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Will I see much of a difference between a 10" SCT and 11" SCT?

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#1 Stargazer3236

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Posted 13 September 2019 - 03:34 PM

I am trying to upgrade my next imaging telescope from a Nexstar C8se ota up to either the Meade 10" ACF or Celestron C11. Will I see much of an increase between the two scopes based on light gathering compared to the C8? Does the C11 have that much of an increase over the M10? They are both priced near each other, within $1000, so the outcome will not be huge cash wise.

 

Will I have a better luck with the 11" over the 10" or is it all oranges to oranges?



#2 Bataleon

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Posted 13 September 2019 - 03:53 PM

I am trying to upgrade my next imaging telescope from a Nexstar C8se ota up to either the Meade 10" ACF or Celestron C11. Will I see much of an increase between the two scopes based on light gathering compared to the C8? Does the C11 have that much of an increase over the M10? They are both priced near each other, within $1000, so the outcome will not be huge cash wise.

Will I have a better luck with the 11" over the 10" or is it all oranges to oranges?

From what I understand, ACF coatings are superior to those found in standard Celestron SCTs, so if you're looking for optical quality, the Meade probably has a slight edge, but generally speaking aperture is the name of the game. Will the difference be mind blowing? Nah. But then neither will the difference in coatings. Shop around and find the best deal. If a grand is a reasonable margin for you, you could always look at the Edge 11s too...

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#3 bobito

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Posted 13 September 2019 - 03:56 PM

I went from a C11 to a 12" LX200 and didn't notice much if any difference.  Never did a side by side tho...



#4 M11Mike

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Posted 13 September 2019 - 03:57 PM

If you're going to make a "move up" to gain light grasp - go for the LARGER C11.  It pretty much just makes good sense if the $$$ is the same.

 

M11Mike.  



#5 Alexiecrespo

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Posted 13 September 2019 - 04:16 PM

Hi,

I own a C11 and found first frustrating to learn how to use it. Things like alignment can be frustrating. But I think these goes for any scope if you have no experience.

I did solve all my issues now and is working great. But with a catch, I get a Starsense. Many people argue is not needed or that plate solving is the same, but if you are outside just for a visual session it is the best.

Something you need considere is the flexibility of the scope. CPC have capability to reduce the focal length up to F1.9 with Hyperstar. Also you have other nice features like the motor focuser and wifi along with CWPI for remote control.

Hope this help you.

#6 slepage

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Posted 13 September 2019 - 05:03 PM

You say that you are looking for your "next imaging telescope".  If this is your primary interest then you need to consider only the f ratio for light gathering ability.  The higher the f ratio the slower the scope meaning that you will not gather photons as quickly as a faster scope i.e low f ratio.  As such your f/10 C8 will gather as much photons as a f/10 C11 over the same given time frame.  The difference is that your focal length will be longer so you would be able to go deeper for those small galaxies or planetary nebulas.  So if you care about light gathering for imaging then go faster with a scope that has a lower f ratio.  With that said, look at a handful of the imaging targets that you want to bag.  Look at the size of them and ask yourself what focal length do you need in order to frame the target nicely.  You might be surprised that you will find that a f10 c11 or 10" meade might provide to much power and that you will not be able to frame the whole target on your sensor.

 

I am assuming that you are imaging deep sky,  If you want to do planetary, then you want the most amount of aperture that you can get so that you can get better resolution.  The planets are bright enough so light gathering is not as important.

 

Hope this helps.

 

Steve


Edited by slepage, 13 September 2019 - 05:18 PM.


#7 macdonjh

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Posted 13 September 2019 - 06:05 PM

You say that you are looking for your "next imaging telescope".  If this is your primary interest then you need to consider only the f ratio for light gathering ability.  The higher the f ratio the slower the scope meaning that you will not gather photons as quickly as a faster scope i.e low f ratio.  As such your f/10 C8 will gather as much photons as a f/10 C11 over the same given time frame.  The difference is that your focal length will be longer so you would be able to go deeper for those small galaxies or planetary nebulas.  So if you care about light gathering for imaging then go faster with a scope that has a lower f ratio.  With that said, look at a handful of the imaging targets that you want to bag.  Look at the size of them and ask yourself what focal length do you need in order to frame the target nicely.  You might be surprised that you will find that a f10 c11 or 10" meade might provide to much power and that you will not be able to frame the whole target on your sensor.

