grab and go OTA for AZ4

[vegaandarctures]

Looking for an OTA for my az4 mount (aluminium legs). Its main purpose will be lovely wide field views to complement my 8inch dob. I originally had my eye on one of those short tube skywatcher achromats. Either the 80 or the 102, although I've never looked through one. 

Although I am somewhat tempted by something like a 130PDS, would something like this be of higher quality than the achromats? I'd appreciate your opinions on what choice I should make.

Clear skies,

Thomas 

[happy-kat]

If wide field then wouldn't the star travels be wider and you'd only get chromatic aberration on the really bright stuff, I'm happy with what I see in the ST80 as the stars look great and different from the heritage 130p.

[vlaiv]

Only issue I've found with short refractors on this mount is observing near zenith. I had ST102 and TS80 F/6 apo mounted on AZ4 and both would sort of hit the mount with focuser knobs when looking straight up.

If that is concern to you  - check how would 130mm tube fit that mount by using some sort of mock up (there is a chance you would not be able to look at zenith targets with wider OTA as it would hit the mount head).

This image illustrates potential problem - just imagine OTA pointing straight up - it would definitively hit mount base.

[vegaandarctures]

Thanks for your replies, I was using a 127mm Mak on this mount and it was no problem. I'm kind of leaning towards an ST80.. but I don't know..

I've heard good things about them, but then I've heard not so good things. If it will provide bright, crisp wide field views then it will satisfy me. I wish I could look through one before I buy really

[vlaiv]

1 hour ago, vegaandarctures said:

I wish I could look through one before I buy really

You seem to have 15x70 binoculars?

That is not far away from ST80 experience.

You'll be able to change magnification but only use one eye for observing. Image will be slightly brighter but not by much. It should also be sharper and depending on eyepiece used - larger AFOV.

[cloudsweeper]

My Bresser AR 102S (short focus) is a fine, light, grab'n'go OTA on the AZ4, giving very wide views and mag easily up to x200.  AND....it has a very nice focuser.  The Startravel focuser is nowhere near as smooth.

Also - a frac would give crisper views.  A Newt only has a big advantage when you get up 8 or 10 inches, and you have an 8" Dob anyway.

Doug.

Edited October 14, 2020 by cloudsweeper

[John]

I've used my Vixen ED102SS F/6.5 on an AZ-4 mount. Very nice combination and compliments an 8 inch dob perfectly. So I'd recommend something like an ED 102 F/6-7 ish refractor. (the Vixen I have is long out of production).

 

Edited October 14, 2020 by John

[Stu]

I agree with John! A lot depends on budget of course, but an f7 ish 4” apo is an excellent complement to a larger dob.

[Alkaid]

The Startravels are really nice for sky sweeping at low power visual use.  Up to 120 size sit well on an AZ4, vibration not a problem at low powers.   No real problems with CA at low power on star fields, Messier objects are quite reasonable at dark sky sites.

Starfields and deep sky is where these scopes lie, and only for visual.  But nothing else...

If you have the pennies, get the APO...

Edited October 16, 2020 by Alkaid