Stain on Meade 8" LX90 mirror

[eddiedunlop]

I am considering buying a second-hand Meade 8" LX90 LNT that's about 6 years old.

When inspecting it I noticed the mark on the mirror shown in the picture. It appears to be a dried-up streak of some liquid (dew?) that has run down the mirror and dried.

Also, shining a torch on the mirror shows up a lot of 'specks'.

Will these defects affect the performance of the scope?

Besides that marks on the mirror the scope is in good condition. The price being asked is around $1600. Is this reasonable for a scope of this age?

Any advice will be appreciated.

[asimov]

I don't think it'll overly affect performance, although it'd be better if it wasn't there.

As for the specks - these form over time on an SCT mirror in any case, so I wouldn't worry too much about them. I don't know about prices, but I'd be trying to beat him down a tad & maybe clean that mirror at a later date..

[Darth Wader]

Hi Martin & welcome to IIS.

A mark that small shouldn't affect your views... I've seen a few mirrors which were in pretty poor condition, yet their owners dragged them out night after night without complaint. I'd query it with the owner to see exactly what it is, but if it's nothing more than water (and if it can be removed, not sure about that model), you could wash the mirror. I've no idea how it's done, but there are guides all over here and the net. I can't help you with the price query, hopefully another 8" LX90 owner will see this thread.

At a guess I'd say the "specks" on the mirror when you shine the torch are more than likely particles of dust.

Cheers
Wade

[renormalised]

The marks you see won't degrade the performance at all. They're merely cosmetic. You can get it cleaned once you buy the scope, but it shouldn't make much difference, except for you knowing they're there:)

For $1600, it's a good buy if it's in good condition. You'll pay up to $2500 for one brand new.

[stephenb]

Martin, one piece of advice I received when I owned am LX90 8" and LX200 10" - Don't shine a torch down the tube. It will freak you out. The light from the torch exaggerates every miniscule speck of dust and it looks worse than it really is. As others have said, perhaps inquire with the owner to establish what the stain could be, but I'll also bet you'll never notice any degradation in viewing.

[mozzie]

no worries with the stain or mark easily cleaned and as for the primary they do get a bit of dust etc on them and in the scope...don;t worry about the torch test in a sct you might find more then you bargained for :lol::D..
sounds like a great buy!!!!!!!

[byronpaul]

Martin, shoudn't be too much of an issue if it's on the mirror surface. Most likely caused by excessive dew which has formed and then run down the mirror.

Would be better if it was on the outside of the corrector plate and not inside on the primary as that would be easier to clean. Having said that, as an LX90 is more of a visual scope, you don't clean the optics unless they really need it .... and from the photo of the scope you've indicated, they look fine.

I've had an LX90 LNT for a couple of years. GREAT scope. I haven't yet cleaned the optics despite them having a bit of dust, spotting from dew, etc. Despite all that, views from a dark sky are fantastic and you don't see the minor dirtiness on the mirror.

Price sounds alright if the scope is in really good condition. The scope is worth what somebody is happy to pay for it. If you can knock the seller down a bit, then even better.

Make sure you can move the scope tube in all directions with the Controller - up, down, left & right, just to check the drives, etc.

Any eyepieces or other accessories included?

All the best.

[eddiedunlop]

Thanks everyone. Your advice was very helpful.
Paul, the scope comes with stock-standard eyepiece (28 mm Plossl) and diagonal only.