Re: tak quality SCT?
- From: RichA <none@xxxxxxxx>
- Date: Sat, 14 May 2005 00:06:34 -0400
On Fri, 13 May 2005 18:14:56 -0600, mmd49@xxxxxxxxx (Mark D) wrote:
>I looked through an AP Mak Cas once.
>Maybe it was just me, but I was far more impressed at the AP 1200 mount
>than the OTA.......
>Allan
>---------------------------------------------------------------
>Perhaps so, especially, if you were at a star party, and just before
>looking through the AP Mak, you looked through a 20" Dob?
>
>I'll admit, I've seen this once too, at one Astrofest, just coming from
>a friend's Compustar 14, and then looking through the AP 10" Mak
>(Roland's own personal scope, perhaps the Prototype)
>
>Yes, I'm sure I saw a little more nebulosity in the C-14 lookng at DSO's
>such as the Lagoon, and Trifid nebulas vs the AP 10" Mak, but I also did
>regognize too, the much tighter star images, and high contrast that was
>at hand through the AP.
>The differences were subtle, and after running back, and forth a few
>times, you begin to recognize the quality of the AP Mak. Individual
>stars did appear a bit more "bloated" through the C-14. For visual use,
>this may not seem quite so important, but for imaging, I'm sure this
>makes all the difference in the world.
But that doesn't prove anything unless you can say for sure
that the images of the stars you saw were diffraction limited and
that they were truly "bloated" beyond the normal diffraction pattern,
something that you are unlikely to see in a modern SCT. More likely
what you saw was the effects of seeing or cooldown or both, on a much
larger instrument. Reason being the diffraction images in the
c14 would be much smaller than those in a 10" scope. If you were
using both scopes at powers lower than those that would allow you
to see the actual diffraction disc and rings, then you can't really
say that they were bloated in the c14 because of optical issues
because it's not possible unless you satisfy the other criteria first.
You'd never compare two top flight refractors to each other unless
seeing conditions were superb and both instruments at thermal
equilibrium because it would be a waste of time.
IF the seeing was very good, IF both scopes were fully cooled down
and IF you were using powers high enough, then you could pronounce one
better than the other. As for contrast, that would depend on coatings
and surface quality of each optic so if you saw better contrast in the
AP, it could mean those optics were better than the C14s.
Personally, I've compared excellent (best scope ever was an AP 180)
scopes with lesser ones and the lesser ones have to be substantially
"less" to lose on deepsky objects IF they have considerably larger
optics. The differences between the very best scopes and the best
mass-produced scopes simply are no longer great enough to allow this.
-Rich
.
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