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New AT 6" and 8" Classical Cassegrain

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#1176 TerryB

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Posted 10 October 2020 - 06:38 PM

TerryB

 

Questions:

#1-So were you trying to focus on a star or a distance object during the day?

#2-You had 4" of rings, plus focuser, plus 2" diagonal which is another 4" and you still needed 4" out of diagonal to reach focus?

 

Mike

#1.  Both.  My first attempt was at night and I saw nothing, so next day set up during the day to try distant objects.

#2.  Sadly, true.



#1177 Thandal

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Posted 10 October 2020 - 06:58 PM

@TerryB;  I'm not at all sure what you're doing/describing.  frown.gif

 

I have owned both the 6" and the 8" Orion CC telescopes and, as described in the owner's manual, visual observing requires using the 1" extension ring to reach focus with most eyepieces.  Those doing imaging don't generally need to use the rings because they already have a longer optical path to their camera's sensor/film. 

 

I observe using a standard star diagonal (2" barrel) and both 2" and 1.25" eyepieces ranging from 6mm to 40mm.  Sometimes (e.g. when using a Barlow) I might have to add a second 1" extension ring, (or use the 2" ring instead) but I never needed more than that.

 

Your set-up is definitely not right, but from the information provided can't tell how/why.



#1178 Spacedude4040

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Posted 10 October 2020 - 07:07 PM

#1.  Both.  My first attempt was at night and I saw nothing, so next day set up during the day to try distant objects.

#2.  Sadly, true.

Your distant object needs to be a mile or two away. 

Try focusing on the moon for starters then let us know.

Mike


Edited by Spacedude4040, 10 October 2020 - 07:50 PM.


#1179 TerryB

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Posted 10 October 2020 - 07:11 PM

@Mike.  Thanks, I'll do that at the first opportunity.



#1180 Bomber Bob

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Posted 10 October 2020 - 10:22 PM

Send It Back.  



#1181 glend

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Posted 11 October 2020 - 01:59 AM

Send It Back.  

Probably too late for that. I believe he bought it from TS in Germany and the EU has a standard return period. He then held the scope for some time before discovering the problem.  Certainly communicating with Wolfie at TS would be a good idea, you never know what he might suggest. Unfortunately vendors can not warranty shipping and handling problems.  Best bet is likely getting help here to resolve it, if it is simply a collimation issue. As to the loose baffle tube, they simply screw onto the centre collar and are not actually structural in terms of mirror support. 

 


Edited by glend, 11 October 2020 - 02:01 AM.


#1182 quilty

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Posted 11 October 2020 - 03:31 AM

Hi Terry,

 

You've got two possiblities. 1. Sending back. I think TS won't refuse, if they do let us know.

 

2. Keep it and try to get straight into the things. This scope is a very fine demonstration tool for its assembly is so easy and obvious. You can dismantle everything and reassemble without the danger of irreversible damage. These scopes seem to have some issues described in the 50 foregoing pages but your scope might be a very special one we all could possibly learn from it. As you described until now with a wiggling primary baffle (it is not the finderscopesmile.gif ) I'm afraid your next logigal step would be removing the buttplate from the tube which is again very easy by just unscrewing 6 (or 8? for the 8") small screws on the rear circumference and check if the center baffle is moving or the mirror can be turned like an old music record. And pics from any position might help. Disassembly, taking pics and reading dimensions can be done, unlike stargazing, without a cloudy sky in a cosy room at daylight smile.gif  No big thing, but if that's not your business, back to 1.

 

But if you continue and it really turns out that you get sort of an image way behind extension rings, diagonal and eyepiece threre're two possibilities: The distance between the mirrors is too short. (1 mm short needs  about 16 mm more backfocus). spacedude can tell the exact data I guess for I own just the 6 inch scope. 

If you find the mirror distance to be correct and you still find an image at a way too long distance one or both mirrors are mismatched. This would be then your last exit chance for another scope, I suppose.

 

 

I was just considering my experiences and mentions in this thread and advising along propability

 

loose mirror - often

odd assembly - none

wrong or mismatched mirror - none


Edited by quilty, 11 October 2020 - 04:19 AM.


#1183 Bomber Bob

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Posted 11 October 2020 - 07:44 AM

I'd be surprised if TS refused a return of an obviously defective new scope.  I've never had an issue dealing with them.

