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Celestron C80ED-RGT Refractor

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19 years 1 month ago #12472 by gnason
Replied by gnason on topic Re: Celestron C80ED-RGT Refractor
Here's my comparison of the Celestron 80ED and Orion 80ED scopes. Feel free to ask any questions.


"With clear nights few and far between lately, I eventually got a chance to match my Orion 80ED against Celestron's 80ED (on loan) on the 24th March and 2nd April. Seeing was excellent on both nights but the Moon interfered with viewing deep sky objects on the 24th and the night of the 2nd April was somewhat hazy.

Both telescopes are random off-the-shelf models. I've owned my Orion 80ED for about 9 months and obtained the Celestron 80ED from the local Celestron dealer.


Build Quality and Components

The telescopes are both 80mm f/7.5 models. Rumours have it that the optics are from the same factory but there is no definite confirmation of this to my knowledge. Whatever about the optics, the optical tube assemblies certainly bear no relation to each other in appearance.

The Celestron 80ED is built like a tank and extremely robust. As I mentioned previously, it's almost Russian in that respect but is in fact built in China. Everything is black bar the focuser wheels. There are no plastic parts other than the end caps. The tube ring is a heavy metal assembly held on to the OTA by a twin clasp mechanism. It works well and holds the OTA very securely. The integral dovetail is designed to fit Advanced GT CG5 mounts and a variety of other similar Celestron/Vixen mounts. It also has ¼-20 threads for tripod mounting.

The Celestron 80ED is more curvy than a typical astronomical refractor but Celestron initially began marketing it as a spotting scope so perhaps this is not unsurprising. The company is now releasing two astronomical versions, the 80ED-R and 80ED-RGT on the CG-5 and CG-5 GT mounts. The telescope measures 575mm in length with dew shield attached, no diagonal fitted and with focuser fully racked in. The tube circumference is 28.5mm. Movement of the 2" rack and pinion focuser assembly is a bit stiff for my liking rendering it difficult to achieve fine focus. Adjusting the four screws underneath makes no difference. If this were my scope, I would strip the heavy sticky grease off and use lighter grease instead. It should work well then. The locking screw works perfectly. Shining a light into the lens reveals three uniform medium green reflections with no unevenness so no complaints with the multi-coatings. There are two baffles in the tube and one in the focuser drawtube. The dew cap again is a heavy metal affair, which screws on to the tube assembly. Unfortunately, the plastic lens cap is a poor fit and falls off when the scope is turned on end. However, this is a trivial matter, easily rectified by a couple of strips of tape or felt.

The Celestron 80ED comes complete with a 6 x 30 finderscope (dovetail mount), 45º erect image 1.25" diagonal and 25mm Plossl (24x) so all the user has to do is supply a tripod. The astronomical versions come with a 6 x 30 finderscope, erect image 1.25" diagonal and 25mm Plossl (24x). Thanks to a flared slot, it's easy to slide the finderscope dovetail in at night.

The Orion 80ED, made by Synta in China, looks larger due to the oversized tube. It measures 650mm in length with dew shield attached, no diagonal fitted and with focuser racked in. The tube circumference is 32mm. As everyone knows, the Orion 80ED is a rather boring gunmetal grey. One wonders why Orion didn't have the OTA painted white or even black? Although lacking the Celestron's tank-like build, the Orion 80ED is more than robust enough to stand up to astronomical use. It's made by Synta in China. Although the Orion's Crayford focuser has its detractors with some owners fitting alternative focusers such as the Moonlite CF2 or FeatherTouch, I find it a pleasure to use visually, being smooth, precise and easy to achieve fine focus with. Were I an astrophotographer however, I would have to modify the focuser assembly (details available on the Orion 80ED site) as the lock screw has insufficient bite (a common problem with this telescope) or replace the focuser entirely.

