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C9.25 XLT?

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#1 spiral

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Posted 16 January 2015 - 02:08 PM

Ok, its well known around the forums that by design,  the 9.25 XLT has a little flatter field and less coma..BUT, how does it compare to the 800 Edge's flat field? Would you buy the 800 Edge over the 9.25 XLT or go for the extra aperture?


Edited by spiral, 16 January 2015 - 02:09 PM.


#2 junomike

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Posted 16 January 2015 - 02:24 PM

Ok, its well known around the forums that by design,  the 9.25 XLT has a little flatter field and less coma..BUT, how does it compare to the 800 Edge's flat field? Would you buy the 800 Edge over the 9.25 XLT or go for the extra aperture?

Tough call.  I've viewed through a C9.25 XLT and really liked it, but I also really like my 8" EdgeHD with the Tempest cooling fans.

If you're located in a warmer climate and view DSO's then the C9.25 is probably the better choice, but If you're in the frozen tundra and view mostly Planetary.Lunar then I

think the faster cooling EdgeHD (with fans) would be the way to go.

 

Mike


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#3 AL W

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Posted 16 January 2015 - 09:50 PM

The extra bit of aperture in the 9.25 XLT "may" help you see some color in Jupiter's bands. But, never looked thru this scope, per se.

 

I had a C9.25 EdgeHD and a C8EdgeHD. The "9" was a handful putting up on the CG-5GT mount, but views of the moon were extrodinary, so the XLT might be similar.

 

I did end up using the C8 EdgeHD more than the C9.25 mostly because of the weight issue.

 

Viewing thru the C8 EdgeHD, well, the stars were all pinpoint right to the edge! :) Simply stunning!



#4 ur7x

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Posted 16 January 2015 - 09:55 PM

As the owner of a 925XLT, if I were to do it all again, I would probably buy the 8" HD,  but not because of coma or field flatness or the vents... No, that is the largest scope that you can fit in an overhead bin for a flight to a dark site.   And the HD scopes hold their resale value better.

 

Only you can tell which will work best for you... I have looked through both a 925 HD and a 925 XLT on the same night at the same target.  Visually (or even prime focus photography) I could not tell a difference between the two scopes. Lots report a difference, just as many can't tell.  Only you can tell.


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#5 mark379

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Posted 17 January 2015 - 01:22 PM

Ok, its well known around the forums that by design,  the 9.25 XLT has a little flatter field and less coma..BUT, how does it compare to the 800 Edge's flat field? Would you buy the 800 Edge over the 9.25 XLT or go for the extra aperture?

 

I owned both at the very same time and did an extensive comparison visually. You may view the thread here:

 

http://www.cloudynig...ide-comparison/

 

 

it's hard to say. Both are very good. Depends on if you use Widefield 100° eyepieces or not. On 82° Ep's such as a TV 31 Nagler, the 9.25 comes very close, and on nights of good seeing definitely and significantly outperforms the eighton both planets and deep sky resolution of objects such as globular cluster,s etc. On planetary nebula, it is not as apparent of a difference. 

The eight  edge is excellent ,and yes more portable. 

As far as deep sky photography is concerned, the eight hd might have a slight edge over the 9.25 standard, Though On  planetary imaging I would say the opposite.

 

have a look at the thread. I hope you find it useful. 

 

Best

Mark


Edited by mark379, 17 January 2015 - 01:23 PM.

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#6 Bill Barlow

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Posted 17 January 2015 - 05:39 PM

I agree with the previous member comments.  I have never observed with an Edge scope, but have previously owned both a standard C8 and C9.25.  I would say it comes down to weight and portability..how much scope do you want to set up/carry around on whatever mount you own.   The 9.25 will give a slight increase in image brightness and resolution, but not a "wow" increase.  Knowing what I know now, I like the most aperture I can get/handle, so I would opt for the 9.25.  Good luck!

 

Bill


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#7 jrbarnett

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Posted 20 January 2015 - 10:19 PM

I had a C8.  I now have a C9.25 Edge HD.  Were I to do it all over again, I'd get a standard C9.25.  The extra 1.25" is nice.  The Edge flatness for visual, not so much of boon as to warrant almost double the price (above 8", that is - the 8" Edge has a much smaller premium over the non-edge version).

