Cleaning Optics

[Loki1978]

Hi all, 

I was just after a bit of advice. I recently bought a second hand cpc 800 and the optics were a little dirty. Like they had seen a lot of dew which had caused marks on the inside of the corrector plate and on the mirror. Like lots of water dots.

I bought some pec pads and zeiss cleaning solution. I marked and removed the corrector plate. I cleaned the corrector plate and mirror but I'm actually less than impressed with the zeiss cleaner. I tried several times but it leaves an almost greasy residue. It almost smells like it has a citrus oil in it but I can't see it in the ingredients. It does say it's safe for precision coated optics. Am I being over fussy? I don't want to keep going at it as I would rather touch the mirror as little as possible.

What do you all use. I was trying to get some methanol but its really expensive unless I buy 5 litres. Will isopropyl be better. 

One thing I did realise pretty quick is the need to stay away from the tube through the centre of the mirror as it has a grease on it which is easily transferred to your hands and the pec pad.

 

 

Edited February 14, 2020 by Loki1978

[AstroTim]

I’ve had a similar experience with Zeiss cleaning solution. Worked great on spectacles, but left streaks on binoculars. I thought maybe it was the cloth I was using (although it was a microfibre camera lens cloth) but hearing of your experience makes me wonder whether it just doesn’t work so well with coated lenses. Quite surprised given Zeiss’s reputation in optics.

 

Tim

[Alien 13]

Isopropyl is fine but ideally needs to be diluted with distilled water, the problem with any "wet" cleaner is that it will dissolve a speck of grease but then deposit as a smear when it evaporates,  you then end up with constant rubbing with a cloth to finish off  so I never use any wet cleaners.

Alan

[Waldemar]

Maybe this can be of any help:

Cleaning solution.docx

[Stu]

I would have cleaned the mirror in the same way you do a newtonian mirror ie with warm slightly soapy water and very soft cotton wool balls. Let the mirror soak for a while, then with the surface under water, just lightly drag the cotton wool under its own weight across the surface to remove any muck. Rinse with distilled water (I use RO water from an aquarium shop) and leave leaning at a steep angle to drain. I often use a cool hairdryer to blow the water off and then wick away any remaining drops with the twisted end of a tissue.

The correctors are more robust and I would clean that in a similar way but I'm sure a cloth and cleaning fluid would be fine. I've used the alcohol free stuff from spec savers on my Tak and it works well. I use a brand new Baader microfiber cloth when doing the Tak as it seems to avoid any streaking afterwards.

[Loki1978]

Hi all, 

Thanks for the replies. I have distilled water and isopropyl here. I might just try wiping the smears away without going to town on it. I used to have an RO setup for an aquarium but got rid of it a while ago. I've often used RO but once I had my own equipment I realised that for every gallon of RO produced you waste 4 gallons of 'waste' water.  So I started buying it again rather than producing it myself. 

Good time to be cleaning optics as there's not much viewing to be had with this storm at the moment. 

 

[Loki1978]

Just finished cleaning this scope up and I can say isopropyl with distilled water works perfectly. I used 99% pure isopropyl mixed around 30 /70 distilled.. I'm finally happy with the results now. I'm really not sure what was up with the zeiss product. I'm wondering if it's like most things now where the solvents that do the work are all removed to make the product safe for the general public. Having said that I did try the zeiss on the bathroom mirror and it works well. As AstroTim said I think it has some issue with the telescope coatings used. 

[Louis D]

It could be that the Zeiss solution is intended to dissolve really tough grunge such as tree sap, but doesn't actually wipe cleanly away and requires a follow-up with another cleanser.