Using a 90mm spotting scope, choosing a mount for it

[Francis King]

Hello.

I am looking at buying a compact telescope for Moon / planets. My budget is about £200, which doesn't provide much wriggle room. I could get a 90mm long-barrelled refractor or reflector on an EQ/2, an AZ3, or something like that. I have read reviews that say that this size of mount is somewhat overwhelmed by the telescope. I can buy a short-barrelled refractor or reflector, but the design isn't designed for Moon / planets.

What I need is a system which can be moved and stored easily. I had a 200mm Dobsonian reflector, which was too big to move and store, and so I got rid of it.

What I do have is my trusty old Catadioptric terrestrial spotting scope, 90mm aperture, 1200mm focal length, erect diagonal. With a 32mm eyepiece, so about x40 fixed magnification. It's fully functional as a spotting scope.

I am considering putting the spotting scope on an astronomical tripod - it's really an astronomy telescope after all, just rebadged as a spotting scope anyway. Then I can spend the entire budget on a nicer mount.

Your advice, please.

Would my plan work?

Would I be better off with an equatorial mount (currently my inclination) or an alt-az mount?

Would I need additional components to make my spotting scope work as a telescope?

Thanks,

Francis.

[happy-kat]

Hi, can your spotting scope take a different diagonal, only your current one might be 45 degrees angle and for astro use you would likely find a 90 degree diagonal more comfortable to observe with.

If you already have a phot tripod or similar you use it on you might find with a camera ball head you could use it for astro use as a altaz mount. 

[Francis King]

50 minutes ago, happy-kat said:

Hi, can your spotting scope take a different diagonal, only your current one might be 45 degrees angle and for astro use you would likely find a 90 degree diagonal more comfortable to observe with.

Thanks for your comments.

The actual spotting scope is this one: C90 MAK. The whole thing is composed of many parts, so I can replace the diagonal with a new one.

 

54 minutes ago, happy-kat said:

If you already have a phot tripod or similar you use it on you might find with a camera ball head you could use it for astro use as a altaz mount. 

Yes, that's a good point. I have a fairly substantial RSPB tripod. But it doesn't have slow-movement controls.

[happy-kat]

maybe the tripod legs have a base plate onto which you could mount a tripod head like this perhaps

https://www.firstlightoptics.com/sky-watcher-az5-deluxe/sky-watcher-az5-deluxe-alt-azimuth-mount.html

[Louis D]

You'll definitely want a side mounted alt-az for visual use, as long as you don't mind manual tracking.  I've tried using a fluid head on a photographic tripod for astronomy with an ST80, but beyond a certain point vertically, the telescope tips back uncontrollably.

[Stu1smartcookie]

Coming at this from a slightly different angle , as you have a scope , and a tripod ... buy an AZ-GTi and you can track the moon and planets without worrying about slow motion controls ... the scope is light enough and ii'm sure your tripod will suffice for now . The only problem i see is the AZ-GTi is a liitle over budget , but ... thats what happens in this hobby 

Stu

 

[Louis D]

And the AZ-GTi has a Point and Track mode that doesn't require prior alignment if goto is not needed (as for bright solar system and DSO objects) and the mount is well leveled.  That alone sounds very useful for high power observing.

Alignment of my Dob's DSCs can be an issue for me due to the narrow swath of sky I can see from my backyard.  I use the app SkEye to get me in the ballpark of dim objects since it relies solely on internal sensors.  It gets me close enough to know if the object is even visible at that time for me.

[Geoff Lister]

I have a 90mm Mak as an integral part of my Heritage 90p Virtuoso system; and the OTA has a side-mounted dovetail rail, an RDF, and a 90 degree diagonal. I also have a C90 spotting Mak; which has a bottom-mounted rail, a dinky finder scope (works better in sunlight) and a 45 degree diagonal.

With a swap of diagonals, the spotting Mak fits on most of my mounts (see my signature), but the finder would be in the lower-left quadrant (upper right on the iOptron Cube). Even with a 32mm Plossl eyepiece, the minimum magnification of about x40 is a bit high for bird-watching. The Travescope 70 (refractor), with its 400mm FL, is much easier to use for bird-watching.

The Virtuoso mount, with its built-in tracking (or full GoTo if I borrow the Synscan handset from my Skyliner), is, given the Mak's long FL, much easier to use than a simple tripod.

Geoff