 

- Jim


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#8 Patrick

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Posted 20 January 2015 - 11:51 PM

Ok, its well known around the forums that by design,  the 9.25 XLT has a little flatter field and less coma..BUT, how does it compare to the 800 Edge's flat field? Would you buy the 800 Edge over the 9.25 XLT or go for the extra aperture?

 

The best way to compare the standard C9.25 vs the Edge optically is to look at the spot diagrams.  Celestron gives those spot diagrams in it's White Paper HERE.  On page 5 you can see the difference in star shape out to about 20mm off center.  Just for reference, the largest diameter 1.25" eyepiece is going to be about 27mm in diameter (13.5mm center to edge).

 

I've considered the C9.25 many times but that size never made sense to me since the C11 is only a couple of inches longer and weighs only 7 lbs more than the C9.25.  Moving up to the C9.25 or C11 is going to take more effort either way.

 

With Panoptic eyepieces (68° AFOV), the views through a standard SCT can be quite spectacular.   Panoptic (or equivalent AFOV) eyepieces limit the damage at the edges of the FOV making the standard SCT much more pleasant to use.

 

I personally don't give much credence to the 9.25 vs 11 or 8 mystic, so that's not a factor for me.

 

As far as your choice is concerned, it guess it depends. I personally like the Edge optics because I don't have to place the object I'm looking at dead center in the FOV to get a clean view.  The Trap in Orion looks just as good off center a bit as it does on center with the Edge.  With the standard SCT, it's more important to keep your object near the center of the FOV. 

 

Patrick


Edited by Patrick, 20 January 2015 - 11:57 PM.

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#9 abaum

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Posted 21 January 2015 - 06:43 PM

I had to make the same decision back in November.  Went with the C9.25 XLT since I am a visual observer.  For cooling, I bought an aftermarket fan.  So far, I have been generally happy.  The only unhappiness so far is that I have learned how bad seeing conditions affect these larger scopes more so than compared to my 3" refractor. 

 

adam


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#10 Bill Barlow

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Posted 21 January 2015 - 08:25 PM

Very true, Adam.

 

Bill



#11 jrbarnett

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Posted 16 January 2017 - 04:50 PM

For visual use, here is the fallacy of the Edge HD design..."I don't like to have to center objects to get good views so I went Edge".

 

SCTs have itty, bitty FOVs.  The difference between centered or not in even a low power eyepiece is almost trivial.  It's not like a refractor where your 31mm Nagler is working with a 3+ degree FOV.  You'll generally be operating with under a degree FOV.  An object at the edge of the field is a whisker from the center; centering adds little extra effort on the user's part.  Perhaps if you used your SCT on an undriven alt-az mount it'd matter, but few use big SCTs on undriven mounts.

 

Regards,

 

Jim


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#12 doctordub

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Posted 20 January 2017 - 08:48 AM

For visual use, here is the fallacy of the Edge HD design..."I don't like to have to center objects to get good views so I went Edge".

 

SCTs have itty, bitty FOVs.  The difference between centered or not in even a low power eyepiece is almost trivial.  It's not like a refractor where your 31mm Nagler is working with a 3+ degree FOV.  You'll generally be operating with under a degree FOV.  An object at the edge of the field is a whisker from the center; centering adds little extra effort on the user's part.  Perhaps if you used your SCT on an undriven alt-az mount it'd matter, but few use big SCTs on undriven mounts.

 

Regards,

 

Jim

The few, the proud, the undriven.

CS

Jonathan

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#13 clusterbuster

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Posted 23 January 2017 - 11:09 AM

20170119_132724-1.jpg My C9.25 has the best optics that I have ever owned (40+ yrs)...

It is on a SkyView Pro Go To Mount.

I use the vibration pads also.. It works fine..It's all about balance.Although I would like to put it on a CGEM when my funds allow.  This is a FINE TELESCOPE indeed.

Mark


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#14 MrJones

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Posted 23 January 2017 - 11:25 AM

I'd get a Meade 10" ACF if they go down to $1500 again.



#15 junomike

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Posted 23 January 2017 - 01:18 PM

I'd get a Meade 10" ACF if they go down to $1500 again.

