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Equipment Discussions >> Cats & Casses

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Ed Holland
Pooh-Bah


Reged: 06/16/10

Loc: San Jose, CA and Oxford, UK
A well tuned C8 on Jupiter
      #5530970 - 11/20/12 08:21 PM

Preaching to the choir this, I know, but still:

Last night was the first opportunity I have had, in nearly 12 months of ownership, to set my C8 upon glorious Jupiter. Previous viewing has been with the 5" refractor or 127mm(118) Mak. Both are of decent, if not outstanding quality, but it is to be admitted that my experience in this matter is limited.

All I can say about the C8 is WOW! despite very variable seeing, I was delighted at the detail and contrast that was evident at the eyepiece. I can't wait for a really steady night. Focussing was very crisp, without ambiguity, and when the sky co-operated Jove's disc possessed a hard edge against a dark night sky and fine detail in the cloud bands. I'm truly impressed with the optics. This performance also demonstrates the value - mentioned recently in other threads - of ensuring correct, precise assembly of all OTA elements - the 'scope was a wonky astigmatic mess when first received even after attempts at secondary collimation.

I do hope the weather co-operates for the next convenient shadow transit visible from this part of the world.

The instrument really seems to be a winner, a great example of its kind, and I couldn't be more pleased with its performance


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Asbytec
Guy in a furry hat
*****

Reged: 08/08/07

Loc: La Union, PI
Re: A well tuned C8 on Jupiter new [Re: Ed Holland]
      #5530983 - 11/20/12 08:31 PM

Ed, Jupiter has been knocking my socks off. In fact, I think there is a pair over there. I am happy you're out in the elements spying on the King.

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Mitchell Duke
Post Laureate
*****

Reged: 04/22/08

Loc: Georgia
Re: A well tuned C8 on Jupiter new [Re: Asbytec]
      #5530986 - 11/20/12 08:34 PM

Great! How did you align the optics?

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Starman27Moderator
Post Laureate
*****

Reged: 01/29/06

Loc: Illinois, Iowa
Re: A well tuned C8 on Jupiter new [Re: Asbytec]
      #5530989 - 11/20/12 08:36 PM

Ed,

Great! Jupiter is a wonderful sight. Looks like you have a fine telescope. Enjoy.


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Eddgie
Postmaster
*****

Reged: 02/01/06

Re: A well tuned C8 on Jupiter new [Re: Ed Holland]
      #5531067 - 11/20/12 09:20 PM

The C8 is an often under-estimated telescope.

If the optics are excellent (and many of them are) it can produce very satisfying planetary images.

Happy to hear your efforts were rewarded with some excellent viewing.


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charen
Carpal Tunnel
****

Reged: 05/28/05

Loc: New Zealand
Re: A well tuned C8 on Jupiter new [Re: Eddgie]
      #5531105 - 11/20/12 09:41 PM

I regret selling my Classic Orange C8 many years ago - some of the best planatary images I have ever had where though those optics. For some reason that one gave better images then more modern C8ís with superior coatings. A well collimated, well cooled C8 really is a great 'all round', portable, cost effective scope.
Donít forget the Celestron C8 was the scope that helped revolutionize amateur astronomy in the 1970ís and has been Celestronís best selling scope for decades.

Chris


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doug mc
super member
*****

Reged: 03/21/09

Loc: Tamborine Mountain Australia
Re: A well tuned C8 on Jupiter new [Re: charen]
      #5531178 - 11/20/12 10:24 PM

I am being converted to SCTs. After years observing jove with 6,8,and 10 inch Synta and GSO newts, 4,5, and 6 inch acro refractors from Synta, my latest scope a Celestron C6 SCT gave better images of the planet than all of them. It star tests nigh perfect to my eyes, and would give my 8 inch f/6 newt with a good Parks mirror a real chalenge.

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Dixie
super member


Reged: 03/30/06

Loc: UK Latitude 53.3 north
Re: A well tuned C8 on Jupiter new [Re: doug mc]
      #5531564 - 11/21/12 06:18 AM

We had a night of very good seeing in Scotland over the weekend allowing me to get a decent collimation on my C8 - what a great view. It was the best I've seen Jupiter look in 30 years of observing. Put in the Denk standards it was knock your socks off time. I've owned the scope since 1994 and my love affair grows each year. Cooled and collimated it's an absolutely great scope - and one I can carry in one arm.

Edited by Dixie (11/21/12 06:35 AM)


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Steve Darden
professor emeritus


Reged: 07/29/07

Loc: Woodstock, GA
Re: A well tuned C8 on Jupiter new [Re: Dixie]
      #5531606 - 11/21/12 07:16 AM

Ed, what magnification were you using?

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thomas68
professor emeritus


Reged: 01/25/11

Loc: North west Indiana
Re: A well tuned C8 on Jupiter new [Re: Steve Darden]
      #5531616 - 11/21/12 07:33 AM

Ed, I went through the same thing.Started with my 127 mak first real catastrophic, great little telescope.Bought a C8 XLT and never looked back! First time on Jupiter was amazing!

Enjoy,Tom


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t.r.
Post Laureate
*****

Reged: 02/14/08

Loc: Upstate NY
Re: A well tuned C8 on Jupiter new [Re: thomas68]
      #5531750 - 11/21/12 09:17 AM

I've gone full circle. Started with a small refractor and my first "real" scope was the C8. Got excited about the images in the apo refractors and touted them for many years and still do. A few years ago, wanting more aperture at reasonable cost, I have come back to SCTs with a C11XLT. With this scope, I saw the small white ovals in the polar regions of Jupiter that alluded me for decades with the smaller apos. I now have my eye on a C14. I will always have an apo for the crisp, sharp, wide-field and high contrast views. But now, I will also always have a large SCT in the stable to compliment the apo as well!

