Whats the best way to clean refractor optics?

[Astroman]

Hi All,

Whats the best way to clean refractor optics? This is on an 80mm Lens that is coated, I also want to clean the lens, inside of the OTA.

Over a period of time some much has got onto the lens from various modifications, and I want to remove them before they might become problematic.

[The Mekon]

Remove the cell from the tube & clean!

However are you sure it is dirty on the inside? I thought the same for my AP 130 lens after 21 years of ownership. I had cleaned it on the outside a number of times with alcohol so I thought that the remaining dirt was on the inside. Then I decided to clean the reflector way with warm water and detergent. With the tube on the mount I turned the scope to point to the ground. Washed the lens with warm water and detergent. Rinsed with distilled water and presto! clean as a whistle.

[gregbradley]

Takahashi had a write up with its scopes and there would be other resources on the net.

Here's the procedure I have used many times that works well:

1. Hurricane blower, blow loose girt and dirt as much as possible off the lens. Pull back dew shield if it retracts.

2. Using cotton balls and Bintel lens cleaning fluid (its really good and streak free), daub the cleaning fluid onto sections of the lens. Chnge cotton balls regularly. Best to do a quarter of the lens at a time. You want to get the grit and scratchy stuff off here and stains that are easily dissolved. Get the lens a bit wet but not running off down into the cell.

2 With nonscented white tissues, wipe a small section and dispense of tissue. Change tissues constantly. The risk is some grit gets on the tissue and you wipe and scratch. So change often. Wipe in small areas and take it to a streak free finish. You may need to do this step a few times if its really dirty.

3. Do the same for the other quarters and a final look at the lens from a backlit view and see any streaks, bits missed and clean.

If the cell was tight a spray of distilled water with the lens pointing towards the ground somewhat may get dust and grit off early which would be good. You'd have to be confident water wouldn't penetrate the cell and go between lenses though. I use washing like that for exposed mirrors not refractor lenses.

Greg.

[The Mekon]

Greg, yes that is the text book way and I find it cumbersome and results did not leave me satisfied.

I might say that day I cleaned my AP was a hot dry day, to give the lens the best chance of drying out should any moisture have got into the cell.

[gregbradley]

Water penetration is probably unlikely with a well made scope like an AP. 21 years of build up would take some work to clean up.

Greg.