They were that low before?

 

Mike



#16 Cpk133

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Posted 23 January 2017 - 06:26 PM

attachicon.gif20170119_132724-1.jpgMy C9.25 has the best optics that I have ever owned (40+ yrs)...

It is on a SkyView Pro Go To Mount.

I use the vibration pads also.. It works fine..It's all about balance.Although I would like to put it on a CGEM when my funds allow.  This is a FINE TELESCOPE indeed.

Mark

Uh hum, Big Dog?


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#17 MrJones

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Posted 24 January 2017 - 10:49 AM

 

I'd get a Meade 10" ACF if they go down to $1500 again.

They were that low before?

 

Mike

 

Yes, early last year for a couple of months.



#18 clusterbuster

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Posted 25 January 2017 - 03:51 AM

I USED TO HAVE A MEADE 10 ACF,

THIS C 9.25 has much better optics, Stars are Refractor like and Planetary is better than the 10 ACF and I am a METICULOUS collimator, That is why he is the BIG DOG !

Mark

 

Check out the

C 9.25 vs Meade 10 ACF

C 9.25 vs Meade 7 Mak    and

C 9.25 vs C 11 

threads.. 

My experience reflects many of the comments on those threads.

The C 9.25 is Unique in its design !!!


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#19 Cpk133

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Posted 25 January 2017 - 08:12 AM

I USED TO HAVE A MEADE 10 ACF,

THIS C 9.25 has much better optics, Stars are Refractor like and Planetary is better than the 10 ACF and I am a METICULOUS collimator, That is why he is the BIG DOG !

Mark

 

Check out the

C 9.25 vs Meade 10 ACF

C 9.25 vs Meade 7 Mak    and

C 9.25 vs C 11 

threads.. 

My experience reflects many of the comments on those threads.

The C 9.25 is Unique in its design !!!

I was wondering if you were being sarcastic because it is a cat after all.


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#20 clusterbuster

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Posted 25 January 2017 - 11:16 AM

No, not sarcastic, but the C 9.25 is different than regular Cats, so I dubbed it Big Dog !!!

Mark



#21 jrbarnett

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Posted 25 January 2017 - 04:03 PM

 

For visual use, here is the fallacy of the Edge HD design..."I don't like to have to center objects to get good views so I went Edge".

 

SCTs have itty, bitty FOVs.  The difference between centered or not in even a low power eyepiece is almost trivial.  It's not like a refractor where your 31mm Nagler is working with a 3+ degree FOV.  You'll generally be operating with under a degree FOV.  An object at the edge of the field is a whisker from the center; centering adds little extra effort on the user's part.  Perhaps if you used your SCT on an undriven alt-az mount it'd matter, but few use big SCTs on undriven mounts.

 

Regards,

 

Jim

The few, the proud, the undriven.

CS

Jonathan

 

I admire you.

 

One of my buddies, Reuben (CNer delgado39) also runs a C9.25 on an undriven mount.

 

I admire him too.

 

But you're both still crazy.  :grin:

 

- Jim



#22 jrbarnett

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Posted 25 January 2017 - 04:06 PM

attachicon.gif20170119_132724-1.jpgMy C9.25 has the best optics that I have ever owned (40+ yrs)...

It is on a SkyView Pro Go To Mount.

I use the vibration pads also.. It works fine..It's all about balance.Although I would like to put it on a CGEM when my funds allow.  This is a FINE TELESCOPE indeed.

Mark

BIG DOG (er, I meant "CAT")

 

:grin:

 

- Jim


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#23 jrbarnett

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Posted 20 June 2019 - 12:25 PM

The best way to compare the standard C9.25 vs the Edge optically is to look at the spot diagrams.  Celestron gives those spot diagrams in it's White Paper HERE.  On page 5 you can see the difference in star shape out to about 20mm off center.  Just for reference, the largest diameter 1.25" eyepiece is going to be about 27mm in diameter (13.5mm center to edge).

 

I've considered the C9.25 many times but that size never made sense to me since the C11 is only a couple of inches longer and weighs only 7 lbs more than the C9.25.  Moving up to the C9.25 or C11 is going to take more effort either way.

