I find it hard to believe that a gentle wiping of the mirror can knock
it out of alignment when the mechanical lifting and dropping of it does
not affect it. The second seems much more severe than the first. I
agree that you don't see particles on the mirror and they don't affect
the viewfinder image, but on the *istD I'm concerned that they'll end
up on the senosr. How do others here feel about cleaning mirrors? I may
decide to abandon this practice if the consensus is a clear "no."
On Nov 22, 2004, at 9:53 PM, William Robb wrote:
----- Original Message ----- From: "Paul Stenquist"
Subject: Re: cleaning focusing screen / pentaprism
I have cleaned mirrors with lens cleaning fluid and a microfiber
cloth when necessary. (I cleaned the mirror in my *ist D last week.)
I apply only very gentle pressure and avoid unnecessary contact. I've
never seen any negative effect.
My concern with touching the mirror has nothing to do with the surface
of the mirror.
Fer Gods sake, its metal!!
Surely not the hardest metal around, but still, it's metal.
My concern is that repeated cleaning can, over time, knock the damned
thing out of alignment.
If there's a little dust on the mirror, so what? The only time you can
see it is when you take the lens off. It sure isn't visible in the
viewfinder.
Knock the mirror out of alignment, and all of a sudden you are yipping
about those crappy Pentax lenses, and how you don't ever seem to get
sharp pictures.
If I absolutely have to clean a mirror, and let me tell you, it's not
something I approach doing without a lot of trepadition, this is what
I do:
1) Take off the lens.
2) Put a drop of optical glass cleaner on a Q-Tip.
3) I reach into the camera body with my little finger (a Q-Tip will
also work, if you have fat fingers), and lift the mirror off it's
stop.
4) I then clean the mirror, using the damp Q-Tip.
5) I don't concern myself with getting the thing spotless. You are
more likely to damage the thing with too much cleaning than too
little.
For the record, I have not "cleaned" a reflex mirror on one of my own
cameras in probably 25 years.
William Robb
