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Old 01-04-2008, 05:58 PM
ausastronomer (John Bambury)
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Join Date: Mar 2005
Location: Shoalhaven Heads, NSW
Posts: 2,620
Quote:
Originally Posted by Astromelb View Post
Dear enquirer,

I have been professionally hand crafting reference grade telescopes for many years and rarely need to clean mirrors, are you guys taking care of your optics, it sounds like a problem for a few of you.

Rgds,
Astromelb.
Barry,

That is all fine in theory. It also works in many situations. However, you shouldn't assume that people don't look after their equipment because they have a need to clean the mirror on a more regular basis than you do.

If you have an observatory and don't need to transport the telescope, that in itself goes a long way to keeping the optics clean. If you travel with a scope to remote dark sites, some of which can be exceptionally dusty, as can the roads you travel on to get there, it isn't always a simple task to keep dust and crud off the mirror. The only time the lid on the mirror box on my 18" Obsession is removed is when I am observing, yet the mirror gets covered in crud very quickly. This gets further compounded when I observe from home right by the salt water. We get regular dews which are very corrosive because of the high salt content and this ultimately ends up as "acid rain" on the mirror after it condenses and is held on the mirror by all the crud that collected whilst out in the bush. If I waited years to clean my mirror, I would be using a reflective surface of pure aluminium chloride with a reflectivity co-efficent of about 8%. That doesn't work for me.

I also have a tube scope which I cap when not in use. I actually use rip stop nylon fabric caps which allow the scope to "breathe" and help to prevent the buildup of mould and mildew. Capping a scope using a solid non breathing cap when it has a dewed mirror, can do more damage than good.

Cheers,
John B
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