 

I am assuming that you are imaging deep sky,  If you want to do planetary, then you want the most amount of aperture that you can get so that you can get better resolution.  The planets are bright enough so light gathering is not as important.

 

Hope this helps.

 

Steve

+1

 

Perhaps post this in the Imaging forum...

 

I think a more apples-to-apples comparison would be between the Meade ACF and a Celestron EDGE 11.  From what I've read (not being an imager myself), the ACF and EDGE optics aren't that much upgrade for planetary imaging (when you use only the center of the FOV), but make a noticeable difference in wide-ish field imaging (since f/10 won't be considered widefield).  

 

Another thing to consider is Meade offers their scopes in native f/8 versions, same light gathering and resolution, faster exposure.  Of course, there are focal reducers for both scopes.

 

My last comment: Meade scopes are generally heavier than Celestron scopes and so might a need stronger mount to be stable enough for long exposure imaging.



#8 carolinaskies

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Posted 13 September 2019 - 07:48 PM

I am trying to upgrade my next imaging telescope from a Nexstar C8se ota up to either the Meade 10" ACF or Celestron C11. Will I see much of an increase between the two scopes based on light gathering compared to the C8? Does the C11 have that much of an increase over the M10? They are both priced near each other, within $1000, so the outcome will not be huge cash wise.

 

Will I have a better luck with the 11" over the 10" or is it all oranges to oranges?

If you're planning on imaging the important factor more than an aperture UPGRADE is a focal ratio DECREASE.    Aperture isn't about 'light gathering' from your imaging perspective but rather resolution... aka smallest detail per pixel.  Remember that focal length is the biggest effect on imaging vs aperture. 

Here's the numbers to crunch...

Currently based on your /ASI294
8se F/10...    F/10, .47pixel, .54x.37 degree field of view, resolution limit .57 arc/sec

$1699  10" ACF F/10 ....  F/10, .38/pixel, .43x.29 degree FOV, res limit .46 arc/sec 
$2299  10" ACF F/8 ....   F/8,  .47/pixel, .54x.37 degree field, res limit .46 arc/sec
$2399  11" Edge F/10 .... F/10, .34/pixel, .39x.27 degree field, res limit .42 arc/sec 
$1779  11" XLT F/10 .... F/10, .34/pixel, .39x.27 degree field, res limit .42 arc/sec 
$1699   8" RASA F/2 .... F/1.97, 2.38/pixel, 2.74x1.87 degree field, res limit .57 arc/sec 
$3499 11" RASA F/2.2 ... F/2.22, 1.54/pixel, 1.77x1.21 degree field, res limit .42 arc/sec. 

The resolution limit range is .15 arc seconds from 8 to 11".  Your seeing is probably going to restrict top theorectical performance.  For imaging the truly faint objects a 10-12" scope just isn't going to make a huge difference from your current 8".  Only by jumping to 14 or 16" will the resolution start making a big difference and when you get to that big you're spending big money for both the OTA and a mount to hold them. 

Where is the difference then in the 8-11?  If you continue to use your ASI294  4/3rds camera the pixel scale is going to be harder on the F/10 apertures of the 10 & 11.  If  you move to the F/8 10" It's the same as your 8se.  Why does this matter?  The robustness of the mount you put your telescope on is where this becomes important. As you move to smaller pixel scales the tracking/guiding must be better and better.  Conversely, as pixel scales increase tracking becomes less an issue.  This is why beginning astroimaging is best with short focal length refractors.   The drawback of them is what? Resolution... aka APERTURE.  So if you can have the best of aperture and focal length strictly from an imaging standpoint it's very good.  This is why the RASA scopes are making a storm in the AP world.  While the field of view is wide, they have increadible resolution in that field.  

Lets take a popular scope for imaging the Orion ED80T... F/6, 1.99/pixel, 2.29x1.56 degree field, res limit 1.45 arc/sec  It is about 25% smaller pixel scale, smaller field of view and almost a full arc second less resolution with your ASI294.   

I would suggest the RASA 8 would be an exceptional upgrade as it will be very forgiving for any mount but provide very nice resolution.  If on the other hand you're still set on more aperture and the longer commesurate exposures to get the smaller field go for the 10" ACF F/8.  It can still be paired with a reasonable focal reducer for dual purpose imaging.   While some suggest the Edge telescopes I don't.  Though you can add Hyperstar, a Hyperstar Edge vs a Hyperstar XLT 11 is pretty much the same as the internal corrector has no effect on the hyperstar system.  
 


