On Tuesday, July 19, 2016 at 2:33:21 PM UTC-4, StarDust wrote:
On Tuesday, July 19, 2016 at 11:25:14 AM UTC-7, Chris L Peterson wrote:
On Tue, 19 Jul 2016 11:08:43 -0700 (PDT),
wrote:

I've seen some images with SCT, because the large CO, the stars look very bloated.

No. A large CO does not produce bloated stars. It was either a scope
with poor optics, it was the result of poor collimation (very common
with SCTs), or some other factor.

Well, my C 11 SCT, does have a large airy disk around stars for sure!
More magnified the more it shows.
So, you don't think a camera would record that?

The physical size of the Airy disk is determined by the focal ratio of
the telescope, and the resulting apparent size by the magnification
(or the pixel scale in the case of imaging). The central obstruction
doesn't change that. A large central obstruction does place a little
more energy into the outer rings, but it's unlikely that's really
going to make the stars look bigger (and it would certainly be very
subtle). When imaging, we almost never see diffraction rings around
stars at all, because seeing is the dominant factor in reducing
resolution.

Nearly all professional telescopes use RC optics these days, which
have very large obstructions. Resolution is not impacted, and for
imaging the effect on the MTF is generally very minor compared with
the other advantages of the design.

Well, in my 4" apo f/8.9 I have to look for any the airy disk, in my C-11 f/10 33% OC, pokes my eye out.
Maybe you should read Suiter's book, Star Testing Astronomical Telescopes.

Then there must be something wrong with your larger scope, or else you are overlooking some other factor(s). Compare the scopes side-by-side on a night when both can perform at their best, use the same mag with each and control all possible variables. Then get back to us.