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Equipment Discussions >> Cats & Casses

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Sarkikos
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Reged: 12/18/07

Loc: Scotophobe Maryland, USA
Re: My First SCT new [Re: azure1961p]
      #5640136 - 01/24/13 07:51 AM

Pete,

Quote:

Mike one of the clinchers for me on getting a C6 was Larry Carlinos review of his saying it was every bit as good as his Synta Mak of like sized aperture.




Is this the review?

Celestron C6-S Schmidt-Cassegrainian

Mike


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Sarkikos
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Re: My First SCT new [Re: Sarkikos]
      #5640142 - 01/24/13 08:00 AM

According to Larry Carlino's article, the C6 OTA weighs in at 8.6 lbs with the finder and visual back attached. My Bosma 6" Mak OTA - with no attachments - weighs 14.4 lbs! That's nearly 6 lbs more, an increase of 67% over the weight of the C6!

Mike


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t.r.
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Reged: 02/14/08

Loc: Upstate NY
Re: My First SCT new [Re: Sarkikos]
      #5640205 - 01/24/13 08:53 AM

Not just weight per say...mass! Thats where the thermal issues arise. I just hope that in practice, the C6 does cool quicker for you. I'm okay with the time mine takes. Not quick look, but still grab-n-go.

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Sarkikos
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Re: My First SCT new [Re: t.r.]
      #5640276 - 01/24/13 09:44 AM

I can deal with setting the C6 out for a half-hour or so to get the cool-down going. Many times I'll do that for the 90mm Mak anyway.

Mike


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Sarkikos
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Re: My First SCT new [Re: Sarkikos]
      #5640404 - 01/24/13 10:50 AM

Here are some comments on the performance of the C6 from Larry Carlino's review.

Comparing the C6 to the Orion 150mm Mak-Cass:

Quote:

These scopes are so close in revealing lunar and planetary detail that its difficult to choose one over the other both are very good.




Comparing the C6 to a Takahashi FS-102 fluorite APO:

Quote:

A Takahashi FS-102 fluorite APO refractor showed essentially the same level of detail [on Mars], but with superior contrast and slightly less brightness at the same magnification.




On the C6's light transmission:

Quote:

By counting stars in the beautiful Double Cluster in Perseus, I was able to determine that the C6-S provided about the same light grasp as the 5-inch Takahashi APO, and ,surprisingly, almost the same as the 6-inch achromat.



Celestron C6-S Schmidt-Cassegrainian

Mike


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t.r.
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Loc: Upstate NY
Re: My First SCT new [Re: Sarkikos]
      #5640790 - 01/24/13 02:08 PM

IME, those comments are spot on Mike. I compared the C6 to my Tak Sky 90, TMB 92L and C5 I used to own, to verify that indeed, the C6 showed more planetary/lunar detail and had much brighter images. In comparison to my old 4" Genesis, from memory, it shows the same level of detail with the nod for contrast going to the Genesis, but the C6 has the brighter image still. Now when it comes to comparing to my AP 130 GT, I can say this...I don't feel I'm missing a ton with my C6 and as my winter/grab-n-go scope, I'm very pleased with its ability to show a level of detail that satisfies much more than the 4" and 3.5" refractors and almost but not quite to the level of my 5"! The 130 still wins in contrast and brightness to my eye, but it is close enough that I can use the C6 and be satisfied when I do and not feel wanting like I did when I observed with the smaller instruments.

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RobertED
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Re: My First SCT new [Re: Rick Woods]
      #5640932 - 01/24/13 03:32 PM

Quote:

Ah! So you've finally given in and come over to the centrally-obstructed side!
Mwahaha!




...."one -of-us!, ...one-of-us!,....one-of-us!".....


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Sarkikos
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Loc: Scotophobe Maryland, USA
Re: My First SCT new [Re: RobertED]
      #5641297 - 01/24/13 07:19 PM

SCT Freaks!