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#9 dr.who

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Posted 13 September 2019 - 08:02 PM

For use primarily as a imaging scope the f/8 Meade with its higher quality focuser and mirror locks would be the far better option. To get mirror locks on the Celestron you need an EdgeHD. Or if strictly for imaging could go with a RASA. The downside to the Meade will be its weight and lack of cooling fans that can be operated while imaging. But for fans you need an aftermarket system and a EdgeHD.


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#10 elwaine

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Posted 13 September 2019 - 08:27 PM

Agree with dr.who. For imaging, f/8 is a better choice than f/10. But with the C11, you could shoot a f/1.9... but you image scale would change markedly. 

 

Just want to comment on an earlier post. The focal length doesn’t determine how deep one can go. That’s a function of the aperture. The focal length effects the image scale. 


Edited by elwaine, 13 September 2019 - 08:28 PM.


#11 WadeH237

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Posted 14 September 2019 - 07:58 AM

Assuming that we are talking about deep sky imaging, I would think that the most important consideration would be what it does to your imaging scale and field of view.

 

Going from an 8" F/10 to either a 10" or 11" while staying at F/10 will reduce your field of view significantly.  The same chance will not significantly impact your imaging exposure times, since that's mainly driven by focal ratio.

 

Carolinaskies has a good table of the important numbers.  On his list of scopes, the only scope that really makes sense to me (in terms of light gathering) is the 10" F/8 Meade, and then only by a minor amount.  Beyond light gathering, none of the scope listed are going to have a meaningful increase in resolving power, because they are all going to be seeing limited in practical terms.  The RASA scopes will offer a very significant reduction in exposure times, but they are wide field instruments - and if you want a similar effect, the cheapest option would be to get a Hyperstar lens for your existing C8.

 

Personally, unless you are doing planetary imaging from a site with exceptional seeing, I would not spend the money to move from an 8" SCT to any other SCT.  There just aren't any practical advantages.  If you didn't already have an 8" SCT, I would suggest either the Meade ACF (I would choose an 8" F/10 over a 10" F/8, unless you have a pretty stout mount) or a EdgeHD 8.  But the reason for this has nothing to do with aperture.  It's for other features like a better corrected field, better mirror locks, etc.

 

I'll note that this is not a hypothetical question for me.  A few years ago, I did purchase an SCT exclusively for imaging.  I have a mount that can easily carry any commercially available SCT (it'll actually carry up to a 24" R/C).  Of all the available options, I chose the EdgeHD 8 and added the F/7 focal reducer, and I am very happy with that choice.  I did own a Meade 8" ACF scope in the past, and that was also an excellent imaging scope.  I also have a C14 and have imaged with it.  But for deep sky imaging at a site with less than exception seeing, it just doesn't offer any improvements that make it worth dealing with the size and weight over the 8" (but it makes an exceptional visual instrument or planetary imaging instrument).



#12 Stargazer3236

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Posted 14 September 2019 - 11:28 AM

+1

 

Perhaps post this in the Imaging forum...

 

I think a more apples-to-apples comparison would be between the Meade ACF and a Celestron EDGE 11.  From what I've read (not being an imager myself), the ACF and EDGE optics aren't that much upgrade for planetary imaging (when you use only the center of the FOV), but make a noticeable difference in wide-ish field imaging (since f/10 won't be considered widefield).  

 

Another thing to consider is Meade offers their scopes in native f/8 versions, same light gathering and resolution, faster exposure.  Of course, there are focal reducers for both scopes.

 

My last comment: Meade scopes are generally heavier than Celestron scopes and so might a need stronger mount to be stable enough for long exposure imaging.

Actually, the Meade 10" ACF (26 lbs) is lighter than the Celestron C11 (27.5 lbs). The Celestron C9.25 is 20 lbs, the C14 is 45 lbs and the Meade 12" is 35 lbs, however the Meade 14" is 57 lbs. The Celestron 8" is 12.5 lbs and the Meade 8" ACF is 12.2 lbs. So in some instances, yes, they are heavier towards the larger apertures, but the smaller ones, 8-10 are in fact lighter.



#13 Stargazer3236

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Posted 14 September 2019 - 11:40 AM

OK. Maybe I will go to the Meade 8" ACF instead. However, what about upgrading to a 12" F/5 telescope? Goto Dobsonian? Or a 14" F/5 Goto Dob? My imaging consists of short subs, 15-20 secs and stacking in SharpCap 3.2 Pro. My main interest is being able to image lesser known and obscure planetary nebula along the lines of Ferrero 6, Ferrero 8, the Patchick planetary nebula, Outters 4 and lots of the Minkowski's, Henize, PK's, etc.



