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Celestron C8 vs. C6

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#1 paulsky

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Posted 12 August 2014 - 11:10 AM

        Hello,
Someone has been able to compare face to face an SC telescope of 6 "with an 8"?
There is not much difference in terms of: weight, volume, manageability and luminosity-resolution in the images.?
greetings and thanks
Paul



#2 KJL

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Posted 12 August 2014 - 12:01 PM

Oh man, normally I hate to do this -- and I know the CN search function is a bit twiddly -- but seriously? On the first page of results alone are comparisons of DSO and imaging performance, compactness, cooldown, and even airline transportability.

 

If I've misunderstood your (rather general) question, I apologize profusely. But I think you'll find everything you need from those highly detailed and well-commented threads.


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#3 Sarkikos

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Posted 12 August 2014 - 01:04 PM

Not everyone knows how to Google using the site: function. But teach a man to fish ... :ubetcha:

 

:grin:

Mike



#4 rmollise

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Posted 12 August 2014 - 07:47 PM

I'll make it short and sweet:  the C8 delivers nearly twice as much light for a small size/weight penalty. ;)


Edited by rmollise, 12 August 2014 - 07:48 PM.


#5 Patrick

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Posted 12 August 2014 - 10:12 PM

        Hello,
Someone has been able to compare face to face an SC telescope of 6 "with an 8"?
There is not much difference in terms of: weight, volume, manageability and luminosity-resolution in the images.?
greetings and thanks
Paul

 

I've owned and used both quite a bit.  The C6 is noticably smaller than the C8 in real life.  However, the C8 is still a highly portable scope while the C6 is ultra-portable.  As Rod mentioned the C8 has 1.78x more light gathering power which makes a huge difference on DSO's.  The C6 displays the brighter DSO's very well though.  The C8 is a very popular size for good reason.

 

Patrick



#6 bogg

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Posted 13 August 2014 - 05:42 AM

I agree with Patrick about the C6 vs C8.  I also have both scopes.  For my camper where space is at a premium,  the C6 comes out slightly better as it fits in a nice space that is just too small for the C8 diameter.  Otherwise the C8 has the advantage of the greater light grasp.  For handling I do find that the C6 is slightly easier to handle.  On the SE mount the C6 does not seem to strain the gearing like the C8.



#7 paulsky

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Posted 13 August 2014 - 08:28 AM

Hello,

 As for planetary observation there much difference?
As for deep sky ...?
Thank you  



#8 rmollise

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Posted 13 August 2014 - 09:01 AM

Yes, there is considerable difference, as you'd expect from a 2-inch aperture increase. ;)



#9 Brian Carter

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Posted 13 August 2014 - 09:27 AM

Hello,

 As for planetary observation there much difference?
As for deep sky ...?
Thank you  

 

Yes.

 

 

As a general rule, aperture always wins.  An 8" is nearly double that of a 6" and has a smaller CO.  You will definitely notice a difference for planets, and you'll get about a magnitude deeper for DSOs.  

 

Planets are a good example:  The rule of thumb is that you can't push more than 50x per inch of aperture but in reality the image starts looking pretty dim by then, and you don't actually get any more detail past about 25x per inch, things just get bigger.  What this means for a 6" is that you max out on detail at about 150x, but you'll rarely push this up past 200-250x because the view will start getting dim..  Most nights the seeing in my area will support a lot more magnification than this.  With an 8" 25x per inch will get me to 200x and the views still look good at 300x.  250-300x is usually where seeing starts to get bad.  So you can see there pretty easily how an 8" will give you a lot more than a 6".

 

Personally, I think an 8" is a sweet spot for scopes.  A bigger scope can always show you more, but an 8" will get you to what the sky will reasonably allow unless you live in a really nice area, at least for planets.  For DSOs, bigger is always better, regardless of the sky conditions.


Edited by Brian Carter, 13 August 2014 - 02:59 PM.

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#10 coopman

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Posted 15 August 2014 - 03:17 PM

The 8" brings along with it longer cool down times and a bigger corrector plate surface to collect dew.