Mike


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mattyfatz
Carpal Tunnel
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Reged: 12/27/06

Loc: Boise Idaho
Re: My First SCT new [Re: Sarkikos]
      #5642359 - 01/25/13 11:17 AM

"They are nice scopes but I wouldn't use the bobs knobs on them. Those are really for Newts which need constant alignment. Most SCT's never ever need collimation since they are rock solid from the factory. Once you install the bobs knobs on them, you will always find yourself adjusting them. This is a false positive and leads people to believe these types of scopes needs bobs knobs to Collimate. "

2nd


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coopman
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Loc: South Louisiana
Re: My First SCT new [Re: mattyfatz]
      #5642381 - 01/25/13 11:28 AM

I have them on my newt, but I'm scared to try & put them on my C6. If it ain't broke, don't fix it.

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BigC
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Reged: 09/29/10

Loc: SE Indiana
Re: My First SCT new [Re: Sarkikos]
      #5642384 - 01/25/13 11:30 AM

The comparison results and comments are not surprising considering the three .

I would expect scopes of equal effective aperture and decent optics to have near-identical results.


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Sarkikos
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Loc: Scotophobe Maryland, USA
Re: My First SCT new [Re: BigC]
      #5642545 - 01/25/13 01:03 PM

The C6 arrived today in good condition. It should have been left at my house two days ago, but we had to do a dance with UPS because HPS required a signature. To make a long story short, I went ahead and took a day off today to accept delivery. Anyway, it's Friday, and they were calling for snow. Win-win-win.

I checked the corrector, the primary, and the general condition of the scope. Everything looks great. No corrector sleeks, no scratches or fingerprints on the primary, the visual back is easy to screw off and on.

The C6 is surprisingly light. It doesn't seem any heavier than my ST80 with 2" Crayford! Compared to my 6" Mak, the C6 is like an empty paint can while the Mak is full of paint! These Cats always seem like paint cans or buckets to me. The C6 should be easy for grab-n-go. Not as easy as my little 90mm Mak, but probably easier than the ST80, and certainly easier than the 6" Mak.

Mike


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Sarkikos
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Re: My First SCT new [Re: Sarkikos]
      #5642567 - 01/25/13 01:13 PM

If the sky is clear and the seeing is OK tonight - it hasn't snowed yet - I might set up the C6 on my porch and check the optics and collimation by sighting Polaris.

It's a shame that the standard way to collimate these SCTs appears to be star testing. That's not really a very efficient way to go about it. I can collimate my Dobs and refractors anytime I want without leaving the house. I don't need to wait for a clear night and good seeing. I don't need to lug the Dob or refractor outside to collimate. If I do take them out to collimate, it's actually easier during the day than the night. And I don't have to take up precious time collimating on a night of good seeing.

Mike


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Sarkikos
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Re: My First SCT new [Re: Sarkikos]
      #5642594 - 01/25/13 01:27 PM

About Bob's Knobs ...

Seems like I've stirred up a hornet's nest by mentioning this topic. Judging from threads here in the Cats & Casses Forum, Bob's Knobs have been an ongoing controversy for awhile now.

I've put Bob's Knobs on all my Newts. For Newts, the Knobs make collimation MUCH easier and for me at least, make it easier to get a tight, secure collimation on the secondary. Many times I'll collimate with the Knobs here at home before travelling the 50 miles to my dark site. Most of the time the collimation is still tight when I get there. No problem at all.

My C6 has little Phillips collimation screws on the secondary. From my experience collimating Newts, I do not like using a Phillips screwdriver or allen wrench to adjust the secondary collimation. Even though I always collimate with the OTA horizontal, so the tool won't fall down onto the primary, I still worry about dropping it on the secondary.

At any rate, collimating with a tool is awkward. Bob's Knobs are much, much easier to use. I don't need a tool other than my fingers to turn them! For my smaller Newts, I can look in the Cheshire or autocollimator while I'm turning the Knobs. That makes collimation so easy it's almost a pleasure ... almost.

As far as Bob's Knobs not being tight enough or too tight on the SCT secondary, I think that would be mostly due to operator error. There is such a thing as "snug tight," folks.

But I'm in no hurry to install the Knobs. I'll check the factory collimation first.

One big point in Bob's Knobs favor is that Uncle Rod likes them!