The Orion 80ED comes as an OTA only; tube rings, finderscope (dovetail type), diagonal and eyepiece must be purchased separately. Alternatively, it can be purchased as a package; the SkyView Pro 80ED EQ. It's a mystery to me why telescope manufactures can't make dew caps to fit properly The Celestron cap is so loose it falls off while Orion's is so tight it's difficult to remove without pulling the dew cap away at the same time. I attach the Orion tube rings to a Celestron dovetail fitted with ¼-20 thread for tripod use. Shining a light into the optics revealed two uniform medium green and one pale purple coating (not white as I incorrectly indicated in a previous posting), so a less than adequate coating on one surface. Like the Celestron 80ED, there are two baffles in the tube and one in the drawtube.

Collimation/Star Test

I allowed both telescopes to cool down for at least one hour. Eyepieces and equipment used: Televue 8mm Radian with Televue 2.5x Powermate (187x), Celestron 1.25" 90º diagonal, Manfrotto Triman tripod with Manfrotto 029 head.

The Celestron 80ED was in perfect collimation, just as well as there doesn't seem to be any way to adjust this other than as a factory job. Intra-focal and extra-focal rings were concentric and almost identical, just a fraction of overcorrection. The Orion 80ED was also in perfect collimation. Although the lens has no adjustment screws, it is possible to adjust the collimation slightly on this scope using the focuser assembly and shims if needs be. Again, intra-focal and extra-focal rings were concentric and almost identical, just a fraction of undercorrection. Edge correction was excellent in both telescopes; the in-focus star image with single diffraction ring was visible right to the edge of the FOV with virtually no distortion. Inside focus, both telescopes displayed a slight magenta fringe and outside focus, a slight green fringe. No colour is apparent in focus. So, overall, very well colour-corrected for ED doublets.

Observing

Despite a bright Moon, thankfully hidden behind the house, both telescopes gave me incredible wide field views of the Orion Nebula complex from NGC1981 down to Iota Orionis and Struve 747 using the 13mm T6 (46x). The four stars in the Trapezium were easily visible and pinpoint. Open cluster M35 in Gemini was a sparkling array of pinpoint stars as were the Auriga Messier clusters. Both scopes split Castor at 75x. It really was impossible to detect any difference optically with deep sky objects and a few double stars. The scopes performed brilliantly.

Turning to Saturn, both scopes took 150x and 187x easily on both nights so I increased power to 200x (Vixen 7.5mm Plossl/2.5x Powermate) and the views still didn't breakdown. Unfortunately, I didn't have any eyepieces to hand allowing me to go higher to test the upper limits but I suspect 230x/240x was possible. The planet looked superb, almost in 3D, a gorgeous pale yellowish-ochre orb floating within the rings. The shadow of the planet on the rings was clearly visible as was the Cassini Division and banding on the planet's surface. No false colour was apparent. After swapping scopes a few times, I must say I preferred the view through the Celestron 80ED. Detail was just that bit sharper and more defined. The diminutive but superb Vixen 7.5mm Plossl incidentally outperformed the 8mm Radian (like David & Goliath when stacked side by side!). No amount of money would persuade me to part with this eyepiece (not a current model - can't find it anywhere on the Net but similar to this 7.3mm version in appearance: shop.centre.net.au/index.html?cat=0007JJ...00NRC&it=product

Jupiter took 187x and 200x with no problems whatsoever. The SEB, NEB, EZ and dark polar regions were readily visible. Fainter but still seen were the STB, NTB, STrZ and NTrZ. No false colour was apparent. Once again, the Celestron 80ED provided a slightly superior view than the Orion 80ED. As with Saturn, the views at 200x using the Vixen 7.5mm Plossl/2.5x Powermate were superior in terms of sharpness and contrast to that at 187x with the 8mm Radian/2.5x Powermate. Unfortunately, The GRS was not favourably placed on those two nights to compare views.

I had tested both scopes on the Moon on a previous night and found it difficult to tell the difference. Both showed a similar tiny amount of yellow/green colouration on one side of the rim and both provided excellent sharpness and contrast on lunar features. After some telescope swapping, I decided the Celestron 80ED enjoyed a slight edge in terms of sharpness and detail.

