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Equipment Discussions >> Cats & Casses

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elmiko
member


Reged: 07/28/09

Loc: Arizona
Re: New C8s - Cheap! new [Re: jrbarnett]
      #5753124 - 03/24/13 01:36 AM

Jim, which alt az mount are you using? I've got the Vixen star guy. I use it on some of my refractors, still have not put the C-8 on it yet. Speaking of fr ff I bought the Meade 6.3 fr. I tried using it on the Celestron, but can't achieve focus with it. Any idea why?

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palmer570
super member
*****

Reged: 09/04/12

Loc: Scranton, Pennsylvania
Re: New C8s - Cheap! new [Re: elmiko]
      #5753270 - 03/24/13 04:49 AM

I just tried a 6.3 on my C8 and it seemed like it wasn't going to come into focus but eventualy did. I had a motofocus on it though and didn't want to run it for long periods of time and was focusing the wrong way at first so not sure how far off it was at the start or how fast the moto turns at top speed.

What do you have attached after the fr/ff?


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KeithC
super member


Reged: 08/23/06

Loc: Atlanta GA
Re: New C8s - Cheap! new [Re: jrbarnett]
      #5753533 - 03/24/13 10:05 AM

Jim,

What do you mean when you say 50% of them have been "soft" optically and the other 50% had "good optics"? What is the difference between those two extremes? Is it obvious visually or merely subtle? I have only looked through one C-8 and that was at an outreach Monday night. So I have little to compare your comments against in trying to understand what you mean.


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elmiko
member


Reged: 07/28/09

Loc: Arizona
Re: New C8s - Cheap! new [Re: palmer570]
      #5753575 - 03/24/13 10:24 AM

Hi palmer750, I tried with a gso 2" diagonal and with a 2" nose piece on my dslr Canon t2i. Niether one could achieve focus.

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elmiko
member


Reged: 07/28/09

Loc: Arizona
Re: New C8s - Cheap! new [Re: elmiko]
      #5753582 - 03/24/13 10:26 AM

I still haven't tried it with my Meade 10 sct though.

Edited by elmiko (03/24/13 10:27 AM)


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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: New C8s - Cheap! new [Re: elmiko]
      #5754953 - 03/24/13 08:59 PM

Hi elmiko.

I am using a DSV-3 with the C8.

Here's the mount with an AT111EDT on it. I didn't take a picture of the C8 on the mount unfortunately, but the mount has zero problems with the C8 OTA.



Regards,

Jim


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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: New C8s - Cheap! new [Re: KeithC]
      #5754986 - 03/24/13 09:14 PM

Hi Keith. By "soft" optics I mean that, no matter how well collimated and how well acclimated, the quality of star images and planetary images in the scope remained bloated in the case of stars and smudged in the case of planets. By "good" optics, I mean the converse - that when well collimated and cooled the scope produced reasonably crisp pinpoint stellar images and sharply rendered planetary detail. The poor examples had significantly unequal intra- and extra-focal diffraction patterns. The good examples did not have perfect symmetry, but were much, much closer to matched inside and outside of focus.

Were there other telescopes present besides the C8? If so, did you happen to observe the same target through the C8 and one of the other scopes at approximately the same magnification? What did you think about it's image versus the other scope's? That's probably the only way casually you'd be able to form an opinion about that particular C8 versus other types of scopes or other SCTs if more than one are in the field.

Regards,

Jim


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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: New C8s - Cheap! new [Re: palmer570]
      #5755002 - 03/24/13 09:22 PM

Hi palmer. Last night I mounted the stock 1.25" visual back aft of the FF/FR and used a 1.25" GSO mirror diagonal.

Regards,

Jim


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elmiko
member


Reged: 07/28/09

Loc: Arizona
Re: New C8s - Cheap! new [Re: jrbarnett]
      #5755030 - 03/24/13 09:37 PM

Jim that is one sweet set up!

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Julio
sage
*****

Reged: 01/18/07

Loc: Pembroke Pines ,FL
Re: New C8s - Cheap! new [Re: elmiko]
      #5755141 - 03/24/13 10:42 PM

I just recently purchased one of the orange tube C8. I posted a while back about mine, intra focal and extra focal images are very similar and the details on Jupiter are amazing when seeing is good. I can always see 6 stars on the trap, Jupiter looked great easily showing detail within the GRS as well as eddies adjacent to GRS. This particular orange tube C8 outperforms the Intes MAK and the 4"APO.

