Maksutov-Cass versus Newtonian

If I were in your shoes, I'd be thinking aperture!!

I've settled on a minimum of 14" with a preference for 16" and if at all possible, larger. But within price limits of course...

It seems the only designs of this size are really the Mak-Cass or Klev-Cass, Newtonian, RC or modified RC (or other derivatives).

The Wynne Corrector seems to be touted as a better version of the Paracorr and derivatives. With a price to match its perfomance... :roll:

Thanks again for the comments - very useful. Keep them coming!

Dave

dave it crossed my mind that edge of field definition might be more important for positional astrometry than you might think at first thought. If you are using a star at the edge of the field to assist in measuring an asteroids position, then surely if this star had coma, the job becomes more complex?

Maybe I have this wrong but it that were true then maybe you'll need to start thinking about an RC or similar.

Good point Dave but the latest astrometric software packages reject any comparison stars that are clearly not where they should be. Also, one of the packages I use actually lets you pick and choose the comparison stars so I could alwys do some visual quality control. The same goes for photometry.

If I get a 16" F5 Newt and couple it the E2V back illuminated chip, I get a field of view a tad smaller than a full Moon - about 24 arcmins square. I've been working my astrometry on about 12 arcmins square with 'professional' results. I'd be working with 4 times that so can afford to lose some of the ojects at the edge. Of course, I'd prefer not too, but an 16" RC is really out of my price league...

I have to say that this even more of a tricky decision than I thought. The CCD on its own was fairly hard, the OTA harder. And then you have to match the pair... :roll:

But these discussions are very helpful and its always great to get the feedback from you guys. Hopefully I'll get there soon enough...

Cheers

Dave

Hi,
I have a 6" mak cass (intes mk67) and I can say they are fine scopes, they have good optics, here are the pros and cons I found with it.

Pros
Excellent optics, one fo the best scope I've ever seen through.
Very robust, looks like it could survive deen dropped down the stairs.
The model I have has a fixed primary mirror, no image shift.
The primary and secondary are both collimatable (actually not typical in mak cas scopes)

Cons
Narrow field fo view in photography, more vignetting then you get in a SCT.
This is a heavy scope, much heavier then an average 6" scope
Collimating it makes collimating a SCT look very simple, but once there it holds it very well.
Cooling times might be a problem if it was to be carried in and out of a house.
A newtonian of similar aperture is much cheaper to buy.
Low focal ratios are hard to come by (typical f10-f18).

Over all a fine little scope, more suited to planetary work and not wide field astrophotography.

Nice one Dave - very succint.

I think the cost of the larger Maks rules them out in the absence of a lottery win unless I can scrape enough for the 14" which might be attainable. But for about the same price I can get the 20" Newt. The 16" Newt is affordable as is...

Cheers

Dave

What you want is a light bucket, so that means a newtonian me thinks.