 

With Panoptic eyepieces (68° AFOV), the views through a standard SCT can be quite spectacular.   Panoptic (or equivalent AFOV) eyepieces limit the damage at the edges of the FOV making the standard SCT much more pleasant to use.

 

I personally don't give much credence to the 9.25 vs 11 or 8 mystic, so that's not a factor for me.

 

As far as your choice is concerned, it guess it depends. I personally like the Edge optics because I don't have to place the object I'm looking at dead center in the FOV to get a clean view.  The Trap in Orion looks just as good off center a bit as it does on center with the Edge.  With the standard SCT, it's more important to keep your object near the center of the FOV. 

 

Patrick

I'd like to resurrect this old thread and share some insights.

 

No mystique at all on the C9.25 vs. C11 vs. C8 standard SCT front.  It's simple math.  The C9.25 primary is f/2.3.  The C11 and C8 have f/2 primaries.  At those fast ratios, a 0.3 stop difference makes a material impact on uncorrected field flatness.  Credence isn't necessary when we have science.  :grin:

 

And be careful with the spot diagrams in the white paper.  The don't specify what aperture SCT they used to get those spots, but it cannot have been the C9.25 since no-one makes a coma-free non-Edge SCT.  The spots for a C9.25/C9.25 Edge will differ from the spots for a C8, C11, C8 Edge or C11 Edge because the C9.25s' primary is significantly slower and the field - corrected or otherwise - is natively better.

 

As for size C11 vs. C9.25, having owned both (standard C11 and Edge C9.25) there's a big difference in mounting and handling.  Length is similar.  An extra 7# takes you from well within the capacity spec of many mid sized mounts to very upper limit of most mid-sized mounts.  Second, the C11 is MUCH fatter.  Harder to hold when positioning in the saddle, takes up more cargo space and storage space, etc.  I've used them both on a Takahashi EM-200.  The C9.25 is much, much easier to live with logistically than the C11.

 

Of course C8 to C9.25 the same argument applies in favor of the sveldt C8.  There's probably no more convenient 8" design for travel than the C8.  It rides easily on a light duty mount (CG-5/AVX) which neither of the others do, in the case of the standard C8, costs very little, and delivers aperture that's nothing to sneeze at.

 

Best,

 

Jim



#24 mark379

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Posted 20 June 2019 - 12:32 PM

An oldie but goodie. I once owned both at the same time.

If your talking visual. Yes the 9.25 is flatter than regular SCT's and shows great stars to the edge in up to 82 degree EP's . If you go to 100's then the edge shows them better. My pick would be the 9.25 for extra aperture and better on Planetary and DSO's.

Here's that old thread:

 

https://www.cloudyni...ide-comparison/

 

Ok, its well known around the forums that by design,  the 9.25 XLT has a little flatter field and less coma..BUT, how does it compare to the 800 Edge's flat field? Would you buy the 800 Edge over the 9.25 XLT or go for the extra aperture?



#25 jrbarnett

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Posted 20 June 2019 - 03:30 PM

An oldie but goodie. I once owned both at the same time.

If your talking visual. Yes the 9.25 is flatter than regular SCT's and shows great stars to the edge in up to 82 degree EP's . If you go to 100's then the edge shows them better. My pick would be the 9.25 for extra aperture and better on Planetary and DSO's.

Here's that old thread:

 

https://www.cloudyni...ide-comparison/

The white paper is actually really interesting.  The spots for the edge HD show obvious coma but little field curvature.  The spots for the Meade ACF show little or no coma but significant field curvature.  Neither design is perfect.  You get tight stars that squish into seagulls but remain tight off axis in the Edge and you get nice round stars edge to edge in the Meade but they get bloated the further off axis you go.  In the standard SCT you get a mix of both coma and curvature, as you'd expect.  But what about a standard SCT with a FF/FR in the optical train?  Notice Celestron didn't share that despite the fact that as an "astrograph" (their claim in the white paper) a standard SCT would almost certainly be so equipped.

 

I wonder whether a redesign of the Edge HD system that balanced curvature and coma correction a bit more in favor of tolerating a little bloat off-axis (curvature) and further reducing the coma wouldn't have been a better design.  Certainly for visual users it would be preferable I think.

 

- Jim 




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