Primary Mirror Question

[icewalking]

Hello!

I know that cleaning the primary is inadvisable, and that they function well even with a bit of a dust build-up, but as a newbie with a nice shiny scope I'd like some advice on this please:

It's a black speck, a little bigger than the image shows (there's also a smaller black dot above it). I'm guessing a blade of grass possibly - no idea how it got on there, but I noticed it after an observing session last night.

Is it worth trying to get it off the mirror, or will this do more harm than good?

TIA

[FrankieValley]

Try blowing it off with a hairdryer.

[MjrTom]

yeah I agree, I use a rocket blower for cleaning dust off my optics.

Worth having one to hand.

http://www.amazon.co.uk/dp/B00017LSPI/ref=asc_df_B00017LSPI6578868?smid=A1OP0QJ84CBJP2&tag=googlecouk06-21&linkCode=asn&creative=22218&creativeASIN=B00017LSPI

[icewalking]

Thanks chaps! I do have a rocket blower, it wouldn't budge the speck though - think I would have to remove the primary entirely to do that? I will try the hairdryer when I get in!

[Cornelius Varley]

Leave it alone.

Peter

[Stephen]

Leave it alone.

Peter

Seconded

[coulthamst]

Hi icewalking. You are not referring to the small black disc (which should be positioned at the exact centre of the primary) that is intended to assist with collimation are you? If so, and it is in the right place - difficult to tell from the angle of your picture - then it should stay where it is.

[icewalking]

Hi icewalking. You are not referring to the small black disc (which should be positioned at the exact centre of the primary) that is intended to assist with collimation are you? If so, and it is in the right place - difficult to tell from the angle of your picture - then it should stay where it is.

Hi coulthamst - it's the mark just north of the collimating disc; it's not very clear on the photo, but is quite prominent in real life!

Thanks for the advice - I think I will err on the side of caution and leave it be for now. Still, it's going to bug me knowing that my nice new shiny mirror is blemished, even if the views aren't affected!

[Zakalwe]

It'll be fine. The risk of causing more damage by cleaning it far outweighs anything to e gained by removing it. It will make no difference to the visual or imaging performance of the scope.

[Damo636]

Don't worry, in no time at all it will be covered with all sorts of debrie and the speck will blend in just lovely. It will have no effect on the views.

[icewalking]

You were all right (of course!) - have just finished a little observing session and the speck made no difference. Indeed, when I brought the scope back inside I saw that it had fallen off!