#11 jrbarnett

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Posted 15 August 2014 - 10:19 PM

        Hello,
Someone has been able to compare face to face an SC telescope of 6 "with an 8"?
There is not much difference in terms of: weight, volume, manageability and luminosity-resolution in the images.?
greetings and thanks
Paul

Good question, actually.  The reality is the 6" is smaller and lighter by just enough that it works well on the Nexstar 6/8 SE mount.  The 8", though sold on that mount, is not stable.  The 6" is also about half the price of the 8" OTA.

 

If you have the cash and a suitable mount (CG5 class or beefier), the 8" is the better choice.

 

If you have a smaller mount and would like to save $400, the C6 is a good alternative.

 

- Jim



#12 Geo.

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Posted 16 August 2014 - 09:59 AM

The C8 is heavier by a couple of pounds 10 vs 12.5. Or you can find a '82-85 Super C8 with Starbright coatings and have a C8 that weighs less than a C6. I paid $225 for my orange Super C8 and sold the mount for $200. Hard to beat thet price.


Edited by Geo., 16 August 2014 - 10:02 AM.


#13 donnie3

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Posted 26 August 2014 - 11:37 AM

I have both the c6 and c8 orange tube se. bought the 6 first then the 8. I can tell you with out hesitation the 8 will out do the 6 on deep sky any day of the week. its a little heavier but really makes up for that in what you can see. its really the sweet spot in sct scopes. if I ever decide to purchase another sct it will probably be the 9.25, the 11" is tempting but at my age the weight would be the main factor. then again, the meade 10" lx90 only weighs 50 lbs with the fork. it would be a hard choice to make for me.

#14 Jon_Doh

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Posted 26 August 2014 - 11:58 AM

I've owned a C6 and a Meade 8".  The difference going from 6" to 8" inches of aperture was very noticeable.  Things I could only see faintly or with averted vision in the C6 popped out clearly with 8" of aperture.  Collecting two times the light really makes a difference.



#15 Fox1971

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Posted 26 August 2014 - 02:13 PM

I just purchased a "used" C8 OTA from this website in excellent condition for only $350.00. Little reason to buy a C6 based on cost when you can pick up the C8 for the same or less in near new condition.



#16 jrbarnett

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Posted 26 August 2014 - 02:41 PM

I just purchased a "used" C8 OTA from this website in excellent condition for only $350.00. Little reason to buy a C6 based on cost when you can pick up the C8 for the same or less in near new condition.

Except that you can pick up the C6, used, for considerably less than $350.  I know as I just sold one in as new condition for $250 earlier this month.  Comparing used to new is comparing apples to oranges.  The fact is apples:apples (i.e., new:new or used:used), the C6 is considerably cheaper than the C8.  It's easier to mount to.  It has better clearance and a lesser moment arm, aside from the moderate weight difference.  I wouldn't put a C8 on a mount lighter than a CG5.  I would put a C6 on a mount lighter than a CG5.  If you have a CG5 or larger mount already and have the extra dough, it's a no brainer - go with the C8.  If you don't have a CG5 or larger or need to save money, C6 is the better choice.

 

- Jim



#17 Sarkikos

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Posted 26 August 2014 - 03:20 PM

I wouldn't put anything on a CG5 ... on any GEM, for that matter. I've got several of the buggers that I can't wait to sell.  If they were as easy to pack up as eyepieces they'd be gone by now. Of course, there's no shortage of GEM lovers, so it doesn't matter what I say.  I could still sell them.

 

:grin:

Mike



#18 shortbread13

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Posted 26 August 2014 - 05:46 PM

I wouldn't put anything on a CG5 ... on any GEM, for that matter. I've got several of the buggers that I can't wait to sell.  If they were as easy to pack up as eyepieces they'd be gone by now. Of course, there's no shortage of GEM lovers, so it doesn't matter what I say.  I could still sell them.

 

:grin:

Mike

Could you tell me why you no longer like GEMs? I am researching them and wondering if your reasons are what I've found so far as to why people don't like/use them: more complicated and time consuming set up (balancing, polar aligning), more pieces/weight.

