Mirror or focal plane scratched?

Discussion in '35mm Cameras' started by Nikos, Aug 4, 2003.

  1. Nikos

    Nikos Guest

    Dear all,
    Yesterday when I tried to clean the mirror of my new Canon EOS 10D
    with a plastic air blower, a very thin line appeared on the left
    corner of the viewfinder. I was in a state of panic and I tried to
    clean the thin line with a cloth suitable for lenses. I tried to clean
    both mirror and focal plane when the first line disappeared and
    another line in the same size and almost in the same position
    appeared. It looks like a scratch and I do not know where it is. How
    can I see where the scratch is located (mirror or focal plane).
    With a bare eye there is no scratch on the mirror.
    I took some photos which look like they have not been affected at all.
    What make me wonder with myself is that I was strongly advised NOT to
    touch the mirror :-(. That is why I got the blower. Silly me...
    Thank you very much in advance for your help.
    Nikos, Aug 4, 2003
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  2. Sounds like a hair, got cats?

    Don't worry. The plastic air blower is still your best tool to get rid
    of it. It is likely it moved it around so you could see it in the first

    Don't mess with the mirror or the focal plane shutter. If it were there
    you would not see it anyway. They are also the easiest to damage. (That
    does not mean they are easy to damage, but it can be done.)

    Look above the mirror. That is where the hair is.
    Joseph Meehan, Aug 4, 2003
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  3. Nikos

    Olaf Ulrich Guest

    Never mess around with the mirror! If it has dust or
    scratches on it, just leave it alone!---or have it
    cleaned professionally.

    In the viewfinder? Whatever you can see clear and sharp
    in the viewfinder is located on the bottom side of the
    focusing screen. Stains, dust particles, and scratches on
    the mirror's surface are invisible in the viewfinder.

    Olaf Ulrich, Aug 4, 2003
  4. Nikos

    Nikos Guest

    Yes, I can see the "scratches" clear and sharp in the viewfinder. I
    tried to blow them but nothing happened. I called Canon in Greece and
    they said that they will have a look by the end of this month since
    their staff is on summer vacation. I will not touch it again, not even
    with the blower, until then.
    Do you know whether the focus screen is removable in 10D?
    Thanks for the replies!!
    Nikos, Aug 4, 2003
  5. Nikos

    Olaf Ulrich Guest

    Good idea!

    No, I don't know that. But why don't you just
    ignore it and keep using the camera? Scratches
    in the viewfinder won't show up in the pictures.

    Olaf Ulrich, Aug 4, 2003
  6. Nikos

    Alan Browne Guest

    It's a bit late, but I'll throw in that I have had a 7xi since the early
    90's, which has seen a pile of film through it. Despite continual
    swapping of lenses, etc. there is hardly any dust or anything on the
    mirror. It has never been cleaned.

    I'm not sure why anyone would need to clean the mirror of a 10D...

    It would take a lot of contaminants on the mirror or focus
    screen/prism-box to affect exposure readings. Just leave it alone, and
    if really too much, take it to a camera repair store where they offer
    CLA servicing.

    Alan Browne, Aug 4, 2003
  7. Nikos

    Ken Cashion Guest

    On 4 Aug 2003 00:02:54 -0700, (Nikos) wrote:

    Nikos, I just cleaned up an old camera that had been used for
    several hundred rolls. It dates from about 1982 and the mirror had
    never been cleaned. I have a background in optics and I leave glass
    alone until I know it is degrading the through-put.
    However, on this camera, the mirror cushion/light seal needed
    to be replaced. The mirror had a band of sticky goo at the lower edge
    where it was striking the decomposing old foam light seal.
    I had to remove this old stuff which was close to the bottom
    of the prism and mirror. Then I had to use a solvent to clean the
    lower edge of the mirror. I would not have done this but I didn't
    want it transferring old adhesive onto the new foam light seal
    After I did this, I cleaned everything with air and a brush.
    Brushes are very dangerous in this area because the small bristles can
    reach down in a crack where there could be lubricant and then apply
    that to a mirror or lens where before there was only dust. This smear
    would be a bigger problem than the dust.
    When I got through, I had something on the inside surface of
    the ocular that wasn't there before. It looked like a bad scratch but
    it now appears to be some small part of cement used in the assembly of
    the prism parts.
    What made it go there...in an area where I could not reach?
    I had given it a few puffs of air and swipes with a clean
    brush...and I likely charged some parts of that area and
    static-electricity picked up that little sliver and placed it against
    the lens.
    I could do a lot of things to eliminate it -- and maybe make
    more problems than I want.
    I can ignore it and it will discharge in time (maybe) and fall
    back to where it had been for 21 years.
    It will not make any difference to my pictures. Those are the
    important things.

    Ken Cashion, utilitarian
    Ken Cashion, Aug 4, 2003
  8. Nikos

    Mxsmanic Guest

    It may be a scratch in a coating, which could make it visible only from
    certain angles or rotations.

    In any case, as long as the viewfinder image isn't bad enough to
    interfere with metering (many types of metering systems meter from the
    viewscreen, especially matrix and center-weighted systems), it's only an
    annoyance--it won't affect the finished photographs.
    Mxsmanic, Aug 5, 2003
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