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Eddgie
Postmaster
*****

Reged: 02/01/06

Re: A well tuned C8 on Jupiter new [Re: t.r.]
      #5531794 - 11/21/12 09:37 AM

Quote:

I will always have an apo for the crisp, sharp, wide-field and high contrast views.




This has been my message for years now. Where APOs excel is in their superb off axis performance. People don't beleive me (or think I am crazy) when I tell them my primary use of my 6" APO is low power wide field work.

For the center of the field (Planets) it is all to easy to get better performance with a bigger scope. But getting a really wide field view that is free from coma and with a reasonably flat field is better done with a small refractor.

The C8 is a nice compromise though. Most worthwhile targets will fit into the field of a C8 with a 35mm Pan, and it will show them better than a smaller refractor, but still with some come.

And that is why I fell in love with the EdgeHD 8. Equal to to the very best refractors in off axis performance, and better than smaller refractors at the center of teh field.

C8s are excellent though, and as I get older and less inclined to want to mess with the big stuff, I seem my EdgeHD 8" taking a primary role in my observing.

But if the EdgeHDs had not come along, it would have been a standard C8, and I would never have felt bad about it.

The trick to being really happy with a C8 is to learn to star test properly, and buy and sell a few until you get one with really excellent optics. If the optics are excellent (and reasonable percentage of them are), they can be fine performers.


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GeneT
Ely Kid
*****

Reged: 11/07/08

Loc: South Texas
Re: A well tuned C8 on Jupiter new [Re: Ed Holland]
      #5531924 - 11/21/12 10:45 AM

I would be interested in an A B comparison of the views of Jupiter between your 5 inch refractor and your 8 inch SCT.

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Ed Holland
Pooh-Bah


Reged: 06/16/10

Loc: San Jose, CA and Oxford, UK
Re: A well tuned C8 on Jupiter new [Re: GeneT]
      #5532053 - 11/21/12 11:36 AM

To Steve Darden:
On the night in question, magnifications up to 200x were used - as much as was useful given the disturbed atmosphere.

To whduke
Achievement of good alignment involved - centering the corrector to place the secondary at the centre of the fromt housing. Then I discovered that the rear cell was tilted on the tube - somewhat loose actually. I corrected the cell tilt by trial and error, using the "concentric reflections" method as a gauge. This approach can be very accurate if one is careful about viewing postion. Lastly, a final fine adjustment of the secondary brought about a nice star test.

The scope fits my needs very well, and does so on a modest budget.

Gene:
I'll try and do an A/B with the 5" and come back to the thread. It's a bit tricky, since I've only one mount capable of carrying these instruments... a lot of juggling involved


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saemark30
Pooh-Bah


Reged: 02/21/12

Re: A well tuned C8 on Jupiter new [Re: Ed Holland]
      #5532129 - 11/21/12 12:11 PM

What rear cell, you mean the primary mirror has a cell?

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Ed Holland
Pooh-Bah


Reged: 06/16/10

Loc: San Jose, CA and Oxford, UK
Re: A well tuned C8 on Jupiter new [Re: saemark30]
      #5532227 - 11/21/12 12:58 PM

Yes, the rear casting, assembly, or whatever you want to call it, that comprises the baffle tube, primary mirror and focus mechanism.

I suspect inexperienced hands had tinkered with the assembly - the corrector & secondary were not in the typical orientation with respect to the main tube... Also possible is that the thump(s) it received in transit, severe enough to damage the corrector housing, also knocked the rear assembly loose from the tube. Either way, this was all fixable with care and a methodical approach.


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w orchid
Pooh-Bah


Reged: 04/23/07

Loc: Tampa, Fl
Re: A well tuned C8 on Jupiter new [Re: Ed Holland]
      #5532405 - 11/21/12 02:39 PM

A well collimated, cooled down C8 will produce outstanding results.

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dscarpa
Post Laureate
*****

Reged: 03/15/08

Loc: San Diego Ca.
Re: A well tuned C8 on Jupiter new [Re: Ed Holland]
      #5532427 - 11/21/12 02:52 PM

If SCTs aren't good for lunar-planetary my C-9.25 hasn't heard the news. With very good seeing last night the amount of detail visable on Jupiter with a oh so sharp image using my first time in the SCT 12 Delos for 230X and had it awhile 10 XW for 270X was incredible! Ditto for the Moon with the Delos alone and in a 1.5X Siebert barlow for 350X! My cat has a Crayford so it comes in 20X-30X higher than stock. I keep collimation spot on. David

Edited by dscarpa (11/21/12 04:25 PM)


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Ed Holland
Pooh-Bah


Reged: 06/16/10

Loc: San Jose, CA and Oxford, UK
Re: A well tuned C8 on Jupiter new [Re: dscarpa]
      #5532754 - 11/21/12 06:13 PM

Oh, I'm just happy because I feel as if I've finally reached the end of a long journey to see what I was getting with another, different, bigger telescope. Whilst I was very disappointed with my starting point - a scope so nearly ruined in transit, it turns out to have been an enjoyable and worthwhile effort to put things right.

The C8 does seem like a very capable scope - it is great that a modest outlay can put this sort of capability for light gathering and resolution in the hands of so many of us. And I can store it easily without upsetting domestic harmony.

Now many journeys can be enjoyed amongst the Solar system and beyond


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Dan McConaughy
sage


Reged: 11/11/06

Loc: LA
Re: A well tuned C8 on Jupiter [Re: Ed Holland]
      #5533525 - 11/22/12 08:33 AM

I had an 8" D&G refractor, but the planetary views were never as good as in my C14, given the seeing.

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