Edited by Julio (03/24/13 11:01 PM)


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KeithC
super member


Reged: 08/23/06

Loc: Atlanta GA
Re: New C8s - Cheap! new [Re: jrbarnett]
      #5755238 - 03/24/13 11:48 PM

Thank you for the explanation Jim. There were 4 other scopes. A 6" Meade SCT and three refractors, a 90mm achro, 102mm apo and a 6" Meade ED. The C-8 had a soft image until it cooled, then the images were crisp, eventually rivaling the image in the large refractor. It bothered me that I could not seem to focus the 6" SCT to the same level of clarity as the 8". I was a little wary of asking comparison questions for fear of offending people. I want to expand my thinking without insulting others so I am not so sure how to word things sometimes.

Anyway, it was a good experience for me. I was afraid to get out of the car at first but those outreach people were a very nice gracious group of men and women. Pleasure to meet them, so glad I went. Some very nice people here as well.

Keith


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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: New C8s - Cheap! new [Re: KeithC]
      #5755284 - 03/25/13 12:21 AM

Excellent, Keith.

What makes determining the quality of an SCT under casual observing circumstances difficult is that SCTs take a long while to adjust to ambient temperatures compared to other designs (inch per inch), and also SCTs use extremely fast mirrors (~f/2) so collimation is absolutely critical to decent "crisp" performance in the design. As often as not you'll find SCTs at star parties to be slightly out of collimation. This is less of a big deal for DSOs, but for planets and tight doubles, it's the death knell of their performance.

Your approach is a good one. Use, see, learn and don't judge too quickly.

Regards,

Jim


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KeithC
super member


Reged: 08/23/06

Loc: Atlanta GA
Re: New C8s - Cheap! new [Re: jrbarnett]
      #5755672 - 03/25/13 08:40 AM

Jim,

Thank you the explanations and the encouragement!

Keith


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Alterf
professor emeritus
*****

Reged: 04/07/06

Re: New C8s - Cheap! new [Re: KeithC]
      #5758646 - 03/26/13 04:56 PM

I bought one of these C8s, too. It is the first SCT I have ever used about which I have no complaints at all. The optics are sharp and have retained collimation for months so far, the focuser is just right, and I have experienced no image shift. The tube is light in weight, and I really like the metallic orange. I have enjoyed the views through it very much. It is does exactly what I hoped it would.

Val


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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: New C8s - Cheap! new [Re: Alterf]
      #5758681 - 03/26/13 05:13 PM

Excellent Val.

Also kudos on your successful March 5 star party. Melding wifi and tablets with GOTO is a great tool for teaching.

Regards,

Jim


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Alterf
professor emeritus
*****

Reged: 04/07/06

Re: New C8s - Cheap! [Re: jrbarnett]
      #5759419 - 03/26/13 11:46 PM

Thanks, Jim. For some of the students, "what app do you use to control the scope" was the most interesting question. Others just hung around the scope and wouldn't leave. It was a real astronomical highlight for me. I hope it happens again soon.

Val


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mark379
sage
*****

Reged: 02/07/09

Loc: New Jersey
Re: New C8s - Cheap! new [Re: elmiko]
      #5792110 - 04/11/13 10:57 AM

Jim, You're right. I've owned quite a few sct's an some have less than average optics, while others have good optics. I finally settled on a c8 that is as close to perfect as I can find. The only other one that matched this mid 90's black tube was my friend's new nexstar orange tube. They are GREAT deal indeed. The ones being sold by by high point now are left over OTA's from the big sale 2 years back when the nexstar was $999.00. Afterward they split up the remaining mounts and tripods to the deal they have now.

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Daud
sage


Reged: 08/05/06

Loc: AZ, Scottsdale
Re: New C8s - Cheap! new [Re: mark379]
      #5792373 - 04/11/13 01:23 PM

That means that the $999 was a better deal...
I noticed that the combined price of the separated OTA and mount comes to the standard street price..

Quote:

Jim, You're right. I've owned quite a few sct's an some have less than average optics, while others have good optics. I finally settled on a c8 that is as close to perfect as I can find. The only other one that matched this mid 90's black tube was my friend's new nexstar orange tube. They are GREAT deal indeed. The ones being sold by by high point now are left over OTA's from the big sale 2 years back when the nexstar was $999.00. Afterward they split up the remaining mounts and tripods to the deal they have now.




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Geo.
Carpal Tunnel
*****

Reged: 10/01/08

Loc: Upstate NY
Re: New C8s - Cheap! new [Re: Husbyggarn]
      #5792571 - 04/11/13 03:03 PM Attachment (12 downloads)

Quote:

God, you guys are lucky, in Sweden it costs 1400$!
Even so, i can see myself owning one in the future...



Well, you've friends (and probably cousins) here.

GGPa from Karlskrona GGMa from Malmo. GGpa in the center with his parents (CA 1865).


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mark379
sage
*****

Reged: 02/07/09

Loc: New Jersey
Re: New C8s - Cheap! new [Re: Geo.]
      #5793384 - 04/11/13 10:07 PM

You're right. They seem to be at the standard price separated...

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