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Celestron C 11XLT for visual use in urban area? Is this just aperture fever?

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#1 Mwestcott

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Posted 28 January 2022 - 05:22 PM

Folks,
I am very lucky to have  2 wonderful scopes -  a Takahashi FS128, and Mewlon 210.
I dont have them mounted permanently,  mount one or other on an ioptron IEQ45.
I live in central London - generally poor skies and moderate light pollution. We do get occasional clear nights with mild temperatures and little temperature fluctuation.
I am purely visual and have no real desire for imaging. I have this idle thought that maybe a Celestron 11 inch (xLS) would be good for some visual targets. For visual ,  aperture always wins. Would it allow me to see deeper and combat pollution?
I have little space and don’t really fancy a Dobsonian. I have always liked the equatorial mount driven views.
Is the idea of getting a C-11 crazy? I am happy with what I have and It should not take much to persuade me out of this. But I just can’t help it. 
The cool down time of a C-11 is notoriously slow and I don’t have a permanent set-up. The aperture is likely to be above critical limit for good seeing most of the time (air columns) and our seeing is not good. The C11 is heavy, but only slightly more than the  Mewlon 210.
I am fussy about the view and appreciate the pin-point stars that my current scopes deliver - I am spoilt really. In contrast, many  folks complain of “woolly” stars in basic SCT.
I can’t afford a C-11 Edge so it would be a XLT. I am not imaging anyway 
It seems I can buy a used  C11 XLT pretty cheaply but perhaps there is a reason for that and how do I avoid getting a dud?
The alternate would be a Mewlon 250 but the coma corrected CRS is a pricey scope and the old style Mewlons are rare. Also, I doubt if the jump from Mewlon 810 (which I currently have) to 250 would be that significant.
But perhaps a jump from 8 inch (210) to 11 would be? By my calculation it lets in 1.9x more light 
Is this just aperture fever?
Help me make a sensible decision. 
Clear skies 


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#2 bobhen

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Posted 28 January 2022 - 06:06 PM

In the past, I’ve owned a Mewlon 210 and a C11 and I also observe from heavily light polluted (Bortle 8-9) location.

 

Between a C11 and a Mewlon 210 and observing deep sky objects in light pollution, some objects might look better in the C11 and some in the Mewlon 210. Objects like globulars that do not need much contrast might look better in he C11 but objects that need contrast like some nebulas, etc. might look less washed out in the Mewlon 210.

 

In any case, I doubt that the jump would deliver a huge improvement or show you things that you cannot already see fairly well in the Mewlon 210.

 

The stars will generally look sharper in the Mewlon.

 

They only way to defeat real heavy light pollution is to do EAA short exposure imaging or get an image intensifier or drive to a dark sky. That’s why I did EAA for 15-years and now observer the deep sky using an image intensifier.

 

Bob


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#3 davidmcgo

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Posted 28 January 2022 - 09:40 PM

Won’t help with faint emission nebula or galaxies but for globulars and planetary nebula, a C11 pulls in a lot more detail than an 8”.  Definitely a big step up even in suburban light pollution.

 

Dave


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#4 scoale

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Posted 28 January 2022 - 10:31 PM

I own a C11.  First, know that you are not going to get pinpoint stars unless a) you have a solid example b) it is well collimated c) it is thermally stable and d) you have decent seeing. 

 

As far as examples go, mine is not exceptional but, again, I'm primarily using for DSO in my 18.5 backyard.

 

Donut collimation is easy enough but fine collimation on an in-focus star can be challenging without great seeing.  Not too big of an issue if you are primarily using the scope for DSO (my use case), but definitely matters for solar system viewing (but you have solar covered with your TAKs)

 

I use reflectix and/or my lymax to deal with thermals.

 

As far as reach goes, my experience matches Dave's assessment that you are not going to see a significant change on galaxies, and only a moderate bump on nebula.

 

I bought the C11 for exactly the reason you are contemplating but have learned that Bob is exactly right: if you really want a step change in a light polluted environment look into an intensifier and/or EAA.  In fact, now that I have an intensifier, I may switch from a C11 to a 9.25 at some point.

 

Very, very best of luck with your choice

Stephen



#5 Cfeastside

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Posted 29 January 2022 - 09:35 AM

I agree with all the above.  I think for globs and open clusters it will help but not for faint fuzzies unfortunately.  Do you have access to dark skies like bortle 3 or better?  At least occasionally?   I bought my c11 in the fall specifically to take to my dark sky, bortle 1, location during late spring through the fall.  I have a c9.25 and was blown away by what i saw looking at some of the galaxies with it.   I had always wanted one so i bought it.  I live under b4 skies and the c11 and c9.25 are pretty unimpressive with the same galaxies.  Cool down times are definitely an issue.  Especially at my backyard where temp inversions are pretty severe; live in a deep valley.   My dark sky site though is in the mountains so temp inversions arent as severe.  Havent got it up there yet but i cant wait til the snow melts off!



