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Celestron C8 XLT Orange tube first light.

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#1 Julio

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Posted 07 February 2013 - 11:36 PM

Well I decided that a faulty USA made Starbright 9.25 I received had to go and purchased a new orange tube C8. To be honest I was not expecting much from a C8 due to the decreased aperture and increased field curvature. The C8 in question is a Nextstar C8 XLT fastar model sold by Highpoint. A visual inspection of the scope revealed good-to very good mechanics, exception being the corrector retaining ring being warped and slightly bent where the screws attach to the front cell. The package includes the very skimpy and barely functional accessories; luckily I had a 99% dielectric diagonal and some good quality EPs. Seeing conditions were far from ideal for a first light but did improve as the night progressed, I would say 2/5 seeing checking the CSC for my area. With the scope cooled and collimated I took a glance at Polaris to perform a star test. Man was I chocked! The star pattern looked almost identical with equal in and out of focus range. The CO shadow was identical in size with 4.5mm defocus in and out of focus. The defocused rings at 300X, defocused to 3-4 showed equal brightness and texture on both sides of focus, sometimes It was difficult determining which side of focus I was in, they were so similar. There was no noticeable image shift as focus was reached! The star test pattern looked better than my Intes scope. Aimed the C8 towards Jupiter and the view was spectacular, I could easily see detail within and around the GRS, the South temperate belt showing plenty of swirls and detail, the southern equatorial belt showed the vast turbulence seen in pictures especially around the GRS and a multitude of colors ,ovals, festoons and cloud markings. This was all seen in 2/5 seeing with wispy light clouds blocking my view here in South FL. Focus was easily achieved quickly without ambiguity. Trapezium showed all 6 stars clearly and with good nebulosity. I lack the critical experience to numerically judge the optics on this C8, but with a better visual experience than the Intes 1/8 wave .97 strehl and the ED100. I would say this C8 is “diffraction limited” excluding CO. Looks like my optically excellent ED100 will be up for sale soon, it appears Celestron is getting their “stuff” together or I got lucky. :jump:

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#2 magnus

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Posted 08 February 2013 - 03:24 AM

Congratulations to your new scope! Nice report; seems like you`ve got a winner. Testing a new scope with the results you describe are what I would say the answer to the question: what is happiness?
And 8" SCT is an outstanding scope: small and yet aperture for serious observations. And no monster mount is required to hold it steady.

Magnus 57N.
C8 Orange Pacific -73

#3 aa6ww

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Posted 08 February 2013 - 03:33 AM

Well I decided that a faulty USA made Starbright 9.25 I received had to go and purchased a new orange tube C8. To be honest I was not expecting much from a C8 due to the decreased aperture and increased field curvature. The C8 in question is a Nextstar C8 XLT fastar model sold by Highpoint. A visual inspection of the scope revealed good-to very good mechanics, exception being the corrector retaining ring being warped and slightly bent where the screws attach to the front cell. The package includes the very skimpy and barely functional accessories; luckily I had a 99% dielectric diagonal and some good quality EPs. Seeing conditions were far from ideal for a first light but did improve as the night progressed, I would say 2/5 seeing checking the CSC for my area. With the scope cooled and collimated I took a glance at Polaris to perform a star test. Man was I chocked! The star pattern looked almost identical with equal in and out of focus range. The CO shadow was identical in size with 4.5mm defocus in and out of focus. The defocused rings at 300X, defocused to 3-4 showed equal brightness and texture on both sides of focus, sometimes It was difficult determining which side of focus I was in, they were so similar. There was no noticeable image shift as focus was reached! The star test pattern looked better than my Intes scope. Aimed the C8 towards Jupiter and the view was spectacular, I could easily see detail within and around the GRS, the South temperate belt showing plenty of swirls and detail, the southern equatorial belt showed the vast turbulence seen in pictures especially around the GRS and a multitude of colors ,ovals, festoons and cloud markings. This was all seen in 2/5 seeing with wispy light clouds blocking my view here in South FL. Focus was easily achieved quickly without ambiguity. Trapezium showed all 6 stars clearly and with good nebulosity. I lack the critical experience to numerically judge the optics on this C8, but with a better visual experience than the Intes 1/8 wave .97 strehl and the ED100. I would say this C8 is “diffraction limited” excluding CO. Looks like my optically excellent ED100 will be up for sale soon, it appears Celestron is getting their “stuff” together or I got lucky. :jump:

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Its a new moon weekend, I hope you can get out and use that good looking scope on some real deep space objects. I'm a big fan of the orange tube Celestrons!

