The tape removes without residue and you can just discard it. It is just there to seal against dust.

The whole dissasembly and cleaning operation is an easy repair.

I am grateful to you both! Thank you for your wisdom on the subject. This is the best of APUG.

I will follow your advise and get it done forthwith. It is comforting to know that others have had the need, and succeeded in the cleaning. You both have shared with me pertinent advise, and I will use it.

Pete

Pete Myers said:

I am grateful to you both! Thank you for your wisdom on the subject. This is the best of APUG.

I will follow your advise and get it done forthwith. It is comforting to know that others have had the need, and succeeded in the cleaning. You both have shared with me pertinent advise, and I will use it.

Pete

Click to expand...

You're welcome. By the way, i agree with RidingWaves -- this is also useful for F and F2 screens.