Thoughts on cleaning the correstor lense

Hi

I took a look at the corrector plate a couple of nights ago and I noticed a number of tiny bright reflecting spots on the corrector plate. Now I havent noticed any degredation in the views i am getting and these spots are not particularly apparent unless you go looking for them. There is dust build up on the lense but not excessive and again I havent noticed any decrease in the views. The thing is these spots "could" be little globules of tree sap as where I observe in the back garden is in front of some trees. I understand this is not good.

So I have a choice which is;

1) Leave alone as it isnt affecting my views at the moment and I may do more damage by atempting to clean ie never clean; (I like this choice very much!!!!)
2) Clean immediately as if it is tree sap it will ultimately cause degredation due to acid etc. (hate this one as it scares me to death)
3) Wait until I really have to clean the corrector then clean it removing dust and all foreign crud in one go. (Or find someone who knows how to do it and give them a few bob for the service!!!!!!!!!) (Can live with this one)

Anyway I would be interested in knowing which is the best view to take.

DB

I'd be inclined to suggest the first option. Avoid cleaning at all costs because chances are you'll just make things worse!

Bart.

Dave - tree sap is bad - but AFAIK only on coated lenses. If the corrector plate is just glass, it should be fine.

However, you should check it out. Perhaps an SCT forum or cloudy nights.

As it happens, I recently purchased the Astro-Physics cleaning kit - it contains two solutions. One for general crud and one for bound materials - the second solution will lift most bound crud by disrupting its molecular bonds. It was expensive...

If your research uncovers the need to remove the possible sap, you can bring your OTA or corrector plate here and have a go with the AP stuff.

Cheers
Dave

Hi Dave,
If you find that the image is unaffected and you are not happy going near the corrector, , then I'd be inclined to leave it. You'd be surprised how much dirt and grime you can get on the corrector without affecting the image quality.

If you are going to clean it, use iso-propyl alcohol from a local chemists, that'll do the trick, do not use scented cloths or glasses cleaning cloths, they7 "can" damage the coatings.

You think it is tree sap, doesnt this stuff harden with time into amber?? If it was me, I'd remove it

Dave,

You find these spots a lot on SCT plates, I doubt they are tree sap. Most often they are caused by moisture drying and leaving behind sediment. The best course of action is no action! In two years with a C9.25 SCT I only had to clean the corrector once and that was because one evening while setting up in twilight a bird dropped a 'payload' on it!

Unless these spots are proud of the surface, i.e. they contain more than just impurities which have distilled out of water, your best bet is to leave it alone. I use a camel hair brush (or even one of those lens pen brushes) to lightly remove any dust. I only do this very occassionally. Never do this while the scope is damp or your just get streaks. Best done during the daytime while the corrector is very dry.

You find these spots a lot on SCT plates, I doubt they are tree sap.

My corrector plate has quite a number of small 'splotches' on it. Being near enough to the sea I suspect a little salt in the moisture mixing with the coating at night being responsible. It doesnt cause problems so I've never cleaned it.

The one thing I do do occasionally is blow the dust off it with a hairdryer on a cool setting!