At 1:14 AM +0000 8/9/02, olympus-digest wrote:
>Date: Thu, 8 Aug 2002 13:12:44 -0700
>From: "Norman S. Nadel" <nsnadel@xxxxxxxxx>
>Subject: [OM] 2.5 OM Questions
>
>Question 1. Does anyone know what the clear light weight plastic bags are
>made of .. the ones that Olympus uses to wrap the OM lenses .. Cellophane?
>.. Polypropylene? Polyethylene? I want to order a supply and make sure
>that the material does not emit fumes or react with the lens or lens
>coatings.
Ordinary ziplock freezer bags from the grocery store work well. These bags are
made of polyethylene, and emit no fumes. Be aware that the ziplocks with a
moveable plastic zipper don't seal perfectly, as there is a little triangular
hole where the flaps split to enter the zipper body.
>Also, any suggestions as to where I can get them and best all around size.
>Most places seem to sell only in lots of 1000.
Grocery stores deal in smaill quantities.
>Question 2. Any tips on cleaning the OM mirror?
Yeah. Don't do it. The mirror surface is pure aluminium, which is very soft,
and it's almost impossible to clean such a surface without scratching it. Dust
on the mirror has no effect on the pictures, as the mirror is not in the
optical path when the film is being exposed. The only effect of a dusty mirror
is a little haze in the viewfinder.
If it's so dirty that you must clean the mirror (that is, the scratches will be
less a problem than the dirt they replace), first hold the camera front-side
down and blow as much dust off and out as possible using compressed air (which
can be bought in cans from larger photo suppliers), and then very very
carefully swab the surface with a cotton ball wetted with 90% (or better)
alcohol (isopropyl or ethyl), and then wipe the excess alcohol off with a few
more cotton balls or soft cotton or microfiber cloth. Use a clean hemostat to
hold the cotton balls, but ensure that the hemostat touches nothing except
cotton.
Practice on something unimportant first. Verify that the chosen alocohol
leaves no significant visible residue by using it to clean a piece of
already-clean glass, allowing it to dry, and inspecting with a bright light and
a dark background (so any haze will scatter light and be obvious against the
dark background). Denatured alcohol is intended to thin shellac, and usually
leaves a residue because great purity isn't required for shellac..
If the mirror is that dirty, perhaps the whole camera needs a CLA (clean,
lubricate, and adjust). It's far easier to clean a mirror that isn't installed
in a camera, as one can immers the mirror in alcohol and just wash the dirt off.
Joe Gwinn
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