 

The RISK in DIY work on a brand new scope is accidental damage.  Stuff happens, and would void the warranty.  I've restored a lot of old scopes, but I've never had to immediately start troubleshooting a brand new scope.

 

But Yes!  Pix of this scope would help us offer advice.


Edited by Bomber Bob, 11 October 2020 - 07:46 AM.


#1184 Spacedude4040

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Posted 11 October 2020 - 08:31 AM

OK my bet is there is nothing the matter with his scope. I believe he is a novice astronomer as he is calling the primary light baffle a finder scope. Hey we all gotta start some where. The mistake he might have made is he tried to focus on something to close. Cassegrain need to be focused at infinity or else it throws the focus point way out of wac!

I think he needs to get fimalar with the scope and he will be fine.

The moon should be his first target.

Mike


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#1185 Thandal

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Posted 11 October 2020 - 10:18 AM

OK my bet is there is nothing the matter with his scope. I believe he is a novice astronomer as he is calling the primary light baffle a finder scope. Hey we all gotta start some where. The mistake he might have made is he tried to focus on something to close. Cassegrain need to be focused at infinity or else it throws the focus point way out of wac!

I think he needs to get fimalar with the scope and he will be fine.

The moon should be his first target.

Mike

 

I agree with the above, and would add that depending on the eyepiece it's easy to see "nothing at all" due to unfamiliarity with proper eye relief and the "kidney bean" effect.

 

Practice, practice, practice.

Ideally with a more experienced observer along side to answer questions and offer advice.  waytogo.gif


Edited by Thandal, 11 October 2020 - 01:40 PM.


#1186 TerryB

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Posted 11 October 2020 - 01:32 PM

Well, hat's off to Mike for suggesting I make the Moon my next target. waytogo.gif Problem solved!

 

The moon was not available the first night I tried this scope.  I have a restricted view of the sky to the SE, and had only the relatively dim stars of Pegasus to aim at then.  I'm not a total newb at star-gazing and rely on star-hopping for navigation with my refractors.  I have a telrad and small refractor set up on my dual-saddle alt-az mount that can act as finder scopes, but I needed to get the CC8 to focus first before I could sync them., hence my trouble.

 

Clearly the lesson here is, as Mike suggested, to make Luna your target if you have any trouble finding stars.  If you have to wake up at 4:30 AM to do it, then that's what you do.  My mistake was thinking I could manage without it.

 

Oh, and thanks to Mike for putting a proper name on that 'finderscope' (not my word, btw): primary light baffle.

 

With luck, I can now look at the night sky rather than at my telescope.  Collimation to come, though, and yes, I have Mike's guide bookmarked!

 

Clear skies, everyone.



#1187 jgraham

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Posted 11 October 2020 - 04:27 PM

A quick thought on collimation... aligning the secondary is easy peasy. However, I would be very reluctant to touch the primary unless I absolutely had to.

 

Tread with caution...



#1188 quilty

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Posted 12 October 2020 - 04:33 AM

This is the plot of a classic happy end. Problems resolved into nothing.



#1189 Spacedude4040

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Posted 12 October 2020 - 06:53 AM

@TerryB
Sorry for calling you a newbie lol, I guess I should have looked at your profile. But in my defence I had images of Turkey and Ham dancing in my head.
Funny how twenty of us can read something and may have twenty different interpretation of what we read.
Glad your problem is solved and your good to go.
Mike

#1190 TerryB

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Posted 12 October 2020 - 01:54 PM

@Mike, no worries.  We're lucky to have you here, sharing what you know about these cassegrains.  @Quilty, I admire your skepticism toward marketing hype, and especially your courage in tearing these scopes apart to see what makes them tick!  I'd never get it back together again in anything close to working order grin.gif



#1191 Bomber Bob

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Posted 12 October 2020 - 04:48 PM

I'm glad you didn't have to return the scope, but... What's the close focus limit on the AT 6" Cass?  I have no problem focusing my 6" F20 on the tops of oak trees about 200 ft away, and without extenders -- just the 4" travel on its R&P focuser + a 1.25" prism diagonal.  I sight my finders during the day, using a street light less than 1/4 mile away, and no near-focus issues.  



#1192 TerryB

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Posted 12 October 2020 - 10:08 PM

Bomber Bob, I have the 8", so can't really comment on the min. focus limit of the 6".  I still don't really know what the min. focus limit is for the 8", either.
 

