Does this need cleaning?

[eifionglyn]

As the title. Attached is the primary on my Skywatcher Exploter 200. It's kind of come out on the photo, but there is quite a bit of dust and a few larger blobs of dirt visible on the mirror. I must have had it some four or five years now, and have never done anything to it so far, not even collimated it. (I've put a collimating cap in every now and again but it always seems to be lined up to me - maybe I'm just lucky or don't know what I'm looking for).

So would it benefit from cleaning? Would this amount of dust affect the views noticeably or am I better off just leaving it well alone.

[SnakeyJ]

Looks to me like it might benefit from both cleaning and collimation! Is the picture taken with a camera over the open focser draw tube (not centered) - this and the strong flash probably makes it look worse than it actually is. Certainly seems to be some drying marks, dark dust bunnies - but not sure what the white dots and streaks are, but these seem to be on the secondary.

I had some issues with paint flakes comming off my first 200P, which looked horrendous but was actually really easy to deal with once I figured out the source!

Hold fire for the moment and wait for a few other (more experienced) views/responses - but if at the end of the day it does need to be cleaned it is not too difficult or scary a job and there are some good video tutorials - preparation, calm and due care are the best ways to avoid any accidental damage.

[Moonshane]

you probably won't see any benefit after cleaning but less dirt attracts less dirt so maybe it's worth it. not a difficult job, just be careful.

you can clean a mirror pretty well without even touching the surface. I rarely ever clean my mirrors, but when I do I usually just soak it in a bowl of luke warm water with a tiny bit of washing up liquid in, then stand vertically in the bath on a towel and rinse off with a shower head (again luke warm), then rinse off with RO water from an aquarium. then reinstall and collimate.

[eifionglyn]

No, the picture's taken pointing a smartphone camera actually down the open the open aperture of the OTA, rather than down the focuser, so don't take the off-centre view as an indication of out of collimation. The white curved section in the top right corner is actually the back of the secondary. I think the white flecks might be artefacts due to the flash bouncing around in there, and some of the marks at least are actually reflections of the ceiling rather than on the mirror. It's not the best picture to be honest. I've just always read advice about leaving mirrors be unless they really need cleaning, but mine is now so dusty that I'm starting to think it needs it. I certainly wouldn't shave with it in it's present state!

[SnakeyJ]

you probably won't see any benefit after cleaning but less dirt attracts less dirt so maybe it's worth it. not a difficult job, just be careful.

you can clean a mirror pretty well without even touching the surface. I rarely ever clean my mirrors, but when I do I usually just soak it in a bowl of luke warm water with a tiny bit of washing up liquid in, then stand vertically in the bath on a towel and rinse off with a shower head (again luke warm), then rinse off with RO water from an aquarium. then reinstall and collimate.

Any ideas on those white marks/streaks Shane?

Sorry, eifionglyn you're reply came just as I posted!

[eifionglyn]

Here's some better pictures. Definitely in need of a clean. Not sure how much this would have affected the views, but it can't have been helping!

Not perfect but certainly much better. Followed the astronomy shed video tutorial on youtube, lukewarm water, fairly liquid and fingers. Then a good rinse in tap water followed by distilled water.

Meant to be clear tomorrow night, we'll see if it's made any difference. Or we probably won't see. Assuming I haven't ruined it then being a fallible human and with no way of making an objective comparison I'll probably convince myself it's helped even it it's not a real detectable difference.

[Moonshane]

unlikely to have ruined it. looks good. I doubt you'll see a difference but you'll feel better about it probably.

I washed my 12" mirror the other day as there was a small mould spot on it when I bought it which had been bugging me for a while. I tend to use exactly the same method. O soften my fingers in warm soapy water before touching the mirror.

[LukeSkywatcher]

Looks good to me too. Should last you a few yrs now without more cleaning unless you decide to give it a mud bath,LOL.