Did I ruin this lens?

Started by msloane, 05/12/2005 03:26AM
Posted 05/12/2005 03:26AM Opening Post
I may have just made my first somewhat costly mistake in my foray into astronomy! I just purchased a used Celestron NexStar 5, which appears to be in great shape, but quite dirty. Included with the scope was an Orion lens cleaning kit, and a Celestron 2x Barlow lens.

I was proudly cleaning the exterior of the scope and lenses, and I noticed that the glass surface of the barlow was somewhat smudged. I got the cleaning kit, which had a can of compressed air, and read the instructions.

I was blowing off the dirt with the compressed air, when I accidentally shot a blast of moisture right at the lens. It looks like water vapor got inside the lens, and then dried, leaving a smudge of residue about 1/4th inch in diameter. I guess I wasn't holding the can straight upright, which caused the propellant or some liquid to spray out.

Anyway, is there any way to clean inside the barlow?
How bad will a smudge like this be?
Is the barlow ruined?
Posted 05/12/2005 06:21AM #1
This is common with compressed air in a can. Some use hydrocarbons for a propellant. Never tilt a can when in use. I use canned air, but I am careful to test fire the can before using it on something and them only with the can leveled.
The stain should be on the outside of the lens, I don;t see how it could have gotten on the inside. If it did then it must have been condensation from the propellant cooling the lens. If it is on the inside then it will have to be disassembled to clean it. The stain can probably be removed with pure alcohol or if there is no plastic you could use acetone.
I assume you have tried to clean the stain already with the cleaning solution you have. So if it is on the inside, you may want to get some one that is experienced in disassembly and cleaning to do this for you.

[SIZE="Large"][/SIZE][COLOR="Blue"][/COLOR] Floyd Blue grin
Amateur Imager
Posted 05/12/2005 04:37PM #2
Hi:

I have never done anything like this myself.... smile

I am quite sure you have not ruined the barlow and with some care you can disassemble the lens and clean it. Check out the TeleVue website, they have some good instructions for cleaning lenses.

jon