Advice on looking at a second hand scope

[domstar]

Wow. The almost non-existent second hand market here has suddenly sprung into action and if nobody gets in first, I'll be able to go and see a scope next weekend. The only problem is that I have no idea what I should be looking for to check its condition (it won't be dark and will more than likely be raining or snowing). Does anyone have any tips for what I should look for and what should constitute a deal-breaker? It's a 500km round trip. My wife thinks I should boot the mount to see if it's stable and give the tube a good old shake to see how much it rattles. She's usually right about these things.

[alanjgreen]

Which scope is it that you're going to see?

reflector, refractor, SCT?

[domstar]

It's an achromatic refractor.

[alanjgreen]

Have a look through it in daytime with a nice wide field eyepiece. Look into the light sky (not the sun!!), any blobs or blotches in the view?

check the focuser is smooth and not wobbly.

give it a gentle shake for rattles etc

if you are also getting a mount, get it powered up and do a fake solar system align to get it tracking. Listen to the motors whilst tracking.

do some test slews up,down,left,right

cant say much more as your description of what you're buying is so vague.

[bomberbaz]

do you have a link to the advert, that would help knowing in more detail as to what you are thinking of buying.

[Peter Drew]

Not much to look for in a refractor. Main points to look at are the objective lens and the focuser. The objective should be reasonably clean with no fungus spots between the lenses. The focuser should be smooth in operation with little or no slop. If the telescope is not of high value, the price of the trip added to it might have bought you a new one.

[domstar]

2 minutes ago, Peter Drew said:

The objective should be reasonably clean with no fungus spots between the lenses.

Sorry for my ignorance. You mean look through it the wrong way and look for mould on the tube inside? Also what does slop mean for a focuser.

[domstar]

28 minutes ago, bomberbaz said:

do you have a link to the advert, that would help knowing in more detail as to what you are thinking of buying.

It's a bresser 152/760 refractor probably just ota. The advert is in Czech and there's no photo though I'm hoping he'll email me one soon. If there's no mount, I'll need some further advice on that too.

[Putaendo Patrick]

Could be a very nice telescope! It should look something like this:

I think older models are black and white as above, while more recent versions are all white. As already said, I'd look for mould inside the objective lens, any signs of serious dents or dings which may put the whole scope out of alignment, and a firm focuser which moves freely without too much lateral play.

Look out for any accessories, or lack of them, and factor this into the price. Eyepieces, finderscope, field flattener etc. The telescope fits onto a mount with a dovetail bar - be aware that there are two common types, Vixen and Losmandy. Some mounts can take both, others only one or the other.

Here's the link to the current Bresser 152: https://www.bresser.de/en/Astronomy/Bresser-Messier-AR-152S-760-Hexafoc-Optical-Tube.html#

[domstar]

30 minutes ago, Putaendo Patrick said:

be aware that there are two common types, Vixen and Losmandy.

Thanks- I didn't know that. How will I know which one it is?

Also at 10kg does that mean I need an eq-5 mount? I think I'm starting to go way over budget if it's not included.

[alanjgreen]

Appearance, they do not look the same at all

 

https://www.firstlightoptics.com/adm-vixen-type-v-series/adm-vixen-style-universal-dovetail-bars.html

https://www.firstlightoptics.com/adm-losmandy-type-d-series/adm-losmandy-style-universal-dovetail-bars.html

[Peter Drew]

1 hour ago, domstar said:

Sorry for my ignorance. You mean look through it the wrong way and look for mould on the tube inside? Also what does slop mean for a focuser.

Yes, look through it the wrong way to see if there is any mould on the front lens, this is composed of two lenses almost touching and the mould can grow between them, it would need dismantling to address. Slop in the focused means slack side to side movement. This is a very heavy telescope and an EQ5 would be the minimum suitable mount for visual use.

[domstar]

12 minutes ago, Peter Drew said:

Yes, look through it the wrong way to see if there is any mould on the front lens, this is composed of two lenses almost touching and the mould can grow between them, it would need dismantling to address. Slop in the focused means slack side to side movement. This is a very heavy telescope and an EQ5 would be the minimum suitable mount for visual use.

Well you learn something every day (at least I do-especially here)Thanks for your time.