Second (and third) hand telescopes

[keybaud]

What are the pitfalls that I need to look out for when buying second hand telescopes and are there things that may be wrong that can actually be corrected, cleaned or repaired at a reasonable cost, so may not be a reason to not purchase?

[NGC 1502]

What are the pitfalls that I need to look out for when buying second hand telescopes and are there things that may be wrong that can actually be corrected, cleaned or repaired at a reasonable cost, so may not be a reason to not purchase?

Hard to cover everything, but the basics -

Look at optical surfaces, some dust no problem and is normal, but mirrors should have the bright coating present on the whole surface, no digs or scratches.  A recoat could sort dodgy coatings (take the cost & hassle into account) but won't sort other damage. Collimation (mirror alignment) can be sorted as a DIY fix.

Lenses, again a bit of dust no prob, but digs & scratches will be there forever.

Mounts - look for corrosion, bent sections, all adjustment knobs free to turn & not seized.

Electronics - ask for a demo.

Best to take someone familiar with telescopes if at all poss.

There are definitely bargains out there if you are careful.......

Good luck, Ed.

[Nigele2]

My two where both secondhand on ebay.  As Ed says you need to ask all the questions but with Ebay you are fairly safe refund wise as long as you asked.

And value wise well you can see what I spent.

With most you can assume the EPs will be starter stuff so allow in your budget for new better ones.  You can store the starters to sell on with the scope when you upgrade.

But I get the feeling thousands of telescopes are bought and hardly used so again as Ed says there are real bargains to be had.  Just be patient and await a bargain.

[keybaud]

Thanks, both.

[Avocette]

Most of the common Dobs have melamine coated chipboard/MDF bases. These work well and can be improved with a bit of attention to bearings and teflon friction pads. They are vulnerable to damp however both from dew in use and humid storage conditions so look out for signs of swelling around the edges. Beware also of the changes that take place over time. With the SkyWatcher range we can see that the colour scheme has varied from blue to 'diamond black' with white for Dobs, but parts also change in time such as the replacement of rack and pinion by Crayford focusers, and in some models the addition of the 2" eyepiece capability. The standard eyepieces supplied a while ago may have been Plossls rather than 'Super MA' types. Some such changes may be improvements, others more likely 'value engineering'. I think this particularly applies to the collimation screws and O rings fitted to some reflectors these days. You may not need to upgrade with a set of Bob's Knobs on an older exmple which had knurled screws and springs. Anyway just a couple of thoughts to bear in mind when you get into buying mode.