Nikon F100 Focusing Screen Problem

Discussion in 'Nikon' started by rick_gray, Feb 15, 2009.

  1. I have a problem with my loyal and very dear, ten year old Nikon F100. When I look through the viewfinder, all I see is a round black circle that appears to have the top one sixth sliced off. When I look more closely, it's as if a curtain has dropped down slightly over the entire screen. Also when viewed against bright light, the circle appears to be surrounded by a black shroud with faint pin lights. Also faint light can be seen around the square frame of the viewfinder. I am six hours by car from the nearest Nikon service. Any guidance would be most appreciated. Ten thousand thank yous in advance.
  2. Do you have a viewfinder eyepiece blind partially closed? Look for a lever in the eyepiece area..
  3. There are no moving parts inside the viewfinder to fail. Does the camera fire when you push the shutter button? Batteries OK (mirror not locked up)? Have you opened up the camera and checked the mirror and the VF screen? Are both OK and in the right position? The F100 doeasn't have an eyepiece blind, so there is only the eyepiece glass, pentaprism, screen and mirror in the optical path. The screen holder might have popped open and dropped down into the mirror box.
  4. ShunCheung

    ShunCheung Administrator

    As Rick points out, check the position for the mirror. If the mirror does not quite rebound back to the normal position, it'll affect the image on the focusing screen. Remove the lens, and while looking into the viewfinder, gently move the mirror with a finger and observe how the image changes.
    The F100 indeed does not have a prism eye-piece curtain. That is a feature reserved for the top-of-the-line Nikon DSLRs such as the single-digit F series and D series (and the D700).
  5. Thanks Ronald and Rick for getting back so promptly. Yes the camera fires fine; yes batteries are good and the mirror is not locked up. However I just found the E-type Fresnel focusing screen (grid pattern) that has fallen out. Rick, is this what you are referring to? This must be the problem. How do I reinsert it? Could a standard camera technician do this with tweezers? I'm not confident to do it myself. Mucho thanks.
  6. ShunCheung

    ShunCheung Administrator

    The F100's focusing screen is user replacable. It is supported by a frame that is hinged in the back and drops down so that you can replace the screen yourelf. Just make sure that the screen is fitted into the frame and gently push the the front of the frame back up so that it clicks in place. Most Nikon film SLR bodies in the AI era such as the FM/FE series use this style of user replacable screen mechanism (except for the likes of F3, F4 and F5 where you remove the prism to change the screen).
    I just updated the thread subject to reflect the actual problem.
  7. Yes, that is what I was referring to. It is easy to put back in yourself, and users regularly change screens. If the screen fell out, that means the metal frame that holds it in is already open. just place the sceen in the frame with the tab facing you - it only fits one way so you can't get it backward. Make sure the screen is free of dust before dropping it in. Then gently push up on the front edge of the metal frame with a small tool like tweezers or even a q-tip until it clicks firmly in place. Don't push on the screen, only the springloaded frame. You can find more detailed instructions googling around. If you really are not comfortable doing this yourself, any camera repair tech can fix it for you in 30 seconds.
  8. Rick and Shun, it is exactly what you said. I have reset it with ease in a few seconds. Done and dusted. My F100 is reborn and loaded with Tri-X. You folks here at PN are just amazing. Again one thousand thank yous.
  9. ShunCheung

    ShunCheung Administrator

    Hi Rick Gray, after you push the screen back in place, just do a quick check focusing to infinity and make sure that when you see infinity is sharp in the viewfinder, the lens also shows infinity. Pushing that frame back in place is a bit tricky. If it is not firmly in place or just a bit off, your manual focusing can be way off. I had that same problem with my FE and FE2 years ago.
  10. If I have a little ant after the condensing lens (the screen after the focusing screen) how can I remove it? I buy from ebay a F100, used and I take out the focusing screen and I see it inside (after) that screen. Can I remove some how the this screen?
    Thank you so much.

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