smudges on primary ?

[joselin]

Hi

I recently bought 250xp skywatcher, upon inspection of the primary mirror with the naked eye i couldnt see any marks or dust etc but when i decide to have a good look with a tourch of the workings, nuts and bolts etc i noticed a white'ish film/smudge like appearce over the primary mirror.

Should i be concearned or is a normal residue from a polishing agent ?

thanks

[kniclander]

I wouldnt worry about it - I don't think a mirror would ever look perfect under torchlight and you could drive yourself mad. Alternatively, you could go over to Cloudy Nights where the good folk love to drive themselves and each other mad over such things .

[barkis]

Aluminium oxidises after a while, and that can have a milky white appearance.It actually provides the surface with a natural protective layer.

I would not worry too much about it. Just remember a dirty mirror will work better than a badly cleaned one.

Ron.

[Milamber]

Never, ever look at optics with a torch... it's not good for your heart since it makes small particles look enormous. As Ron said, a dirty good mirror works much better than a clean scratched/smudged one.

Arthur

[Deneb]

Sounds like the Coatings on the Mirror !

[The Warthog]

If it really bothers you, give it a good scrub with a Brillo pad, then you'll realize how good it was before you did that.

[albedo0.39]

Never, ever look at optics with a torch...

Or an 8 x White LED version... you might die of heart failure.

Actually, I did and whilst I was shocked, I was not so unhappy. I did however see some marks that were definately evidence of dirt. Considering it had just been re-silvered, I decided to clean with demineralised water.

It now looks mint - even under torchlight ! There are plenty of "how to clean your mirror" articles on the interweb and like collimation, once you know why and how, you will not be so worried.

Rgds

Steve