#6 rmollise

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Posted 29 January 2022 - 10:09 AM

Folks,
I am very lucky to have  2 wonderful scopes -  a Takahashi FS128, and Mewlon 210.
I dont have them mounted permanently,  mount one or other on an ioptron IEQ45.
I live in central London - generally poor skies and moderate light pollution. We do get occasional clear nights with mild temperatures and little temperature fluctuation.
I am purely visual and have no real desire for imaging. I have this idle thought that maybe a Celestron 11 inch (xLS) would be good for some visual targets. For visual ,  aperture always wins. Would it allow me to see deeper and combat pollution?
I have little space and don’t really fancy a Dobsonian. I have always liked the equatorial mount driven views.
Is the idea of getting a C-11 crazy? I am happy with what I have and It should not take much to persuade me out of this. But I just can’t help it. 
The cool down time of a C-11 is notoriously slow and I don’t have a permanent set-up. The aperture is likely to be above critical limit for good seeing most of the time (air columns) and our seeing is not good. The C11 is heavy, but only slightly more than the  Mewlon 210.
I am fussy about the view and appreciate the pin-point stars that my current scopes deliver - I am spoilt really. In contrast, many  folks complain of “woolly” stars in basic SCT.
I can’t afford a C-11 Edge so it would be a XLT. I am not imaging anyway 
It seems I can buy a used  C11 XLT pretty cheaply but perhaps there is a reason for that and how do I avoid getting a dud?
The alternate would be a Mewlon 250 but the coma corrected CRS is a pricey scope and the old style Mewlons are rare. Also, I doubt if the jump from Mewlon 810 (which I currently have) to 250 would be that significant.
But perhaps a jump from 8 inch (210) to 11 would be? By my calculation it lets in 1.9x more light 
Is this just aperture fever?
Help me make a sensible decision. 
Clear skies 

 

The answer? Yes, aperture makes a difference in city and in the suburbs. When I moved out to the suburbs where we are now, I did some experimenting. I found that while an 8-inch (SCT or Newtonian) was OK, my C11 made a striking difference under my skies (mag 5 at zenith on a really good night). The 11 made the brighter objects into showpieces, while in the 8, even the "good" Messiers and NGCs were lackluster.

 

UNFORTUNATELY...  Because of an accident and other health issues, shortly thereafter I found I just simply couldn't and didn't want to handle a fork-mount C11 anymore. I tried putting it on a GEM, and that helped, but I had a hard time setting up a German mount sufficient for the OTA. What else I found out? A 10-inch Newtonian did every bit as well as the C11, and I was able to go to an inexpensive and light GSO Dobsonian that provided that needed performance increase over the 8-inch scopes.

 

smile.gif


Edited by rmollise, 29 January 2022 - 10:11 AM.

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#7 rmollise

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Posted 29 January 2022 - 10:13 AM

Won’t help with faint emission nebula or galaxies but for globulars and planetary nebula, a C11 pulls in a lot more detail than an 8”.  Definitely a big step up even in suburban light pollution.

 

 

 

I found going from 8 to 10-inches helped substantially on everything. I might still need a filter for dim nebulae, but they looked better filtered in the 10-inch than filtered in the 8. Galaxies were even more improved with more aperture. Details could still be sketchy, but I could certainly see many MORE galaxies with the 10. smile.gif


Edited by rmollise, 29 January 2022 - 10:14 AM.

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#8 junomike

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Posted 29 January 2022 - 10:51 AM

If only two I'd go with the 128 and C11.  One for fast G 'n G + a wider field and the other for better seeing and smaller DSO's.



#9 carolinaskies

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Posted 29 January 2022 - 04:57 PM