Mike


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rguasto
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Reged: 11/18/10

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Re: My First SCT new [Re: Sarkikos]
      #5642650 - 01/25/13 01:55 PM

I don't think you need bobs knobs. The collimation screws have very little tension to them so striping the philips heads will not happen. In 2 years I have collimated my C6 2 times and each time collimation was off very little (and I star testevery time I observe). I can guarantee that if you replace the screws it WILL need to be collimated. As far as cool down time is concerned - images do not stabilize (in my experience) for close to 90 minutes. I have left it outside for 2 hours with the cover on and then put the dew shield on and discovered that it still needed to cool even more. Cool down times are faster with the corrector plate exposed. I use a surgical hair cap to cover the dew shield while the scope is cooling unattended. It's like a shower cap, but allows air in while keeping the corrector plate clean from dust and air-borne debris. Oh yeah; in cold weather the cover does not fit tightly when you pack-up for the night - in fact it will fall right off. I placed adhesive felt next to the tabs to remedy this.
-Rob


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Sarkikos
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Loc: Scotophobe Maryland, USA
Re: My First SCT new [Re: rguasto]
      #5642736 - 01/25/13 02:47 PM

Rob,

Quote:

I don't think you need bobs knobs. The collimation screws have very little tension to them so striping the philips heads will not happen. In 2 years I have collimated my C6 2 times and each time collimation was off very little (and I star testevery time I observe). I can guarantee that if you replace the screws it WILL need to be collimated.




No, I don't need Bobs Knobs. I didn't need them for my Newts, either. But they would make it easier - and safer - to collimate the SCT, as it does for my Newts. I fully expect the collimation to be off once I install the Knobs. Most of my experience has been with Newts. Collimation is not a big deal for me.

Mike


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Sarkikos
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Loc: Scotophobe Maryland, USA
Re: My First SCT new [Re: rguasto]
      #5642743 - 01/25/13 02:52 PM

Rob,

Quote:

Cool down times are faster with the corrector plate exposed. I use a surgical hair cap to cover the dew shield while the scope is cooling unattended. It's like a shower cap, but allows air in while keeping the corrector plate clean from dust and air-borne debris.




Yes, I was concerned about leaving the corrector plate exposed for cool-down, but it does make sense to do that. Where can I get a surgical hair cap to fit my C6? ... I mean, besides going to a hospital and asking around for one. I don't do that kind of thing.

Quote:

Oh yeah; in cold weather the cover does not fit tightly when you pack-up for the night - in fact it will fall right off. I placed adhesive felt next to the tabs to remedy this.




I'd be concerned about the adhesive coming undone and ending up on the corrector plate. We have a lot of dew in my area. But thanks for the heads up about the loose cover.

Mike


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Sarkikos
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Loc: Scotophobe Maryland, USA
Re: My First SCT new [Re: Sarkikos]
      #5642910 - 01/25/13 04:20 PM

It's snowing. I don't think I'll get a chance to check the scope's collimation tonight.

Mike


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Sarkikos
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Re: My First SCT new [Re: Sarkikos]
      #5644559 - 01/26/13 02:57 PM

It's not convenient to place a Christmas bulb in a tree and collimate off that during the day. I live in a condo and do not have a backyard. Neighbors might find it odd to see a middle-aged man shimmy up a tree in the common area to put up a Christmas ornament.

I looked around for a glinty object that I could point the C6 at from my house. First I tried the shiny edge of a metal exhaust vent pipe on a roof in the court behind me. Then I tried the glint off the fender of a car. I used a BGO 18 (83x, 14x/inch), BGO 7 (214x, 36x/inch), BGO 6 (250x, 42x/inch) and XO 5.1 (294x, 49x/inch). The shadow of the secondary appeared concentric at all these magnifications, and the image seemed the same on both sides of focus.

This was enough to let me know that my C6 is at least reasonably well collimated. Maybe neither glint was small enough or the sun wasn't bright enough or both, but I couldn't get a good view of diffraction rings for a thorough test.

Mike


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coopman
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Re: My First SCT [Re: Sarkikos]
      #5644667 - 01/26/13 04:17 PM

Glad that you got your new scope OK, Mike. The C6 is so lightweight that many who handle it might think that it feels more like a toy and not a decent quality telescope. I still wish that they'd put some sort of handle on these things for the times when you're putting it on and off the mount. I'm always afraid that I'm going to drop it.

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