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Old 13-02-2020, 09:25 AM
RugbyRene (Rene)
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Edge HD 8" vs 9.25" - which one for galaxy season?

Hi,

I'm looking to get ready for galaxy season and am looking at getting a new SCT. Done a bit of research and have settled on either the Celestron Edge HD 8" or 9.25".

Aside from the size is there any feature the 9.25 has over the 8 that would justify the almost $2000 extra cost?

Rene
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Old 13-02-2020, 11:49 AM
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fornax (Phil)
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galaxy hunting needs aperture ... that's it
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Old 13-02-2020, 12:25 PM
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MortonH
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The 9.25" doesn't really go that much deeper than 8" but is physically quite a big bigger (and a lot more expensive).

I'm waiting for someone to suggest a big Dob for less money!
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Old 13-02-2020, 07:32 PM
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Ukastronomer (Jeremy)
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I chose the 8" for one reason, portability, the other is much larger and heavier

I have also used both and side by side before buying and no viewing difference, after all it isn't as though you are discussing 8" v 15"
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Old 13-02-2020, 07:35 PM
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Ukastronomer (Jeremy)
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Quote:
Originally Posted by MortonH View Post
The 9.25" doesn't really go that much deeper than 8" but is physically quite a big bigger (and a lot more expensive).

I'm waiting for someone to suggest a big Dob for less money!
Horses for courses, why a dob, refractors do some things better than scts, scts do some things better than refractors, reflecting scopes do some ...........

I am a Moon person so would not want a reflecting scope (Dob) hence my APO
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Old 14-02-2020, 03:09 PM
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Camelopardalis (Dunk)
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Given that most galaxies are quite small, you might want to consider whether the Edge HD is a must-have. Are you looking for a visual scope only or an imaging-capable scope? The field curvature of the standard SCT would not be intrusive for visual, with most eyes and galaxies.

FWIW, the non-Edge HD 11" SCT is lower priced than the 9.25" Edge HD scope. Either would happily ride on your AZ-EQ6.

Imaging might open a whole new kettle of fish...
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Old 14-02-2020, 06:28 PM
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Given that most galaxies are quite small, you might want to consider whether the Edge HD is a must-have. Are you looking for a visual scope only or an imaging-capable scope? The field curvature of the standard SCT would not be intrusive for visual, with most eyes and galaxies.

FWIW, the non-Edge HD 11" SCT is lower priced than the 9.25" Edge HD scope. Either would happily ride on your AZ-EQ6.

Imaging might open a whole new kettle of fish...
Of course the Edge HD was designed and built for imaging



.
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Old 14-02-2020, 06:55 PM
Rainmaker (Matt)
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Quote:
Originally Posted by Ukastronomer View Post
Horses for courses, why a dob, refractors do some things better than scts, scts do some things better than refractors, reflecting scopes do some ...........

I am a Moon person so would not want a reflecting scope (Dob) hence my APO
Curious about this statement, I have a very fine Apo but for sheer detail it simply cannot compete with the resolving capacity of my reflector..... looking at some features at 500x + on a good night

as for galaxies a used C11 over a C8/C9.25 Edge any day !!
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Old 14-02-2020, 08:32 PM
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Curious about this statement, I have a very fine Apo but for sheer detail it simply cannot compete with the resolving capacity of my reflector..... looking at some features at 500x + on a good night

as for galaxies a used C11 over a C8/C9.25 Edge any day !!
It is a fact that the central obstruction results in degraded contrast from reflecting/sct scopes etc as compared to a refractor, pure Physics

I have all three and the triplet is best
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Old 14-02-2020, 08:36 PM
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Quote:
Originally Posted by RugbyRene View Post
Hi,

I'm looking to get ready for galaxy season and am looking at getting a new SCT. Done a bit of research and have settled on either the Celestron Edge HD 8" or 9.25".

Aside from the size is there any feature the 9.25 has over the 8 that would justify the almost $2000 extra cost?

Rene
you don't ask about portability I assume you have an observatory ?


.
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Old 15-02-2020, 07:11 AM
N1 (Mirko)
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Quote:
Originally Posted by Ukastronomer View Post
It is a fact that the central obstruction results in degraded contrast from reflecting/sct scopes etc as compared to a refractor, pure Physics
Depends on one's observing goals. For pure image quality at a given aperture, nothing touches an unobstructed optic. Period. However it's easy for other designs to be made big enough so that this disadvantage is more than compensated for through brighter images and higher resolution.
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Old 15-02-2020, 12:39 PM
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Atmos (Colin)
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Quote:
Originally Posted by Ukastronomer View Post
It is a fact that the central obstruction results in degraded contrast from reflecting/sct scopes etc as compared to a refractor, pure Physics

I have all three and the triplet is best
The contrast of galaxies visually is largely from the amount of photons your eyes can see. This is how aperture trumps unobstructed.
A 16 RC with a 50% obstruction will still leave a 4-5 APO for dead for contrast.
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Old 15-02-2020, 01:49 PM
Zuts
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Quote:
Originally Posted by Ukastronomer View Post
It is a fact that the central obstruction results in degraded contrast from reflecting/sct scopes etc as compared to a refractor, pure Physics

I have all three and the triplet is best
Not sure how stars you can resolve in a galaxy, I would go for a bit brighter image.
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