First telescope questions

[Boros]

Hello from  another  beginner!  I'm more of a photographer to be honest, it's been my main interest for over 50 years, but I've never dabbled with astro or planetary photography. So this troubled spell we're going through seemed like a good time to give it a try.

So being a Scot and not wanting to lay out lots of money on an initial foray into the sport, I kept an eye out for a s/h scope.  I already did some research and decided that  rightly or wrongly I probably needed to get a refractor or a maksutov. So after a couple of weeks I stumbled across this, it's a Celestron Nexstar 102GT with computerised mount. When I went to see it, the chap said he just noticed that the hand control wasn't working and he had just put new batteries in it, that's a bummer I thought! Anyway the thing is in immaculate condition, he had it advertised for £90, so I decided to have a haggle seeing as the mount was potentially smoked, and I got it for £50 sterling!  Anyway on getting it home I immediately pulled and tested the batteries, they were fine so put them back and plugged it in and the handset immediately lit up and then proceeded to apparently work as it should, so who knows. I'd read the reviews on it and they are very mixed, some people seemed to like it others not so much.

I couldn't wait to try it though and I managed to get some clear sky last night, just enough time to get my Fujifilm XT2 strapped on and a few pics taken before the clouds started rolling over again. I'd bought a T adaptor for it and it screwed straight on to the Celestron once I'd removed the the diagonal.  For what I paid for it, it's an absolute bargain, and it could no doubt give me some serious enjoyment. 

 I've attached a pic that I took last night and for a first attempt I'm more than pleased.  However I do have a few observations that might mean it will be a stop gap.  First one is the length of the tube, with the 45 degree diagonal you almost have to sit on the ground! This seems more suited to terrestrial use, when elevated to view objects in the sky it's unusable, and with the tripod fully extended it's even worse, you just need to breath on the scope and it induces the wobbles, I tried adding weight to the tripod it helped but not enough to alleviate the problem.  So as far as I can see it does a reasonable job of imaging, but I'd need to make some adjustments and purchases, like a 90 degree diagonal which might help and definitely need to do something with the tripod, but keeping the motorised mount if possible. Any suggestions from you learned gentlemen would be appreciated.

[RT65CB-SWL]

Hi @Boros and welcome to SGL. 

Well for £50.00GBP you got yourself a real bargain. 

I cannot help much regrading what the best coarse of action is, apart from investing in a heavy duty mount and tripod/pillar or have pillar permanently in the garden as this help will reduce vibrations, or if you have the necessary space maybe an obsy too, plus it will give you some and your equipment protection during the winter months. Also investing in a heavy duty mount, will be more accurate for imaging DSO's.

Edited July 29, 2020 by Philip R

[laudropb]

Hello and a warm welcome to the SGL. You certainly got a real bargain there.

[Boros]

Hello  Thank you I really did. It is a good scope but just has the issue with the unstable tripod made worse by the long tube which necessitates extending the tripod to it's full extent where it's really unstable. Really need to find a way to stabilise it, I've tried weighing it down which improves it but not substantially.

[Cosmic Geoff]

Great deal for £50.  The mount looks the same as my Nexstar SLT.

TBH, the long 102mm scope looks a bit much for that mount. As well as being long, it may be exceeding the weight recommendation. I have used mine with a 127mm Mak (more wobbly than I liked) and a 102mm Startravel, but felt motivated to get a used EQ5 mount (not powered) and I also got a spare mount "bowl" and fitted 3 wooden legs for a permanent and less wobbly garden mount.   You could try something similar if you are handy with tools.

Ideally you want a better class of mount, (e.g. EQ 3 manual, motorized or  Synscan) but this will sadly cost, even second-hand, more than you paid in the first place.

Most people use an external battery or PSU with the SLT.  You will get a better performance too if you replace the 45 deg diagonal with a 90 deg star diagonal, even a cheap one.

[jonathan]

One thing you can do for free (or relatively cheaply), after you have acquired a 90 degree diagonal, is to get yourself as comfortable as possible at the eyepiece, relax, and enjoy the view.  It can be a skill in itself to find the best observing position, that's why many astronomers invest in their seating arrangements as carefully as their mount and telescope.  There are various observing chair types available, some are similar to ironing stools with an adjustable height seat pad on a rack of sorts; I acquired a drummer's stool from a charity shop for about a fiver I think which adjusts up and down on a giant thread, I find it comfy and very easy to use as it can be sat on in any direction (there is no back) and is also very easy to get on and off.

Being comfortable at the eyepiece should allow you to observe without touching the scope, however focusing will still be a problem as far as vibrations are concerned, unfortunately the remedies involve financial investment in more kit.  Main options include a heavier-duty mount / tripod (which could cost a few hundred, extra for motorised or goto), rubber pads under the tripod feet (provides only a slight improvement, so I'm told), or an electronic focuser, however this may add too much weight and cause your mount to struggle seeing as it's likely already at or over it's carrying capacity; keep in mind that if you add weight to one end of the telescope, e.g. the eyepiece end, you would need to rebalance the scope either by moving it forwards in the mount (if that's possible) or by adding some weight to the front of the scope, if the scope is unbalanced in the mount then it will struggle to slew and track, if the scope weight passes a certain threshold the mount will struggle all of the time.  Driving the scope from a DC source other than batteries will help but it won't cure the underlying problem.

Edited July 30, 2020 by jonathan

[Boros]

Okay all thanks for your advice, I'll update when I have made some progress.