dust on primary

[rightguard]

my 200p has quite a big layer of dust and other bits on it and im just wondering if this will dramatically decrease the image quality?

secondly, whats the best method to clean it? ive got a lens cleaner pen with a microfibre cloth, so how about some alcohol handrub gently rubbed in and rubbed off with the cloth?

[brantuk]

If the dust layer is thick then it might need a clean. But don't use lens cleaner or alcohol - you could damage the coatings. Usually distilled water is used to clean mirrors

[rightguard]

thanks will try tommorrow

[brantuk]

There's a thread somewhere on here describing a complete mirror clean and all the stuff you need to consider - it's quite an involved (but easy) process. You need to be very careful not to touch the mirror surface.

If I can find the link I'll post it here for you. Meantime look up in Youtube

[rawhead]

Have a look at this:

[brantuk]

Just found this link

(Rawhead just beat me to it lol)

[MikeD]

Have a look at

from Steve "Steppenwolf "

That's how I've always done it.

Mike.

[MikeD]

Doh, Answers like buses.

Mike.

[rightguard]

thanks for all the help

I can't sleep so I bit the bullet and just did it, going against brantuks advice.

used some alcohol hand rub and gently wiped accross to get most of the dust off then used a microfibre cloth to rub it off. may not be the best way but its seemed to do the job. ive attached a before and after, JC, i didnt realise just how bad it was until i took it out of the tube

hopefully visual will improve next time im out.

[brantuk]

Certainly looks like it needed a good wash - you'll know how good you've done it when you first look at the views with it

[jimmyjamjoejoe]

Generally touching the mirror is a bad idea, even the smallest of particles can leave those tiny "hairline" scratches, which aren't generally a problem unless it's done many times.

Most people just run some water over it, maybe even soapy water, then rinse with distilled water and leave to dry naturally (distilled water contains no impurities so leaves no watermarks).

Either way, it certainly looks like you made one hell of an improvement

[Moonshane]

I think on the whole coatings are harder then many people think now but it's still not a good idea to clean the mirror unless it really needs it and even then I suspect the improvement will not be vast visually.

my main concern with your method would be tiny grains of grit etc which may be scraped across the surface and damage the coatings, opening up the silvering to corrosion. that said, it may also be just fine.

[Parus major]

Have a look at this:

That's the chappy from Farpoint Astro so I'm sure he knows what he's doing.