Celestron_EdgeHD_SCT

A High Definition Telescope? Yeah… The Celestron EdgeHD!

Article Updated: 26 Apr , 2016

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In this new generation of everything high def – from computer screen to televisions – is it possible to create a high definition telescope? The answer is yes… And the designer is Celestron. As always, I keep my eyes and ears open when it comes to the latest in astronomy equipment. While I’ve seen a lot of things come and go over the years (including other Ritchey-Chretien and astrograph knock-offs), the Celestron EdgeHD is a design that I think really deserves a closer look…

schmidt-cassegrain_telescopeFirst let’s start the story off where it deserves to be started… the basic Schmidt Cassegrain design. Some four decades ago, the SCT was cutting edge technology. Its predecessor the Cassegrain, used a primary concave mirror and a secondary hyperbolic convex mirror to focus the light back through the hole in the primary to the eyepiece or camera. The Schmidt design allowed for a corrector plate to be added to the optical path to help eliminate spherical aberrations – the increased refraction or reflection of the light rays when they strike near the mirror’s edge. This produced great flat-field images and long focal lengths in an extremely compact design – but it also introduced a very expensive telescope. One the average consumer couldn’t afford.

Enter Celestron…

In 1970 Celestron telescope designers and engineers announced a revolutionary method of producing Schmidt-Cassegrain telescopes at a reasonable cost and in volume. This optical breakthrough was incorporated in the first Celestron C8. The popularity of the C8 Celestron telescope in the consumer marketplace led to the C5 Celestron telescope and then to larger versions, including an 11″ and 14″ telescope. The “orange tube” telescopes became an instant classic and many of them are still in use today… But the design could be a little bit better, couldn’t it? Yeah. It could be aplanatic.

Aplanatic telescopes can be designed with two aspheric mirrors, configured to correct spherical and coma aberrations – a design which minimizes astigmatism and can be optimized to have no vignetting across the field. What’s more, the aplantic design also allows for a significant reduction in scale sizes when it comes to astrophotography, making them extremely compatible with finely-pixilated modern imaging equipment, like CCD cameras. But that would also make it very expensive wouldn’t it? Yeah… It would. But still, that design could get a little bit better couldn’t it? Sure. It could be an astrograph!

In this case, the astrograph is a telescope designed for the sole purpose of astrophotography. Not so great if you want to use it visually… But just dandy if you’re interested in wide field surveys of the night sky. It’s a pure research grade telescope – designed to work in conjunction with a specific shaped photographic plate or CCD detector. With an astrograph you could work on things like astrometry, stellar classifications and, with time, even proper motion of nearby stars. An astrograph means the possibility of finding things like asteroids, meteors, comets, variable stars, nova, and even unknown planets. But an astrograph means you’re talking about a mighty expensive telescope, right? Right.

Enter Celestron…

optical-design

Just like 40 years ago when Celestron revolutionized the affordability factor of the Schmidt-Cassegrain design (once also the domain of researchers only), they are about to revolutionize amateur astronomy once again by giving the world its very first high definition telescope – the Celestron EdgeHD.

Is Celestron making promises it can’t keep? Let’s take a look at the track record of some major telescope manufacturers.

It hasn’t been that long since Meade also introduced a similar design telescope known as the ACF, or Advanced Coma Free. It was a knock-off of the Ritchey-Chretien design, and supposedly free of third-order coma and spherical aberration, and heavily advertised as being as the same design as the Hubble Space Telescope. Well, we all know what happened right off the bat with the Hubble, don’t we? Darn right. One little wrong tweak in the optical design led to a major Hubble error and one wrong move in poorly executed RCT design will lead to fifth-order coma, severe large-angle astigmatism, and comparatively severe field curvature.

When companies compete with comparative design models for the consumer, they’re putting out a lot of advertising hype your way. But let’s cut to the chase. Two companies… Both produced a sky navigation product – one failed and one endured. Which one? Yeah. The Celestron SkyScout. You’re getting the picture. Let’s take our own IYA Live Telescope as another example. The Meade ETX lasted through 28 observations and I have a Celestron 114 that’s 22 years old and I can’t even begin to fathom how many times it’s been used. Try calling or writing the companies for customer service or questions… See which one answers you and which one doesn’t.

20090429_osct11_coma_half-2

Will the Celestron EdgeHD telescope be all that? The image you see here was taken by Andre Paquette using Celestron EdgeHD Optics. I’ve examined it upside down, backwards, forwards and from edge to edge… and what I see are perfect stellar images. (Open the full-sized image and check it out yourself. You’ll be impressed!)

edgehdsellsheet_Page_2_Image_0005Celestron promises the light becomes more concentrated when focused precisely. This maximizes image brightness, improves resolution and limiting magnitude when compared to telescopes of equal aperture. I know for a fact that you can’t beat Celestron’s Starbright XLT coatings, because I’ve never had to recoat a Celestron mirror yet. I look at the modern ergonomic design and I don’t see “cool” the same way as others… I see a self contained unit that isn’t going to be dragging or snagging on things – one with cooling vents located on the rear cell allow hot air to be released from behind the primary mirror. I see a telescope that’s going to perform incredibly in both visual and photographic capabilities…