 

Thanks!


Edited by shortbread13, 26 August 2014 - 05:47 PM.


#19 Sarkikos

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Posted 27 August 2014 - 02:11 PM

Yes, those reasons sum it up pretty well.

 

Mike



#20 BillP

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Posted 27 August 2014 - 02:47 PM

Yes, those reasons sum it up pretty well.

 

 

Exactly! :lol:



#21 shortbread13

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Posted 29 August 2014 - 09:51 AM

Yes, those reasons sum it up pretty well.

 

Mike

 

Much appreciated! :)



#22 dpippel

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Posted 29 August 2014 - 10:04 AM

It takes me approximately 10 minutes to completely set up my AVX and polar align it well enough for visual use. It breaks down into several easy to manage pieces for convenient transport and I can use multiple OTAs with it. My adjustable observing chair and Baader Clicklock VB make it very convenient to observe with no matter how the mount is positioned.

 

;)



#23 StarWolf57

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Posted 29 August 2014 - 10:35 AM

I tend to agree. I have found that for me, the aversion to GEM's is more psychological than anything else. It probably goes back to the old days with my old Meade reflector that really was a pain to set up. The new mounts are amazingly fast to align and in truth, assembling them only takes a few minutes. Smaller ones can be carried without disassembly (maybe the OTA removed). Everyone's situation is different, so obviously others will disagree, but I think modern GEM's sometimes get a bad rep from their distant cousins.



#24 jrbarnett

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Posted 29 August 2014 - 12:30 PM

It takes me approximately 10 minutes to completely set up my AVX and polar align it well enough for visual use. It breaks down into several easy to manage pieces for convenient transport and I can use multiple OTAs with it. My adjustable observing chair and Baader Clicklock VB make it very convenient to observe with no matter how the mount is positioned.

 

;)

I use both (GEMs and alt-az mounts).  I prefer GEMs for their versatility, load handling capacity and less demanding balance characteristics.  But alt-ax mounts do put the eyepiece in a much more consistent and comfortable range than do GEMs.  You'll move your observing chair around the mount just as often as with a GEM, but will be adjusting your seat height far less often, which makes for a much more relaxing observing session.  The problem is, there are no decent quality, medium load, tracking, GOTO alt-az mounts, which for me relegates the alt-az offerings to second class citizens in the mount world.  Imagine if Losmandy or or even A-P decided to make a high quality, full featured, versatile, visual, GOTO alt-az mount capable of holding up to a C11 or better yet C14.

 

- Jim



#25 Brian Carter

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Posted 29 August 2014 - 12:48 PM

 

It takes me approximately 10 minutes to completely set up my AVX and polar align it well enough for visual use. It breaks down into several easy to manage pieces for convenient transport and I can use multiple OTAs with it. My adjustable observing chair and Baader Clicklock VB make it very convenient to observe with no matter how the mount is positioned.

 

;)

I use both (GEMs and alt-az mounts).  I prefer GEMs for their versatility, load handling capacity and less demanding balance characteristics.  But alt-ax mounts do put the eyepiece in a much more consistent and comfortable range than do GEMs.  You'll move your observing chair around the mount just as often as with a GEM, but will be adjusting your seat height far less often, which makes for a much more relaxing observing session.  The problem is, there are no decent quality, medium load, tracking, GOTO alt-az mounts, which for me relegates the alt-az offerings to second class citizens in the mount world.  Imagine if Losmandy or or even A-P decided to make a high quality, full featured, versatile, visual, GOTO alt-az mount capable of holding up to a C11 or better yet C14.

 

- Jim

 

 

 

You nailed it.  I really like my AVX, it sets up/torn down quickly (less the the 10 minutes someone quoted) and the tracking and goto are great.  But I don't do photography so I don't really need a GEM.  But there's no other alternative really.  An alt-az would be much more intuitive.  I think Losmandy and AP are marketting to photographers... Actually, I think most in the astronomy business are marketing to them, that's where the money is.  Even the AVX is marketed as "Built with astrophotography in mind", which isn't really true.

 

Nice mount though, I don't regret buying it.








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