Paul
On Nov 22, 2004, at 8:14 PM, Bob Blakely wrote:
Bob's OCD recommendations for cleaning bottom of MX pentaprism, screen, and mirror box:
1. Wash your hands. You're not a good OC if you don't.
2. DO NOT TOUCH THE MIRROR! It's a first surface mirror (Al is on top) and can be easily ruined.
3. Remove screen using proper tool, carefully bent tweezers can work, grip tab only, place in proper holder (grips only edges).
4. Turn the camera upside down and LIGHTLY blow particles off mirror with *light* compressed air. (I use purified, dry CO2). Do not blow directly on foam. DO NOT TOUCH THE MIRROR!
5. Hold a small piece of paper in front of mirror to protect it and to hold screen holder out of the way and blow particles off bottom of pentaprism with *light power* clean compressed air. DO NOT TOUCH THE MIRROR!
6. Wind a piece of professional lens cleaning tissue on a toothpick, add small drop of cleaning fluid and clean the underside of the pentaprism using the same method you would for a lens (circle of very small circles from center out.) Do not let wood scrape glass coating. DO NOT TOUCH THE MIRROR!
7. Hold a small piece of paper in front of mirror to protect it and dry and blow any tissue threads off with *light* compressed air. DO NOT TOUCH THE MIRROR!
8. Turn the camera upright.
9. Pick up screen by *edges only* and blow moderate power clean compressed air over both dry sides.
10. Add a drop of dishwashing detergent to a bowl of distilled water, mix, and place the screen in the water to soak for a few minutes. If you have an ultrasonic cleaner, this is where you use it. otherwise swish it around. Rinse several times in distilled water and blow dry with compressed air.
11. Replace screen.
12. Attach short cable release, set MX to "B", lock shutter open using cable release. This locks the mirror up to get it out of the way and to protect it, protect the foam and open the shutter to protect it. Blast the crap out of the inside, be careful of any foam.
13. Release the shutter and close up the camera.
If the mirror has crap on it that does no blow off, DO NOT TOUCH THE MIRROR! Take it to a professional who will replace the mirror if he ruins it.
Regards, Bob...
From: "Hugo Kok" <[EMAIL PROTECTED]>
Hello dear people,
I'm currently doing a long postponed job, namely exchanging focusing screens between two MX-es. Reasons for postponing are of course the trickiness of the procedure. I know of some of the dangers of touching the screens and such. With pentaprisms I have none experience whatsoever. I'm searching for people who have experience with this dirty job because I'm afraid I screwed things up.
What I did is this:
Removed screen, parked it in the holder of the plastic screen box. Next
I looked through the viewfinder to notice some dusty particles. I
thought it to be a good idea to remove these too. So I gently moved a
special micro-fibre lens cleaning cloth over the pentaprism. Looking
through the viewfinder didn't make me happier, to say the least. I
don't know how to describe what I saw; it resembled most a trail of
very tiny oily drops. I wonder where these drops come from: the cloth
or is was it already on pentaprism? Anyway, not being able to remove
the phenomenon I proceeded to place the focusing screen from my other
MX in this camera. Looking through the viewfinder made me sigh a little
(of relief, that is) because there was no visible trace of the oily
substance to be found back on the image in the viewfinder. But still,
there were the dust particles. These are annoying and now I localized
them to be on the focusing screen and not on the pentaprism. Rubbing
with a lens brush did not help; it merely moved the dust from one place
to the other.
This longwinding story comes to an end now, because I'm nearing my current state of misery; I finally tried to get rid of the dust by using the lens cloth. I gently moved up and down ONCE. And now I can see something that is best described as a trace of liquid. It's not dark but transparant.
My question: is there anybody who has done this job before who can provide for some suggestions regarding the whole procedure? Think it would be of help for anyone facing the same situation. One of my questions is for example: what the hell is going on with this special lens cloths? There was no mention of it containing any sort of stuff and I NEVER experienced someting like this (I use the cloth for a considerable time to clean my lenses (front and back).
Anyway, Hope you guys have some ideas.
BTW: the focusing screen in the above story is a wholly matted one with
an extra fine matted centre circle - so no attached focusing aids on
the screen..
Yours, Hugo
=====
Don't it always seem to go that you don't know what you've got till it's gone - Joni Mitchell.
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