Sky Watcher 72ED as a guide scope

[edlaw3]

Hello Everyone!

I've loved astronomy since the 70s but only recently (2019) has it become a hobby.  I am starting to do astrophotography and have already captured some images of the Orion Nebula.  I am using the following equipment: Sky Watcher 120ED, Meade LX-85 EQ mount and a Canon 60D (unmodified).  I want to add a guide scope and camera but am unsure what to get.  I have my eye on a Sky Watcher 72ED.

Is this a good choice or is it overkill?

[rl]

It will doubtless do a very good job as a guidescope but yes, it is overkill in terms of optical quality. A lot of people make do with a cheap achro 80mm for 50 quid secondhand. Whatever you choose does need to have a sturdy focuser and attachment to the main scope. Some people reckon a  slightly soft focus can be an advantage in making the centroid of the star image easier for PHD to calculate

It's not quite as overkill as my Pentax 75 SDHF which was used solely as a guidescope for years by its previous owner...

A 72ED would double up as an excellent travel scope. 

Edited April 30, 2020 by rl
spelling

[Robindonne]

I like that way of thinking.  Also want to use a 71 mm apo for guiding an 8” sct.  If the mount can handle the weight and you can double use the small apo now and then, why buy a single purpose mini refractor for guiding? Most of them cost the same as a used small apo. And for backup buy a small oag adapter when using the small apo as main scope

[Skipper Billy]

I use a 72ED for guiding along with a Lodestar - works superbly.

Important to have the right imaging / guiding ratio - there is a very good calculator here - http://astronomy.tools/calculators/guidescope_suitability

 

[Louis D]

I wonder how well the new crop of low cost, Chinese 50mm and 60mm finder scopes with helical focusers work for guide scopes.  Anyone tried one?

[edlaw3]

On 30/04/2020 at 11:50, rl said:

A 72ED would double up as an excellent travel scope. 

This is one of the reasons that I was looking at this scope.  It can be dual purpose.

[edlaw3]

On 30/04/2020 at 13:41, Robindonne said:

I like that way of thinking.  Also want to use a 71 mm apo for guiding an 8” sct.  If the mount can handle the weight and you can double use the small apo now and then, why buy a single purpose mini refractor for guiding? Most of them cost the same as a used small apo. And for backup buy a small oag adapter when using the small apo as main scope

I have an LX85 mount. While it isn't the best by any means, it was budget friendly and has a 33 lb. capacity.  With the addition of the 72ED, I will be at 66% capacity.

[TerryMcK]

You might even find that this works fine for your gear - it would be fine for the 120ED too.

Sky-Watcher 9x50 Finder & ZWO ASI120MM-Mini Bundle https://www.firstlightoptics.com/guide-scopes/sky-watcher-9x50-finder-adapter-zwo-asi120mm-bundle.html

I am using the same setup albeit I came from already having an existing finderscope. The whole rig is fairly lightweight and you don't actually need the bracket if you have rings. 

[edlaw3]

On 30/04/2020 at 13:50, Skipper Billy said:

I use a 72ED for guiding along with a Lodestar - works superbly.

Important to have the right imaging / guiding ratio - there is a very good calculator here - http://astronomy.tools/calculators/guidescope_suitability

First off, I am in awe of your setup and the images that you have captured!  I really like your image of Markarian's Chain.  Great job!

I'm considering pairing the 72ED with a ZWO ASI120MM camera.

[TerryMcK]

Just another thought the 72ED is great for wider field work (thinking nebula etc) so if you have a separate 50mm guide scope it would mean you can use it for that too. Otherwise it is an OAG attachment. Either way its going to cost .