I'm glad you didn't have to return the scope, but... What's the close focus limit on the AT 6" Cass?  I have no problem focusing my 6" F20 on the tops of oak trees about 200 ft away, and without extenders -- just the 4" travel on its R&P focuser + a 1.25" prism diagonal.  I sight my finders during the day, using a street light less than 1/4 mile away, and no near-focus issues.  

 



#1193 quilty

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Posted 13 October 2020 - 04:23 AM

I'm glad you didn't have to return the scope, but... What's the close focus limit on the AT 6" Cass?  I have no problem focusing my 6" F20 on the tops of oak trees about 200 ft away, and without extenders -- just the 4" travel on its R&P focuser + a 1.25" prism diagonal.  I sight my finders during the day, using a street light less than 1/4 mile away, and no near-focus issues.  

That's what I'm always saying. A 2 m scope should bear a 4 inch long focusser at least. Second possibility is the extension rings.

On the other hand, a 4 inch focussing tube might be annoying in the scope tube or outside

My 6" CC has a 1.5 inch long focusser, so I need an extension ring (1 inch)

Once I tried an artificial star (a polished steel ball in the sun) in my backyard and needed all extensions (4 inch) plus 2" diagonal and still was a bit short at 35 m. That's the big advantage of a focussing primary, you can focus anything.

Now, with the 1 inch extension and 2" diagonal focussing starts at about 160 m and reaches out to 8 horizontal



#1194 Garyth64

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Posted 15 October 2020 - 07:29 PM

I tried to read as much as I could in this thread, because I am interested it getting one of these/those 8" f/12 CC's.

 

Am I right to think that GSO, Orion, and Astro-Tech, all are selling these scopes? And optically they are all the same?

 

If so, I like the glossy black.  I like the two mounting plates.  I like that there isn't a corrector lens.  I like that the focuser doesn't move the primary.

 

I like the f/12 focal length.  So that narrows it down to two.  Do I want the Orion logo, or the GSO logo?

 

  If  they were available now, I would be buying one now.


Edited by Garyth64, 15 October 2020 - 07:31 PM.


#1195 Thandal

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Posted 15 October 2020 - 07:34 PM

<snip>
Am I right to think that GSO, Orion, and Astro-Tech, all are selling these scopes? And optically they are all the same?

<snip>

I like the f/12 focal length.  If  they were available now, I would be buying one now.

 

Yes, GSO is the manufacturer for all of these and allows (select) retailers to brand them.

And yeah, looks like about a month wait ("expected ship date 11/13/2020") for these OTAs from Orion.  Don't know about other sources...


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#1196 quilty

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Posted 16 October 2020 - 04:21 AM

I like how it looks

 

Attached Thumbnails

  • DSCF7801.JPG

Edited by quilty, 16 October 2020 - 04:26 AM.

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#1197 astronoob123

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Posted 16 October 2020 - 04:43 AM

I like how it looks

The setup looks great. what mount is that?flowerred.gif



#1198 jgraham

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Posted 16 October 2020 - 10:30 PM

I spent this evening star-hopping with my CC8 on an LXD75 and Sky Safari via SkyFi. Using a 2" Meade 56mm Super Plossl gave a very comfortable field of view and it was easy to crank up the magnification using 1.25" Meade UWA eyepieces. Wonderful scope!
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#1199 quilty

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Posted 17 October 2020 - 03:50 AM

The setup looks great. what mount is that?flowerred.gif

Neq3 by Skywatcher, nothing special

 

And the four simple 1.25" golden edge 66° eyepieces do well, I think at any scope. Instead of that big 56mm 52° eyepiece I purchased a short refractor 102/460 which proviedes quite a different view through the very same eyepieces. But my first idea was those long big 2 inch eyepieces as well. On a fast, lightweight fotographic mount, no need  for an eq mount at that low power. This combination allows to watch all kind of standard objects except all the advanced, dim ,big, clear sky ones. 


Edited by quilty, 17 October 2020 - 04:18 AM.


#1200 Bomber Bob

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Posted 17 October 2020 - 03:37 PM

And the four simple 1.25" golden edge 66° eyepieces do well, I think at any scope.

 

My Cass is like my LONG achromatics in that respect:  No need to use expensive / complicated eyepieces.  The glass quality matters more than the designs, and simple Erfles, Kellners, Orthoscopics, & Plossls yield sharp views.


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