Folks,
I am very lucky to have  2 wonderful scopes -  a Takahashi FS128, and Mewlon 210.
I dont have them mounted permanently,  mount one or other on an ioptron IEQ45.
I live in central London - generally poor skies and moderate light pollution. We do get occasional clear nights with mild temperatures and little temperature fluctuation.
I am purely visual and have no real desire for imaging. I have this idle thought that maybe a Celestron 11 inch (xLS) would be good for some visual targets. For visual ,  aperture always wins. Would it allow me to see deeper and combat pollution?
I have little space and don’t really fancy a Dobsonian. I have always liked the equatorial mount driven views.
Is the idea of getting a C-11 crazy? I am happy with what I have and It should not take much to persuade me out of this. But I just can’t help it. 
The cool down time of a C-11 is notoriously slow and I don’t have a permanent set-up. The aperture is likely to be above critical limit for good seeing most of the time (air columns) and our seeing is not good. The C11 is heavy, but only slightly more than the  Mewlon 210.
I am fussy about the view and appreciate the pin-point stars that my current scopes deliver - I am spoilt really. In contrast, many  folks complain of “woolly” stars in basic SCT.
I can’t afford a C-11 Edge so it would be a XLT. I am not imaging anyway 
It seems I can buy a used  C11 XLT pretty cheaply but perhaps there is a reason for that and how do I avoid getting a dud?
The alternate would be a Mewlon 250 but the coma corrected CRS is a pricey scope and the old style Mewlons are rare. Also, I doubt if the jump from Mewlon 810 (which I currently have) to 250 would be that significant.
But perhaps a jump from 8 inch (210) to 11 would be? By my calculation it lets in 1.9x more light 
Is this just aperture fever?
Help me make a sensible decision. 
Clear skies 

Aperture and focal ratio are two advantages of the C11 vs the 210.  And others are right in that EAA will extend the usefulness of any telescope you choose to stick with in those challenging skies.  The Mewlon is a terrific telescope, there is no denying it... but it will easily fund a more useful combination in your situation.  

A reasonable C11 on the worst day will be as good as the 210 in London, but on the better days it will definitely outperform the Mewlon in resolving fainter detail. The figure of the Mewlon will make it's field very nice... but if you're aiming for more detail and more light the best figure isn't going to overpower that much more light grasp.  Pop on a reducer and binoviewer and you'll be pleasantly happy using both eyes.  And when you are observing the planets the extra resolved detail really is where the C11 is going to improve your experience.  



 


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#10 Mwestcott

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Posted 30 January 2022 - 03:32 AM

Thanks everyone for your helpful replies. 

Plenty  to think about. 
Unfortunately  I am stuck with the skies I have - impractical to drive to a dark dark location.

It seems to me that the C11 might lead to only to a modest improvement. there again the Mewlon is a very nice scope. Practical, and  cools down fast. I am reluctant to part with it as they are hard to come by, as opposed  to C11s. I am very pleased with the contrast and detail, especially on planets and bright globulars.   I like the idea of exploring binoviewers.

I shall look at image intensifiers, but that sees, quite an expensive set up (was looking at the televue).

Any advice welcome.
clear skies  



#11 Reid W

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Posted 30 January 2022 - 08:14 AM

When my u210 arrived, I thought I had a good C11.... and it was a good optic.  With binoviewers, the C11 delivered very, very good planetary views.

 

In direct comparisons on open clusters- like Double Cluster,  the C11 showed more, but what the u210 could show was better.  The improved contrast of the Mewlon made planetary nebula "pop" in low power views.

 

Mounting.  Huge difference in ease of setup.  I have a driveway and would wheel out the Atlas/C11.  With the Mewlon, carry out AZ-Pro, set Mewlon.  If I had to set the 11 every time-well that would have been a drag.


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#12 CHASLX200

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Posted 30 January 2022 - 08:38 AM

The answer? Yes, aperture makes a difference in city and in the suburbs. When I moved out to the suburbs where we are now, I did some experimenting. I found that while an 8-inch (SCT or Newtonian) was OK, my C11 made a striking difference under my skies (mag 5 at zenith on a really good night). The 11 made the brighter objects into showpieces, while in the 8, even the "good" Messiers and NGCs were lackluster.

 

UNFORTUNATELY...  Because of an accident and other health issues, shortly thereafter I found I just simply couldn't and didn't want to handle a fork-mount C11 anymore. I tried putting it on a GEM, and that helped, but I had a hard time setting up a German mount sufficient for the OTA. What else I found out? A 10-inch Newtonian did every bit as well as the C11, and I was able to go to an inexpensive and light GSO Dobsonian that provided that needed performance increase over the 8-inch scopes.

 

smile.gif

I could have bought a 11" GPS for $1500 this weekend when i bought my C8. Thing looks just as big and heavy as my two 12" LX200's were. Just not something i wanna deal with anymore.



#13 dnrmilspec

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Posted 30 January 2022 - 08:51 AM

I have not used a Mewlon but when I went from an 8" SCT to the 11 I noticed a significant difference in what I like the most....Gobulars and Galaxies.  Is there a club nearby that could facilitate your looking through one?



#14 Jeffmar

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Posted 02 February 2022 - 11:58 AM

Having 3 inch, 5 inch, 8 inch, 11 inch, and 14 inch telescopes, I can tell you that bigger is always better in light polluted areas. Given good collimation larger scopes are always better, when you aren’t in a dark area.  




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