Please help replace the mount on a Nextstar 130 SLT

[Nargos_1]

I am trying to replace my old Nextstar 130 SLT's abominable mount and am looking for some help understanding what I can buy that would be compatible with the barrel? The Celeron website says that the mount uses a "Vixen/ CG5 saddle plate" which means nothing to me. Only some mounts say what they are and some are mini Vixen? Am I write that it is the Vixen bit I need to worry about and full size???

I just want a stable mechanical mount after a horrible experience with the nextstar system which never worked properly and was way too shaky, frustrating me into giving up using the scope and then the nextstar bit failed totally.

I would also like to keep the price below £200 if practical.

Thanks for your help!

[Davey-T]

Hi and welcome to SGL, what are your requirements, are you happy with alt / az or were you planning on imaging at some time in the future ?

Not much around for £200.00, an iOptron SmartStar Cube Pro at £285.00 may suit or have you tried second hand sites like UK Astro buy and sell ?

Dave

[jonathan]

CG5 would refer to a Celestron CG5 mount, however it's best if you measure the width of the mount 'bar' to give us a starting point.  I have a CG4 mount and also an EQ5 so I can check what widths they will accommodate, I'm fairly certain the EQ5 / AZ5 should be fine, not 100% sure on the EQ3-2/CG4 without knowing more.  The mount bar will be something like this (probably shorter).

I would recommend looking at an EQ3-2 / CG4 (almost the same thing) or an Alt-Az such as the Sky-Watcher AZ5 Deluxe Alt-Azimuth, paying attention to the load capacity of the mount and tripod, both of these mounts are 5kg.  Remove the tube from your mount, fit the heaviest eyepiece that you own and anything else you would typically have on the scope, then weigh it as you might a piece of luggage, or if you have a set of bathroom scales weigh yourself without the scope then with to get the weight of the scope in kg / lbs, just be very careful not to drop it if using a luggage sling or whatever!  The closer the scope weight is to the carrying capacity of the mount, the more vibration you'll get and strain will be put on the gears (and motors if it has them).

Looking at the original mount load capacity on the Celestron website, it states 3.6kg (assuming that the mount is near to capacity with the scope fitted, the scope might weigh just over 3kg).  The AZ5 states 5kg capacity so that sounds like it should be a good upgrade (the 130 is not a heavy scope in general terms), there are plenty of other mounts around so take your pick, just keep that weight and load capacity in mind, and don't forget to factor in the weight of tube rings if you decide to go that route (they may not be necessary).

Motor drive can be added easily to the EQ3-2/CG4 mount, either dual axis or single axis (only require single axis for simple tracking), if you wanted a solid goto then there's the EQ3 Pro Goto version for £419, Alt-Az has a few different options for Goto including BYO wifi device (keeps the cost of the mount down, but might be obsoleted if the app is discontinued) such as Sky-Watcher AZ GTi WiFi Alt-Az

You could look out for a used scope bundle that has the mount you want, then either keep and use the scope too or sell it.  Stick to popular brands such as Skywatcher, Celestron, and others that are sold by companies like First Light Optics and (fingers crossed) you shouldn't go far wrong.

 

Edited December 12, 2020 by jonathan

[Peter Drew]

A secondhand Vixen SP or GP mount would be the best bet for around the £200 mark.      🙂

[Cosmic Geoff]

You could use any mount you like, provided it accepts the Vixen style dovetail rather than the Losmandy dovetail used with bigger and heavier scopes and mounts.

You could use an alt-azimuth manual mount, an alt-azimuth GoTo mount, a manual equatorial mount, an equatorial with RA drive, a GoTo equatorial, or a heavy GoTo equatorial suitable for imaging later.  YOUR CHOICE.

The choice of new mounts under £200 that are worth buying is somewhat limited.  If you can find one, a steel-tripod AZ-4 would make a simple and sturdy grab'n go mount.  Or consider an EQ-5,  available new or used as manual or GoTo and with upgrade kits readily available. This is a mount that is good for use with all sorts of smaller telescopes up to a 203mm f5 newtonian.

[jonathan]

2 minutes ago, Cosmic Geoff said:

The choice of new mounts under £200 that are worth buying is somewhat limited.  If you can find one, a steel-tripod AZ-4 would make a simple and sturdy grab'n go mount.  Or consider an EQ-5,  available new or used as manual or GoTo and with upgrade kits readily available. This is a mount that is good for use with all sorts of smaller telescopes up to a 203mm f5 newtonian.

I use my 150P reflector on a CG4 EQ mount (with 1.75" steel tube tripod legs), works fine.  A 130 OTA shouldn't tax an EQ3-2 mount at all IMO.  EQ5 I feel is overkill, unless it comes down to the width of the fitted dovetail bar (probably could be replaced with one to fit an EQ3-2).  Heck, even my 8" SCT fits the CG4 mount, it's seriously overloaded so I don't use it on there but the dovetail does fit.  Makes me wonder what a 'CG5' dovetail actually is.

[Cosmic Geoff]

I am suggesting the EQ-5 because with its 9Kg (visual) load capacity and choice of drives it offers more flexibility and future-proofing than a smaller mount.  It will definitely accept the size of dovetail used with the SLT mount. As will the EQ3-2 and the AZ-4, etc.

[Ricochet]

10 hours ago, Nargos_1 said:

I just want a stable mechanical mount

Assuming by mechanical you mean a manual, rather than goto, mount, I would be looking at the following alt-az options. You won't want to use an equatorial mount as that will rotate the eyepiece of a Newtonian and the SLT has the dovetail bolted directly to the tube so you cannot even rotate it in the tube rings to counteract this (unless you also invest in rings).

Skywatcher AZ4

Skywatcher AZ5

Scopetech Zero

The AZ5 and Zero mounts will also require the purchase of a separate tripod with 3/8" photo threads. A good quality Gitzo or Manfrotto carbon fibre tripod would be my choice for compactness in storage/transport, or a Berlebach wooden tripod if you want top dampening and don't need as much compactness. All of these are expensive though and the AZ4 is the most cost effective option.

[Nargos_1]

Thank you all, that was hugly helpfull. I ended up going for the Sky-Watcher EQ3-2 and hopefully will have a working teliscope again soon!