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To those that said an Edge would blow me away...

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#1 amdizack

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Posted 12 January 2013 - 03:23 PM

You were RIGHT! Unreal compared to my Nexstar 8SE. I'm seeing things I've never been able to see before!

I'm (even more) addicted now! :bow:

#2 Footbag

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Posted 12 January 2013 - 04:41 PM

I had a serious "Wow!" moment when first looking though my Edge after coming from a CPC-800. I think Celestron really did a nice job on them.

#3 Motokid600

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Posted 12 January 2013 - 06:10 PM

I have a Cpc1100... your making the envy boil now lol. Let's just say I got an 11" edge HD.. visually.. would I see a difference?

#4 ewave

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Posted 12 January 2013 - 06:21 PM

I have a Cpc1100... your making the envy boil now lol. Let's just say I got an 11" edge HD.. visually.. would I see a difference?

Perhaps you just might. I went from a CPC-11 to a C9.25 Edge and my view of the planets improved. I also liked the pinpoint stars across the entire field of view, even if it is only about one degree.

#5 David Pavlich

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Posted 12 January 2013 - 06:36 PM

On axis, I would think that if both scopes are XLT coated and the optics are, other than the flattener, the same, there would be so little difference that you wouldn't be able to tell. The only way to truly test them is side by side using the same ep and having a couple of people looking through them.

Having said that, I've read a couple of new owners that are SC veterans say that the optics of their Edges were better than their other SCs. It's tough to tell. I owned two C14s and it was clear that the first one I owned was better and that was without side by side comparison, it was that stark.

David

#6 Scott in NC

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Posted 12 January 2013 - 07:40 PM

Having said that, I've read a couple of new owners that are SC veterans say that the optics of their Edges were better than their other SCs. It's tough to tell. I owned two C14s and it was clear that the first one I owned was better and that was without side by side comparison, it was that stark.


Yeah, I'm wondering if the "improvement" that a lot of people think that they see really has to do with Edge vs. non-Edge optics or just simply the normal inter-unit variation in optical quality that seems to be commonplace with mass-produced SCTs. :shrug: Either way, what's important here is that the OP seems to have ended up with a good one! :)

#7 coopman

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Posted 12 January 2013 - 07:50 PM

I have yet to see any Edge HD users say that they were disappointed with their scope. I have noticed that a fair no. of them have been sold in the last 3 or 4 months on Astromart. I am not sure why, though.

#8 Footbag

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Posted 12 January 2013 - 09:41 PM

I have noticed that a fair no. of them have been sold in the last 3 or 4 months on Astromart. I am not sure why, though.


Maybe they're going bigger? ;)

#9 amdizack

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Posted 13 January 2013 - 02:17 AM

I have a Cpc1100... your making the envy boil now lol. Let's just say I got an 11" edge HD.. visually.. would I see a difference?


Easy--YES! I went from a C8 to the Edge 8 and noticed a big difference just for visual. Planets, nebula, star clusters--very crisp and clear through my edge!

#10 freestar8n

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Posted 13 January 2013 - 04:31 AM

On axis, I would think that if both scopes are XLT coated and the optics are, other than the flattener, the same, there would be so little difference that you wouldn't be able to tell.



This assumes all telescopes behave according to their theoretical spot diagrams - but if that were the case then all designs corrected for spherical and chromatic aberration would be perfect and equivalent on axis - but that is obviously not true.

You need to consider the tolerances in the design, ease of collimation, and sensitivity to decollimation - among other things. A Maksutov is theoretically excellent on axis, but the surfaces need to be made exactly right or the result will be terrible - hence their higher cost.

The Edge design, assembly, and sensitivity to collimation error is very different from a normal SCT - while still being based on spheres. So I was not surprised when users noticed an improvement in on-axis performance - which does seem to be the trend in reports. Theoretical performance based on a spot diagram is very different from the realized performance and range of quality in the delivered product.

Frank

#11 04yellowf150

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Posted 13 January 2013 - 07:01 AM

I just recieved my 8inch edge as well. Cant wait to mess with it. Its my 1st scope :)

#12 telfish

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Posted 13 January 2013 - 08:52 AM

Does that mean the edge is more tolerant of poor collimation and holds a good collimation better?

