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Equipment Discussions >> Cats & Casses

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David PavlichAdministrator
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Re: To those that said an Edge would blow me away... new [Re: freestar8n]
      #5621399 - 01/13/13 06:32 PM

Quote:

Quote:

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


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Peter in Reno
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Re: To those that said an Edge would blow me away... new [Re: David Pavlich]
      #5621496 - 01/13/13 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

Edited by Peter in Reno (01/13/13 07:44 PM)


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jrbarnett
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Reged: 02/28/06

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Re: To those that said an Edge would blow me away... new [Re: Taylor]
      #5621719 - 01/13/13 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


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bremms
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Reged: 08/31/12

Loc: SC
Re: To those that said an Edge would blow me away... new [Re: jrbarnett]
      #5621819 - 01/13/13 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.

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freestar8n
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Reged: 10/12/07

Re: To those that said an Edge would blow me away... new [Re: David Pavlich]
      #5622093 - 01/14/13 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.

Quote:

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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rmollise
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Reged: 07/06/07

Re: To those that said an Edge would blow me away... new [Re: Taylor]
      #5622212 - 01/14/13 07:41 AM

Quote:

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




No, there will be no difference.


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Alph
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Reged: 11/23/06

Loc: Melmac
Re: To those that said an Edge would blow me away... new [Re: rmollise]
      #5622795 - 01/14/13 02:34 PM

Quote:

Quote:

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




No, there will be no difference.



I think we had this conversation before. Optical alignment is critical for Hyperstar performance. The EdgeHD telescopes come out of factory aligned more carefully as stipulated by the design

Edited by Alph (01/15/13 01:06 PM)


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Eddgie
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Reged: 02/01/06

Re: To those that said an Edge would blow me away... new [Re: Alph]
      #5622935 - 01/14/13 03:54 PM

For Hyperstar use, Rod is right. This is done at the native focal lenght of the primary mirror and the Correcting elements in the baffle are not in the light train.

For Hyperstar imageing, it will be the same as the standard SCT.

Celestron even says the same thing in their white paper.


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fly2work
newbie


Reged: 10/21/12

Re: To those that said an Edge would blow me away... new [Re: AstroGabe]
      #5626832 - 01/16/13 07:27 PM

My Edge HD 1100 blows me away whether it is visual or imaging and mounted to the CGEM DX its rock solid! Mind you its been 14 years since I last owned a scope so quite a bit has changed!

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dscarpa
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Reged: 03/15/08

Loc: San Diego Ca.
Re: To those that said an Edge would blow me away... new [Re: amdizack]
      #5627973 - 01/17/13 12:09 PM

I've got one of the last made in the USA regular C-9.25s and it blows me away. Very sharp for lunar-planetary and DSOs. It's the equal of my IM-715D for lunar-planetary with very good seeing and smokes it when conditions are excellent. I use Naglers, a 13 Ethos and a 20 ES 100 in it a lot and don't find FC to be an issue. There's some coma but I don't notice it if I don't look for it. David

Edited by dscarpa (01/17/13 12:10 PM)


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GeneT
Ely Kid
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Reged: 11/07/08

Loc: South Texas
Re: To those that said an Edge would blow me away... new [Re: amdizack]
      #5628611 - 01/17/13 06:22 PM

If I ever buy another SCT, it will have EdgeHD optics.

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XwarpfactorX
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Reged: 11/29/12

Loc: California
Re: To those that said an Edge would blow me away... new [Re: GeneT]
      #5629007 - 01/17/13 10:23 PM

I've got a CPC 1100 HD on the way, can't wait to take that first look through it. I've never had a SCT before, only a fast newtonian. Coma is pretty bad.

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Patrick
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Reged: 05/16/03

Loc: Franklin, Ohio
Re: To those that said an Edge would blow me away... [Re: amdizack]
      #5629167 - 01/18/13 12:09 AM

I spent some time tonight with my new EdgeHD 8" and all I can say is this is the best scope I've ever owned.

When someone says that you can get the same image as a standard SCT at the center of the fov, they're right. BUT, with the EdgeHD, you no longer have to observe in the center of the fov...you're not constrained to making sure your object is centered.

When observing, I've always found myself fiddling with object positioning, trying to get it centered just right. It doesn't matter with the EdgeHD.

That really came home to me tonight while observing the Trap. The seeing wasn't too great, but the transparency was excellent. Nevertheless the stars were round without flaring all the way to the edge. I sat there looking at the Trap's splendor with it sitting 2/3rd of the way off center. That was amazing. I can't wait to see what this scope can do with great seeing.

Patrick


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Eddgie
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Re: To those that said an Edge would blow me away... new [Re: Patrick]
      #5629632 - 01/18/13 10:26 AM

Yes, looking through an EdgeHD is a much different experience than using a standard SCT.

I learned about field sharpness from using large achromats. While the field of a 6" f/8 achromat is not completly flat, it is indeed flatter than a C8, and the design is corrected for coma.

When I started using the 6" f/8 achrmoat, what I really discovered is that what makes refractors the great scopes they are is not what is at the center of the field. Heck most every bigger SCT I have owned was easily better at the center of the field than the 6" f/8 achromat.

But the first time I looked at the Double Cluster in the 6" f/8 achromat, the earth moved under me. The absoute brilliance of the stars even out to the edge of the field of a 22mm Panoptic was nothing short of awe-inspiring.

This was a view I had never had with any other telescope.

