Lens Cleaner

[lhuchison]

I'm just about to make my own lens cleaner with 70% pure alcohol and 30% distilled water. do i add a drop of fairy washing up liquid to the mix?

I'v checked on the net but most of these solutions are for glasses lens cleaning. What about for astronomical use? Liquid soap or just alcohol and water?

Do you think the proportions are correct? Thanks. P.S looking very clear tonight here in the south east, at last!!

[JamesM]

This is an interesting question. I have read instructions that details 50/50 with and without washing up liquid. The key thing is that the objective will have some form of coating on them (glasses aren't always coated) and so I would be very wary of using any detergent in the mix. Mirrors on reflecting scopes can be washed gently in soapy water but the silvering will typically have some kind of protective coating on it (those from orion optics certainly do). The other issue is using the right cloth as most instructions tell you to use USP grade pure cotton, which other posters have claimed is difficult to get hold of and I don't know of any supplier.

You might like to cast your eye over

video for a suggested technique for cleaning eye pieces or alternatively

one if you are cleaning an object lens on a refractor. Interesting the latter video claims that you should not use your breath whilst the first says its ok - I suppose you can only take your pick.

James

[E621Keith]

I wouldn't use soap. It's go to leave residue on your lens. Alcohol and water will evaporate, soap will not.

Also, how pure are your alcohol and water. Optics cleaning ones tends to be very pure.

[Daddystu]

I've just made up a 50:50 mix. Isopropanol (99.5% purity) : Deionised water.

I have access to lab grade acetone too but to be honest i'm not certain which solvent would be best.

[hunterknox]

I would also worry about salt residues from washing up liquids.

[E621Keith]

You need distilled water. Mirror cleaning instructions suggest deionised water will leave residue.

I won't use acetone. You don't know what kind of plastic they use in an eyepieces and acetone is very effective in melting some of them.

btw, why not just use IPA? Sometimes I use Eclipse to clean the streak left behind by Baader fluid and Eclipse is just very pure IPA (<5ppm contaminant)

[lhuchison]

Thank you for the tips. i'll leave out the washing up liquid