How to Clean a Nikon F Viewfinder Screen?

Discussion in 'Camera Building, Repairs & Modification' started by Ralph Javins, Aug 20, 2010.

  1. Ralph Javins

    Ralph Javins Member

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    Good morning;

    A Nikon F and F2 Type "R" viewfinder focusing screen has arrived. It looks like it needs to be cleaned. What is the safest and yet effective way to clean a Nikon viewfinder screen?
     
  2. bdial

    bdial Subscriber

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    A camel's hair brush has always worked well for me. If there is dust inside it, you can take it apart by removing the four screws.
     
  3. 2F/2F

    2F/2F Member

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    Is it just dusty, as in loose material, or is it actually dirty, as in needs to be moistened to get rid of the offending material?
     
  4. Ralph Javins

    Ralph Javins Member

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    Good morning, gentlemen;

    Thank you for the comments, and, yes, as you have indicated, I did not really specify the degree of cleaning necessary, did I?

    I wish this were just a dust problem.

    The bottom of the screen, the fresnel lens portion of the screen, along with the top part, seems to be coated with some kind of a light brown or tan colored thin layer of something. It has a mottled appearance. I think this will be some sort of a washing procedure. I do know that there are certain precautions to take when attempting something like this. Some of the early Canon screens are very sensitive about alcohol; they will turn a milky white. I am not sure about any similar precautions to be observed with Nikon screens.

    I do have a couple of ultrasonic baths (up to 2 quarts in size) that could be used, if that is a safe way to go. I just do not know about any thing to avoid with a Nikon screen, such as the alcohol problem with the early Canon screens.
     
  5. Ken Nadvornick

    Ken Nadvornick Subscriber

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    As luck would have it, I just recently finished successfully cleaning a rather dirty Nikon F/F2 Type "R" viewfinder focusing screen for my F2 body. Here's what I did:

    First I disassembled the screen by removing the four retention screws on the frame. The screen was extracted and examined. Turns out that this particular screen type (or at least my sample) is a two-part sandwich held together by a very thin strip of transparent plastic attached to the screen edges by an adhesive. One half is the clear lens. The other half is the fresnel screen containing the rangefinder. My presumption is that the adhesive strip was used as a barrier to prevent dust from entering between the sandwich pieces.

    I pulled off the transparent strip and the two halves fell separate. I then filled a small ultrasonic cleaning unit with 99% isopropyl alcohol (not the watered-down "rubbing" isopropyl alcohol). I placed each individual half separately into the ultrasonic bath for 10 minutes.

    When complete I then placed each half into a small container of distilled water as a final rinse. I then air-dried each piece using a can of Dust-Off and reexamined them. After the first cycle the ridges of the fresnel lens were clean, but the raised portions making up the central small circular rangefinder patch still had some crud adhering, so I repeated the cycle for that piece. After the second cycle it too was clean.

    I reassembled the screen without using any type of adhesive tape, either new or the original, which I discarded. The frame alone holds the two pieces together in perfect register without the need for any tape, which is why I'm assuming it was simply a dust barrier.

    The screen is now clean and bright and works perfectly. There is no evidence of any harm from using either the ultrasonic unit or near-pure isopropyl alcohol. There is no visible milkiness or other signs of damage to the screen optics.

    However, I would caution against cleaning the black metal frame in the same way, as I have in the past tried that and had the misfortune of removing both the painted-on Nikon logo as well as the screen type designation letter.

    Hope this helps.

    Ken