And this was the moment that I realized that differences in off axis performance in telescope design are far more important than the relatively small differences in how they pwerform at the center of the field.

And the EdgeHD 8" is an utterly superb off axis performer. The "Space walk" experience is far more apparent using a Nagler in an EdgeHD than it is using a Nagler in a standard SCT.

Wonderful scope. Ties with my 6" APO for producing the most aesthetically pleasing view.


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ewave
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Reged: 05/16/09

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Re: To those that said an Edge would blow me away... new [Re: Patrick]
      #5629732 - 01/18/13 11:14 AM

Quote:

I spent some time tonight with my new EdgeHD 8" and all I can say is this is the best scope I've ever owned.

When someone says that you can get the same image as a standard SCT at the center of the fov, they're right. BUT, with the EdgeHD, you no longer have to observe in the center of the fov...you're not constrained to making sure your object is centered.

When observing, I've always found myself fiddling with object positioning, trying to get it centered just right. It doesn't matter with the EdgeHD.

That really came home to me tonight while observing the Trap. The seeing wasn't too great, but the transparency was excellent. Nevertheless the stars were round without flaring all the way to the edge. I sat there looking at the Trap's splendor with it sitting 2/3rd of the way off center. That was amazing. I can't wait to see what this scope can do with great seeing.

Patrick



Great to see another great sample of the Edge. Can't wait to see how you like it when doing AP. The C9.25 Edge is the best SCT I've owned but I've only owned 3 SCTs in my life. Just wish the reducer for the C9.25 was out by now....more than a couple years waiting...


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Footbag
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Reged: 04/13/09

Loc: Scranton, PA
Re: To those that said an Edge would blow me away... new [Re: ewave]
      #5629821 - 01/18/13 11:59 AM

I'll relate my experience with the Edge. I first received the Edge 800 and did a bunch of visual observing while learning about my new mount. The views were amazing. I used it for about a month, and then one day noticed that the dovetail bar wasn't seated properly, I tried to fix it, but learned that the mounting holes were drilled off. I spoke to the vendor I purchased it from and they sent me a replacement.

I received the replacement and noticed my views were disappointing. I fretted about the scope I gave up. Then, the first time I used the 2nd edge for imaging, I noticed very odd star shapes in different directions. At first, I thought it was collimation, but after troubleshooting, I think it had to do something with the focuser/mirror lock mechanism. Like it was binding the mirror even when unlocked.

This time, my vendor referred me to Celestron. I have heard horror stories of Celestron's customer service, but I had a great experience. I explained my problem, and they hand selected a replacement. My first views through the new Edge, pop! Amazing views and detail. When imaging my star shape is perfect.

So, with the exception of the one OTA that had the problem, both of the 800's I've looked through were equally impressive.

Now, for those who say the performance is only better off axis, the performance is still better, right?

I really wonder if Celestron is taking their better mirrors and putting them into the Edge HD's. I seem to remember seeing a site which compared strehl's and the Edges seemed to perform very well compared to other SCT's. But, I can no longer find this site and am wondering if I made it up in my head.


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aa6ww
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Reged: 10/23/11

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Re: To those that said an Edge would blow me away... new [Re: Eddgie]
      #5630183 - 01/18/13 04:09 PM

Quote:

Quote:

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.




Try finding the Pup in your Edge scope, or try splitting IZAR on any given night. Try taking in the entire Andromeda in your Edge in one field of view. Every scope wants to have views a refractor can have, but only a refractor can do that. Ive never heard or a refractor that wanted to optics like any SCT. Seriously.
Every scope has its reason for existing, they are all as unique as people are. Once people realize this, the world will be a wonderful place!!

...Ralph


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Gord
Carpal Tunnel
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Reged: 01/06/04

Loc: Toronto, ON, Canada
Re: To those that said an Edge would blow me away... new [Re: aa6ww]
      #5630234 - 01/18/13 04:35 PM

Hmmm, I haven't tried the Pup yet (is it _ever_ going to clear up?!), but I have split Antares a few times now, but only with the C8. Never with the refractors. I've also never found a refractor that will show as much of Andromeda as the C14 has (definition of dark lanes, star clouds and globulars *in* M31).

The Edge HD has views with very similar characteristics as refractors. Well, very big refractors that is!

Clear skies,


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Lane
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Reged: 11/19/07

Loc: Frisco, Texas
Re: To those that said an Edge would blow me away... new [Re: Gord]
      #5630271 - 01/18/13 05:14 PM

I would like to own an HD, but here is my problem with that purchase:

The regular C11 is $1799 and a C11 HD is $3399 and the only true difference in these two scopes is a small lens mounted inside the telescope. So buying an HD is like spending $1600 for a corrector lens. Even Tak with their ridiculous accessory prices does not charge that much for a corrector.

Plus the simple fact that for only a few hundred more you can get a C14 instead of C11 HD.

Maybe it is worth $1600 to see a nice flat field with no distortion at the edges, probably is worth it, but I can't help feel they are taking advantage of us.


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Peter in Reno
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Loc: Reno, NV
Re: To those that said an Edge would blow me away... new [Re: Lane]
      #5630276 - 01/18/13 05:20 PM

I was getting annoyed with comatic stars around the center when imaging with regular C-8 at F/10 (without F/6.3 focal reducer-corrector). So I replaced it with EdgeHD and to me it was worth the extra expense of getting flat FOV from edge to edge. Celestron did it right with EdgeHD scopes.

Peter


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