Conclusion

Because of the Crayford focuser, I found the Orion 80ED nicer to use than the Celestron 80ED but with re-greasing, the rack and pinion focuser should work well. I could not detect any difference between the two telescopes during deep sky viewing but for planetary viewing, the Celestron 80ED definitely shaded it. Quite a remarkable achievement for a spotting scope! Considering my Orion 80ED is not the only one sold with less than perfect coatings and I have yet to hear of any problems with the Celestron 80ED, it would appear Celestron's quality control is currently better. I've read a few comments now suggesting that Synta/Orion handpicked the early models and later scopes are exposed to the vagaries of less perfect quality control. Let's hope that Celestron does not let its quality control slip in the same way. Overall, both telescopes are very good ED refractors and it is great to have this level of quality at such low prices. However, if I had to choose between the two telescopes I tested, I would opt for the Celestron 80ED because of its slightly superior optics. Like Orion, Celestron has a winner on its hands and the OTA only (spotting scope version) and new astronomical versions should sell well."


Gordon

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19 years 1 month ago #12474 by gnason
Replied by gnason on topic Re:

Gordon, It was your review that caught my eye in the first place, I have to say congratulations on a thorough review of this scope :D I'm still very keen, and it will be interesting to see if A&S will introduce the 'pricematch' offer. The 100ED looks great also, must check the budget though


Thanks Keith. Believe me, it was a fair review. Don't be in any doubt - A & S will match prices!

As regards the SLT series, are these achromats?


Yes. My advice is to go for one of the ED models. I'm thinking of the 100ED myself as soon as the astro models on the GT mounts cross the Atlantic (if I can talk myself out of buying a Tak 102 NSV!)

By the way, Have any of you had any problems bringing a scope on board an aircraft as part of your 'hand luggage'? I'm bringing the etx70 with me next week on hols, so it should wrap up nicely in that bag supplied with it.


My wife would kill me if I brought a scope on holidays abroad so I just slip in my 15x50 IS binos!

Gordon

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19 years 1 month ago #12483 by dmcdona
Replied by dmcdona on topic Re: Celestron C80ED-RGT Refractor
Keith G - I took the ETX70 to the States. The only issue arose when it went through any (and all) of the scanners - I was stopped each time and aske to open the bag. When they had a good look and saw that it was a telescope as opposed to some kind of weapon/missile, they were happy enough. One word of warning, explain that its delicate and you don't want mucky fingerprints all over the objective :D

By the way - the supplied ruck sack is great - just pad it up with some (clean) socks/undies. It'll go under the seat in front no problem.

Cheers

Dave McD

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19 years 1 month ago #12489 by albertw
Replied by albertw on topic Re: Celestron C80ED-RGT Refractor
Hi,

I pestered the Airport Police before bringing my scope (4" Mak) to Italy for the Venus transit; their advice for carrying scopes on planes was the following:

1. Wrap it well in your hand luggage but ensure that you can get at it quickly, since you probably will be asked to open it.

2. Have the manual in the bag. This is really just to show that it is a telescope, as a non astronomer security guard may not be familiar with different types of scopes and may simply not believe it is a telescope.

3. Have an eyepiece with you. Again just in case there is a very suspicious security guard, you can demonstrate that it is a telescope.

4. If you are bringing it somewhere for a specific reason (eg for a transit/eclipse) bring some documentation about that. A copy of S&T that has an article on it.

5. Wrap the mount very very well as it will have to go in the hold, probably as oversize baggage. You will not be allowed to take it as hand luggage (the little ETX mount is probably an exception!).

Its all about trying to make this as hassle free an operation as possible.

That said, in Dublin airport I didnt even have to open the bag. They asked what it was alright and were happy enough with my answer, I expect this has changed with their tougher security checks. The Italians wanted me to open the bag so they could look at the microscope (ah language barriers!).

You shouldnt have any problems bringing a small scope with you.

hth,
~Al

Albert White MSc FRAS
Chairperson, International Dark Sky Association - Irish Section
www.darksky.ie/

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