Which scope?

[andyk74]

Hi all,

  I am considering buying a second telescope to use mainly for planetary/lunar imaging but also capable on DSO’s. I currently have a SW 150PDS mounted on a SW AZEQ6GT mount.

  I am looking for a scope that would allow greater focal length than my current 150PDS that I can use for detailed lunar and planetary imaging, but, one that can also be used for some DSO work. My budget is up to £1200.

  Having spent many hours looking at various scopes I have narrowed it down to the following:

1.       Vixen VC200L VISAC

2.       Altair Astro 8” RC Carbon

3.       Celestron Edge 800 HD

I understand that the Vixen and Altair scopes are less prone to dewing than the Celestron, however, looking through the posts on here, the quality and set-up of the Altair can be hit and miss. The Celestron has a longer focal length and should be better for planetary (?) but has a reduced FOV over the other two.

[andrew s]

If the optics of your SW 150PDS are good why not just add a quality extender like a TelVue Powermate? Or, if they are not so hot, get an Orion Optics ultra grade mirror set for use in the existing tube again with a powermate?

Regards Andrew

[ChrisLX200]

On what mount? For planetary imaging it's not too demanding a task, but for DSO (and consequent longer exposures) it is critical your mount can handle it. Personally I would go for an RC - perhaps a larger aperture than 8" if you can (say, 10"). The difference between a 5" Newt and 8" CAT/RC is not going to be huge...

ChrisH

[andyk74]

Chris,

Skywatcher AZ-EQ6GT mount

[andyk74]

Andrew S, never considered changing the mirrors. How much difference would that make?

 

[cs1cjc]

For a fee, Orion UK would be happy to test your mirror, see: Orion_UK_Optical_Testing.

You might be able to negotiate a deal if there is the prospect of the sale of a new high specification mirror...

[andrew s]

1 hour ago, andyk74 said:

Andrew S, never considered changing the mirrors. How much difference would that make?

 

It depends on how good or not the current optics are. However, in my view a Newtonian with a powermate is as good as anything for planetary unless you go for specialised optics which would not be good for DSO. 

I had not noticed you has  5" Newt as I don't think OO have this size.

I agree with the point above about the need for a good mount for imaging. Personally I have always gone for the best mount I could afford followed by good optics and DIYed as much as the rest as possible the other exception being a good focuser.

Regards Andrew 

[andyk74]

I have a 6" Skywatcher reflector and AZ-EQ6GT mount, also by Skywatcher. I have the standard 2x barlow that came with the scope and purchased a 3x barlow:

http://www.365astronomy.com/SkyWatcher-X3-Barlow-Lens-4-Element.html

however, I have been a bit disappointed with the results. I just think that a longer native focal length telescope would produce better images than a shorter focal length using a Barlow. 

[andrew s]

33 minutes ago, andyk74 said:

I have a 6" Skywatcher reflector and AZ-EQ6GT mount, also by Skywatcher. I have the standard 2x barlow that came with the scope and purchased a 3x barlow:

http://www.365astronomy.com/SkyWatcher-X3-Barlow-Lens-4-Element.html

however, I have been a bit disappointed with the results. I just think that a longer native focal length telescope would produce better images than a shorter focal length using a Barlow. 

What you have to remember is that unless you go for a long focus refractor or Newtonian your "native focal length" telescope will have  a shorter focal length element plus an amplifying lenses or mirror (or possibly both) the views will ultimately depend on the quality of the optics. Long focus refractors and Newtonians are the simplest to make well but are not, in general, good for DSO imaging.

By the way Powermates are in a different league to standard Barlows.

You will have to compromise somewhere.

Regards Andrew

[andyk74]

Ok, makes sense, thanks for the advice, looks like I will invest in a Powermate!