#13 freestar8n

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Posted 13 January 2013 - 09:13 AM

Any design with reduced coma will be less sensitive to small collimation errors. And if the collimation changes a bit over time - that would also be less noticeable.

Frank

#14 David Pavlich

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Posted 13 January 2013 - 10:33 AM

On axis, I would think that if both scopes are XLT coated and the optics are, other than the flattener, the same, there would be so little difference that you wouldn't be able to tell.


This assumes all telescopes behave according to their theoretical spot diagrams - but if that were the case then all designs corrected for spherical and chromatic aberration would be perfect and equivalent on axis - but that is obviously not true.

You need to consider the tolerances in the design, ease of collimation, and sensitivity to decollimation - among other things. A Maksutov is theoretically excellent on axis, but the surfaces need to be made exactly right or the result will be terrible - hence their higher cost.

The Edge design, assembly, and sensitivity to collimation error is very different from a normal SCT - while still being based on spheres. So I was not surprised when users noticed an improvement in on-axis performance - which does seem to be the trend in reports. Theoretical performance based on a spot diagram is very different from the realized performance and range of quality in the delivered product.

Frank


Like I said, all things being equal which means the optics are essentially the same quality. Under typical conditions (not in an optical lab) and "all things being equal", it would be difficult to see a difference on axis.

David

#15 Eddgie

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Posted 13 January 2013 - 10:49 AM

I have a Cpc1100... your making the envy boil now lol. Let's just say I got an 11" edge HD.. visually.. would I see a difference?



Assuming optical quality is similar, at the center of the field, the view would not be better.

My last C8 had excellent optics, and on planets and the moon, at the center of the field, the view was about exactly the same.

All of the benefit of the EdgeHD design is to be found in the off axis performance.

The value proposition for the EdgeHD (in my own opinion) is for imagers and for people that enjoy using modern ultra-wide field eyepeices.

If you are content with Panoptic class eyepeices, it is very difficult for me to say that the EdgeHD will be a better scope. With Panoptics or similar high quality 68 degree wide field eyepieces, the abberations coming from the telescope are not magnified enough to be prominent.

If you go to a Nagler (or similar 82 degree AFOV eyepeice) or Ethos (or similar), for the same size true field of view, the magnificaiton of the eyepeice will make the abberated blur at the edge of the field easier to resolve, so the outside of the field will not appear as sharp.

The EdgeHD makes the scope visually sharp all the way across when using these new modern wide fields.

For someone that is content with Panoptic type eyepeices (or other similar narrower field types with excellent off axis performance), the EdgeHD may not be as compelling.

And for those that say that they only look at the center of the field, there would appear to be no value whatsoever in the EdgeHD scope design.

But once you become accustomed to using a telescope that presents a pinpoint image right to the field stop of modern wide field eyepieces, you very quickly become sold on the value proposition of the EdgeHD design.

Lots of people say "refractor like," and this has been my own message for a decade. The real value of refractors is their coma-free performance.

The EdgeHD is not "refractor-like." It is "refractor equal" in terms of across the field performance.

It is the only reflecting telescope I use that stands toe to toe with my 6" APO and provides an equal across the field viewing experience. With the 31mm Nagler, the view is amazingly brilliant.

Of course I am limited to the 1.1 degree true field in the EdgeHD 8", but since getting the EdgeHD 8" the 6" APO has been a hanger queen more than ever before. It only comes out for the Milky Way when I want 2 degree fields. If it will fit in the field of the EdgeHD 8", the view is better in the EdgeHD 8".

The best SCT ever made in my opinion.

Is it right for everyone? Dedicated planatery observers will find no benefit and narrow feild eyepeice users will see only a tiny improvement.

But imagers and Nagler, and Etho fans will be in a new place.