...Ralph

#4 stevew

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Posted 10 February 2013 - 02:19 AM

It's absolutely wonderful that we keep hearing more and more reports like this about Celestron SCT's.

I have always thought of my C8 as a staple of my telescope collection.
It can just do so many things so very well.

Congratulations, and thanks for the great report.

Steve

#5 azure1961p

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Posted 10 February 2013 - 09:46 AM

I think you are right on both counts: Celestron got its QC. under control and you got lucky. Those XLT coatings with what looks like a levitating secondary are something huh ? Glad to hear your success story.

Pete

#6 gfeulner

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Posted 10 February 2013 - 11:09 AM

Love your post. In 1975 I bought a C8 from Roger Tuthill. It had no coatings but I still remember the textbook star patterns it had. About 10 years later I got Astro-Physics fever and bought the 6" F8 ($1440.00!!). I love that scope and still have it. Eventually I sold the C8 but over the years I thought about the C8's performance and portability. I decided last month to look for a good used C8 maybe a '70's orange tube or later model. I picked up a "classic" C8 made around 1989. I was a little skeptical at first but figured what the heck I'll give it a shot. When I got it I was "lucky" enough to have a bad case of bronchitis and ear infection so I had to wait to see what it could do. A few days ago I set it up and gave it a slight collimation. The seeing was decent but nothing special. I first did the in and out of focus test and like you, I couldn't tell the difference. Very encouraging. I put it on Jupiter and was astounded at the image. At 260x it was as sharp as a tack! The moons looked just like they do in my 6". Perfect round discs. Next was the trapezium. E & F were absolutely no sweat. I always see E in the 6" and C11 but not always F. I did a double take and was talking to myself! Went to the doubles 42 and 52. Perfect textbook splits. One of the hardest doubles for me is Eta Geminorum. My C11 shows it if the seeing is very good and the 6" usually does. Even at about 100x on the C8 I saw the companion right away. At 260x it was beautuful. Needless to say I'm very impressed with this particular C8. I guess once in awhile a bad one will slip through but it seems that the C8's on average are very good indeed and a real bagain if you get a good one. Gerry

#7 Eddgie

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Posted 10 February 2013 - 11:26 AM

I believe that the C8s have over the decades been the best made (optical quality) of the Celstron SCTs. The variation in the quality of the larger SCTs I have owned, tested, or seen tests for have always varied quite a bit.

But the C8s have been consistently been at least very good, and often excellent.

And for me, because it is so small and light, the C8 has been my own personal "Benchmark" for "Small" telescope performance. I define "Small" as being able to fit on a CG5 level mount.

And what I found is that if it fits in the field, I would far prefer to use a C8 over 4" or 5" refractor. Heck, since getting the EdgeHD, I don't think I have bothered taking out my 6" APO except during the summer (though to be fair, 90% of my observing is done with a C14).

Anyway, congratulations on your new scope. The C8 is the best all around "Small" scope that I think money can buy, and an excellent one should be a lifetime joy.

A lot of scopes used to come and go at my place, but I seem to have always had a C8 in the house. And if you are smart, you will avoid temptation to ever sell yours. An C8 with really excellent optics is something you just want to keep.

#8 Julio

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Posted 10 February 2013 - 01:30 PM

Thanks for the replies everyone, gfeulner as you describe the moons are perfect spheres with the planet itself filled with details. On 2-7-13 the eddy system following the GRS was fantastically intricate; Oval BA was very evident as well. I was quite amazed by this scope, field curvature is there but then again I only care at what is in the center of the FOV. And Ed I don’t plan on ever selling this scope, having owned several SCT, this one clearly being the best mechanically and optically no image shift whatsoever! I really hope Celestron found that magical formula to be able to homogeneously duplicate excellent scopes for us stargazers.

#9 Julio

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Posted 10 February 2013 - 02:02 PM

I think you are right on both counts: Celestron got its QC. under control and you got lucky. Those XLT coatings with what looks like a levitating secondary are something huh ? Glad to hear your success story.

Pete



Those XLT coatings are amazing, at the right angle the corrector disappears. I wonder if those XLT coatings are more durable than other competing coatings?

#10 azure1961p

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Posted 10 February 2013 - 04:45 PM

I hear they are actually very durable.

Pete

#11 Raginar

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Posted 11 February 2013 - 01:52 PM

The C8s are quite the scopes. I still love the Meade 'blue tubes' though.






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