Cleaning the main / back Mirror on a MAK

[Ali C]

Hi

I have recently bought a Celestron 127 MAK as my first Scope.

It has been happy days so far, the 3 star GoTo set up is a really nice and easy to use feature.

I have noticed a piece of dust / dirt on the main mirror. Any tips on how to clean the main mirror or is this a job for a specialist.

Thanks

Ali

[Cornelius Varley]

Leave it alone.

Peter

[nightfisher]

dont touch it, mirrors should only be cleaned as a last resort

[Ali C]

Fair enough,

Once I get a bit more competent I hope to use the scope for astrophotograpy ( lunar images ) is a piece of **** on the mirror likely to have any noticable effect with viewing / imagery.

[Cunhaval]

Unless it's a splodge the size of a teacup, it will have no discernible effect.

Best left alone.

[JamesF]

Generally, I'd agree with the advice "leave it alone". However...

I discovered that something inside my Mak was loose the other day, so I marked the position of the front corrector lens/reflector assembly and unscrewed it. With the scope lying on its side (this is important I undid the grub screw on the focuser knob and gently tipped the scope forward so the mirror would slide down the centre tube and out.

Turns out that the locking ring that holds the mirror in place wasn't and the mirror was free to spin/rock/slide back-and-forth on its mount, which might explain a few issues I've had. After fixing that I looked at the mirror and couldn't believe how filthy it was, so I decided to clean it. Did the same with the secondary mirror and both sides of the corrector lens before reassembling it as they were all quite disgusting. (This is a blue model so it's hardly factory-fresh.)

I've not had a chance to check the collimation or image quality since, though I think clear skies are forecast here for the small hours so if I can stay awake that late I might well try tonight. The reflection from the main mirror is certainly a good deal brighter and sharper than it was though.

It looks like it may well be possible (and easier) to remove the entire back-plate of the Mak by undoing the allen bolts, but as I already had it apart by the time I worked that out I didn't bother to test the theory.

I'll re-iterate my initial comment however. Normally I wouldn't clean the mirror and I'd suggest it was best left well alone. It was just that I happened to have the scope apart anyhow and noticed quite how bad it was.

James

[Ali C]

Hi James

Thanks for the advise, it is a new Celestron 127 MAK ( bought 1 month ago ) , I was observing the moon last night, It was a highish angle and I think a paint fleck or similar has fallen onto the mirror from inside the tube. Looking through the corrector it is about 0.25 mm long little triangular piece. Is this likely to spoil a photo ?

[JamesF]

I see no reason why it would. Doesn't surprise me that something like that has happened though. The corrector/secondary unit is quite a snug fit on the threads and I'd guess odd bits of paint/plastic can be dislodged when it's installed and those might fall onto the mirror in time.

James

[Ali C]

Thanks, i'll not let the OCD factor kick in and leave well alone.

Hopefully it will move to the edge of the mirror, in time.

Cheers

Ali C