A footnote.. When using Ethos and even Naglers, seeing will keep stars from appearin pinpoint in larger SCTs even at the center of the field. The field will still appear much sharper in the EdgeHD scopes because it is all in focus (much of the "Bloat" we observe in SCTs is simply due to the field only being partially in focus), but stars may still appear bloated at the center when you compare the view of a 21mm Ethos to a 35mm Panoptic.

And the bigger the SCT, the worse this will occur.

Even at the center of the field, I prefer the 41mm Pan to my 31mm Nagler in the C14. Stars are just more pinpoint at the center.

For this reason, the bigger the SCT, the more serious the problem becomes, and the value propsition shifts if the user tends to have migrated to Panoptics vs Naglers.

For visual use, I am not sure that the C14 EdgeHD value proposition is still there. I have struggled with this myself. I am not sure I would use Naglers in the C14, so the extra benefit of sharper off axis performance might not be important. I am a staunch advocate of Panoptic class eyepeices in the C14 because of the seeing bloat issue, and the improved off axis performance is negated if you are only using Panoptics.

#16 Taylor

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Posted 13 January 2013 - 10:57 AM

Would having an Edge HD make a difference for Hyperstar imaging at all?
Or would it be equivalent in results to a regular C11?

#17 David Pavlich

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Posted 13 January 2013 - 12:00 PM

Would having an Edge HD make a difference for Hyperstar imaging at all?
Or would it be equivalent in results to a regular C11?


Again, assuming that the Edge 14" and the standard Celestron 14" mirrors were equal and Hyperstar imaging is the main reason for the scope, then no, I wouldn't pay the extra for the Edge. The corrector lenses are in the baffle tube. The Hperstar uses only the corrector plate and the primary mirror. The primary mirror is around f2, hence the reason that the HS is f2. In the 14, I believe it's f1.9.

The corrector lenses would essentially become useless weight for HS imaging alone.

David

#18 freestar8n

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Posted 13 January 2013 - 12:12 PM

Like I said, all things being equal which means the optics are essentially the same quality. Under typical conditions (not in an optical lab) and "all things being equal", it would be difficult to see a difference on axis.


Well - if all things are equal - then all telescopes are equal, and there is no possible discrepancy at all as long as the spot diagrams are good. Instead there are a wide variety of designs possible, and the ones that become popular at low cost are the ones that have generous design tolerances and can be made well and reliably.

In other words, all things being equal in the making of individual components may end up with a very different spread of results in the output - due to the difference in tolerances of the design. So - all things being equal, any difference in the design could make the performance quite unequal - and the tight tolerances on a maksutov I mentioned are an example.

There may be other differences in the manufacturing that result in overall improved performance - I don't know. But the main thing is - we know the designs are different, so that is an inequality right there. And there may be other differences also.

Frank

#19 Taylor

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Posted 13 January 2013 - 12:31 PM

Would having an Edge HD make a difference for Hyperstar imaging at all?
Or would it be equivalent in results to a regular C11?


Again, assuming that the Edge 14" and the standard Celestron 14" mirrors were equal and Hyperstar imaging is the main reason for the scope, then no, I wouldn't pay the extra for the Edge. The corrector lenses are in the baffle tube. The Hperstar uses only the corrector plate and the primary mirror. The primary mirror is around f2, hence the reason that the HS is f2. In the 14, I believe it's f1.9.

The corrector lenses would essentially become useless weight for HS imaging alone.

David


Thanks for the info David, I didn't know that.

#20 AstroGabe

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Posted 13 January 2013 - 04:34 PM

I completely agree. I received my new (to me) 9.25 edge a few weeks ago. First light was incredible. My 21 ethos just barely fit the double cluster in the FOV, but the view was very sharp. I had previously owned a C9.25 a few years ago, and quickly sold it since I had issues with pinpoint stars. This one is definitely a keeper!

Gabe

#21 David Pavlich

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Posted 13 January 2013 - 06:32 PM

Like I said, all things being equal which means the optics are essentially the same quality. Under typical conditions (not in an optical lab) and "all things being equal", it would be difficult to see a difference on axis.