#14 dr.who

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Posted 14 September 2019 - 01:27 PM

Agree with dr.who. For imaging, f/8 is a better choice than f/10. But with the C11, you could shoot a f/1.9... but you image scale would change markedly. 

 

Just want to comment on an earlier post. The focal length doesn’t determine how deep one can go. That’s a function of the aperture. The focal length effects the image scale. 

Good point! I forgot about Hyperstar. It means you can image at f/10, f/7, and f/1.9 whereas with the Mead you are likely more limited.



#15 fred1871

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Posted 15 September 2019 - 12:45 AM

OK. Maybe I will go to the Meade 8" ACF instead. However, what about upgrading to a 12" F/5 telescope? Goto Dobsonian? Or a 14" F/5 Goto Dob? My imaging consists of short subs, 15-20 secs and stacking in SharpCap 3.2 Pro. My main interest is being able to image lesser known and obscure planetary nebula along the lines of Ferrero 6, Ferrero 8, the Patchick planetary nebula, Outters 4 and lots of the Minkowski's, Henize, PK's, etc.

If you want to image the small stuff you need decent focal length to get enough image scale, as Planetary nebulae are often small.

 

And you'll need good tracking even with short subs, to maintain resolution/detail. So with a Dob I'd suggest a tracking platform, if that's the way you decide to go. The benefit of an SCT as you know is long focal length in a short tube which helps image scale without the scope getting too long. 

 

The Meade scopes at f/8 rather than f/10 will give you more light in less time, but at the expense of some image scale. For smaller objects I'd suggest better scale is the way to go. So that puts you back with f/10 scopes, whether Celestron or Meade. Standard SCT (Celestron) or coma-free (Meade) or coma-free and flatter field (Celestron Edge). Your choice on that.

 

The guys I know who do high quality deep-sky imaging including smaller objects use bigger apertures - better scale at the same f-number - and solid equatorial mounts.



#16 Stargazer3236

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Posted 15 September 2019 - 11:38 AM

Good point! I forgot about Hyperstar. It means you can image at f/10, f/7, and f/1.9 whereas with the Mead you are likely more limited.

Actually, the Edge reducer costs 10X that of the Meade F/6.3 Reducer Corrector. So, in essence, the Edge will cost you more in the long run with accessories than the ACF. The ACF can still use the Meade reducer Corrector. Because the Edge puts it's corrective lens in the baffle tube, you cannot use a normal reducer with the Edge.



#17 Astrojedi

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Posted 15 September 2019 - 07:44 PM

Actually, the Meade 10" ACF (26 lbs) is lighter than the Celestron C11 (27.5 lbs). The Celestron C9.25 is 20 lbs, the C14 is 45 lbs and the Meade 12" is 35 lbs, however the Meade 14" is 57 lbs. The Celestron 8" is 12.5 lbs and the Meade 8" ACF is 12.2 lbs. So in some instances, yes, they are heavier towards the larger apertures, but the smaller ones, 8-10 are in fact lighter.

Couple of corrections the C9.25 is 18.5lb w/o accessories. The Meade 8” more like is 15.5lb w/o accessories.



#18 dr.who

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Posted 15 September 2019 - 08:16 PM

Actually, the Edge reducer costs 10X that of the Meade F/6.3 Reducer Corrector. So, in essence, the Edge will cost you more in the long run with accessories than the ACF. The ACF can still use the Meade reducer Corrector. Because the Edge puts it's corrective lens in the baffle tube, you cannot use a normal reducer with the Edge.

I realize this. But I wasn’t aware that price of accessories was a factor. In light of that data point then, yes, the Meade is the more cost effective option.



#19 fred1871

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Posted 15 September 2019 - 09:30 PM

Repeating the point made by the OP - if he's wanting to image SMALL objects such as obscure Planetary nebulae (#13 above), he will not want a reducer because it kills the image scale, so what is imaged becomes less detailed.

 

Of course, if recording the small objects as less detailed but detected, then a faster focal ratio is helpful - fewer subs to collect.

 

Meade 10-inch with 0.63 reducer is 1575mm focal length. At f/10, 2500mm. Celestron Edge 11-inch at f/7 is 1960mm focal length, at f/10 it's 2800mm. Choose your image scale.




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