SingAstro

Hi all,

After storing my telescopes in their original boxes for a long time, I finally have the time to pick up the hobby again. On my ETX90, however, there are some blotches on the optics. They look like what you would get after water dries off from a surface. In addition, there are some strands of hair-like particles in the middle of these blotches. Is this a fungus problem?

Thanks.

unfortunately, yes....
you should have kept the scope in a dry box and minimally, a sealed plastic container with a good supply of thirsty hippo..
you can try to use isopropyl solution to clean the blotches if its only on the surface but if the stuff is behind the corrector plate, then you have to unscrew the lens assembly to clean it. make sure you mark off EXACTLY where you started to screw back to the same spot, otherwise your collimation may be affected.

Looking on the bright side, the blotches won't have an observable impact on your scope's performance. Just make sure to store the scope properly after the clean-up so that the fungal growth doesn't recur.

ebeyonder wrote:Hi all,

After storing my telescopes in their original boxes for a long time, I finally have the time to pick up the hobby again. On my ETX90, however, there are some blotches on the optics. They look like what you would get after water dries off from a surface. In addition, there are some strands of hair-like particles in the middle of these blotches. Is this a fungus problem?

Thanks.

Yes, but don't worry too much about them. I say no impact at all at the eyepiece.

Just make sure you store it properly from now on.