Well - if all things are equal - then all telescopes are equal, and there is no possible discrepancy at all as long as the spot diagrams are good. Instead there are a wide variety of designs possible, and the ones that become popular at low cost are the ones that have generous design tolerances and can be made well and reliably.

In other words, all things being equal in the making of individual components may end up with a very different spread of results in the output - due to the difference in tolerances of the design. So - all things being equal, any difference in the design could make the performance quite unequal - and the tight tolerances on a maksutov I mentioned are an example.

There may be other differences in the manufacturing that result in overall improved performance - I don't know. But the main thing is - we know the designs are different, so that is an inequality right there. And there may be other differences also.

Frank


I'm not quite sure what you're getting at, but I thought the discussion was Edge performance relative to a standard Celestron SC. I wasn't aware that other types were involved. I qualified my remarks by stating on axis performance of telescopes with equal quality optics. I still contend that there would be negligible difference between an Edge and a std. Celestron SC, especially under typical viewing conditions.

I'm not an optical engineer and could care less about spot diagrams or Roddier tests or tests by the Sears optometrist. Under real world conditions where 99% of SC users are doctors, lawyers and indian chiefs, not optical engineers, again, it would take a very keen eye to see the difference.

In the end, if you want that extra sharp performance of the outer part of the view, then by all means, purchase the Edge. Or, if you're an imager, purchase the Edge. But if you want to have nice views and aren't overly concerned that the stars aren't pinpoint from pillar to post, you can save some money and get a standard SC and maybe use that saved money to buy an extra ep or filter.

David

#22 Peter in Reno

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Posted 13 January 2013 - 07:34 PM

I used to own a regular C-8 and currently own a C-8 EdgeHD. I was not expecting performance increase for visual use but I did notice an improvement. I have tried to visually view M51 with regular C-8 SCT using 31mm Nagler and 13mm/8mm Ethos eyepieces and could not easily see M51. With EdgeHD, I was quite shocked not only to see both nucleus of M51 but the arms connecting between both nucleus as well. Viewing M51 with 8mm Ethos eyepiece was even better than lower power eyepieces with EdgeHD.

I don't know whether Celestron improved quality of EdgeHD scopes but the only part I noticed is an improvement is the way Celestron centers the lens corrector. They now use 4 set screws at the front cell use to precisely align the lens corrector. In regular SCT scope, they use either corks or paper shims to align the lens corrector which are a total joke.

The reason for precision centering of lens correctors is for Hyperstar so that collimating with Hyperstar is easier. So with precision centering of lens corrector could give better views visually through the eyepiece.

Celestron's 4 set screws

Peter

#23 jrbarnett

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Posted 13 January 2013 - 09:23 PM

But refractors - particularly faster ones - have a fair amount of field curvature. Shouldn't the EdgeHD be better in the FC department?

- Jim

#24 bremms

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Posted 13 January 2013 - 10:20 PM

I've had and used a fair number of Celestron SCT's. Not a huge number but around 10. I dont like the off axis coma in a standard SCT . For an F10 system they are not very good off axis, plus they have a good bit of field curvature. Side by side.. my 6" newt gave better planetary images than any of the C8s I've had. None of mine had great optics. A couple were OK and one or two were not so good. They are portable, give decent on axis images, but give poor off axis images, very sensitive to collimation, good bit of scattered light and image shift. I might consider an edge in the next year. as it seems to be so much better off axis. My C11 is good but not portable, but I still have to deal with the off axis images and field curvature.

#25 freestar8n

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Posted 14 January 2013 - 04:31 AM

I'm just referring to the two designs here: comatic sct and flat field aplanat with corrective lenses. If the components of two such telescopes are made and assembled with equal care and effort, the end result may be very different since the designs are different and the impact of small errors in tolerance are different. It could be worse for Edge or better - but there is no reason to think they would be the same.

it would take a very keen eye to see the difference.



I don't know how you could quantify the difference without knowing the actual performance in the field. The reports from users are fairly consistently positive that they do notice an improvement on axis. There is no reason to think that is a mistake or an illusion - it just means that, indeed, all things are not equal when it comes to comparing actual telescopes even though their theoretical performance should be similar.

Frank






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