11093_cge_pro_1100HDSo where’s the bottom line? The cost. Don’t start selling your gold dental fillings or thinking about taking out a second mortgage on your home, because Celestron has done it again. Just like so many years ago when they made the SCT affordable to backyard astronomers, they are now putting cutting edge, research grade design telescopes into the realm of possible. The average price is only about 1/3 more for the optical tube assembly than a standard SCT and it gets even lower as the aperture goes up. If you need the complete telescope package with a mount and tripod? Sure. It’s expensive – but the high quality of the mount is what you’re paying for and it’s worth it. (Remember two little telescopes – one that lasted through 28 observations and one that’s still going strong after 22 years.) What kind of faith do I have in Celestron? The same faith I’ve always had. Every Celestron product I’ve purchased over the years is still functioning… and the same cannot be said of other “M”anufacturers.

Go on… Take a look at the Celestron EdgeHD for yourself! You’ll find much more information and illustrations at the Celestron EdgeHD Tour pages, and you can take a look at pricing, specifications, and other information through Celestron’s premier dealers such as OPT, telescopes.com, Scope City, High Point, Hands On Optics, Astronomics and Adorama.

What will they think of next??


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Dark Gnat
Member
Dark Gnat
July 16, 2009 1:27 PM

Slightly off topic:

I recently got the Celestron Binocular/Green Laser/Red flashlight kit, and I gotta say I’m impressed. I’m on a tight budget, so this was perfect. I can clearly see Jupiter’s 4 largest moons, Uranus, and lots of galaxies. I’m looking forward to veiwing Venus and the Moon, among other things.

The laser is cool, too. I love lasers, and this was an excellent deal. The red light will come in handy, as well.

I think I might be saving up for a Celestron scope, assuming I don’t get any more pay cuts. smile

Sili
Member
Sili
July 16, 2009 6:37 PM

You’re almost making me wish for nieces/nephews and godchildren.

Astrofiend
Member
Astrofiend
July 16, 2009 9:38 PM
Let me just preface this by saying it will come across harsher than intended – I enjoy your articles and the few exchanges that we’ve had in the comments section, BUT Jesus – that sounded pretty much like an AD to me, not a review. Big difference. Something to get of your chest in regards to Meade Tammy?! Any disclosures to make? I mean, come on – the whole article is a Meade put down and a Celestron ‘big up’. What’s with the consistently negative wording in regards to Meade? I.e: “It was a knock-off of the Ritchey-Chretien design” “supposedly free of third-order coma” “and heavily advertised as being as the same design as the Hubble Space Telescope.… Read more »
Fraser Cain
Admin
July 16, 2009 10:50 PM

Celestron doesn’t pay us to do reviews, if that’s what you’re wondering. Tammy gets gear and does reviews, but I pay her for the reviews, not the telescope manufacturers.

Tammy’s just naturally enthusiastic.

omnivorr
Member
omnivorr
July 17, 2009 12:27 AM

sorry,… but gush like that is anathema to intelligent interest in the product.
This “review” sounds like it was written by a ‘freshman’ in the Goebbel’s school of hypermedia studies.
…or did it come from “The Pond’s Institute” of anti-aging snake-oil?

…it’ll all end in botox/lobotomy, but gravity will win!

croysk
Member
croysk
July 17, 2009 6:07 AM
This “review” is so terrible it made me sign up to, well, basically to complain and agree with the “astrofriend”s post above. This post may seem harsh, but this is the first time I’ve ever felt the desire to do this. This article really is that bad. I am no great fan of Meade, nor of Celestron. I own two Celestron ‘scopes – a C8 and C11, among other manufacturers (a little Meade ETX90, Borg, Takahashi, etc). I accept the C8 and C11 for what they are – cheap compact scopes with relatively large aperture for the cost. I agree with pretty much everything “astrofriend” says above, though I perhaps wouldn’t go as far as to accuse Tammy… Read more »
Jon Hanford
Member
Jon Hanford
July 17, 2009 8:42 AM

Btw, the galaxy cluster presented in the article is none other than the Coma Cluster aka Abell 1656, for all galaxy-heads out there smile

William928
Member
William928
July 17, 2009 4:49 PM

WOW! i don’t know enough technically about scopes to comment on who’s right in this argument, but I do believe a few of you were a bit harsh with Tammy. This post is really directed at Tammy to get her opinion on which scope I should purchase as an amateur astromomy buff who has had a scope since high school (30 yrs. ago). I’ve looked at Orion Observer 70MM Altazimuth Refractor, Orion Transporter 70mm Refractor, and the Celestron Astromaster 76 Reflector. Would a reflector or refractor scope be best? i’m strictly interested in astromomy, so I believe a reflector may be the choice? I’d like to stay under $300. Any advice you can offer would be much appreciated.

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