In brief, there is a 16” Sky-Watcher Go-To Dobsonian (Sky-Watcher Flextube 400P SynScan 16”) + extras available in my local area for a very good price. However I currently own an older model Meade LX50 10” SCT (non-Go-To, but motorized) on a fork mount + wedge. I am VERY interested to understand the differences I might see between the 10” and the 16”, but I am struggling finding good resources online that clearly show what the visual differences might be.
Is the upgrade from 10” to 16” going to produce dramatically superior views, or only “kinda” better views compared to my 10”?
(I am toying with the idea of asking the seller if he might show me the scope under clear, dark skies, but the weather lately has been back and forth, and I feel as though if I go to see the scope a second time, I am almost committing to buying it. So I’d rather get some ducks in a row first, if I can)
Here is the “TLDR” version (and to give you a sense of the research I have done to this point):
Just a disclaimer:
I don’t care about size, weight, bulkiness, light pollution etc etc. I have considered these aspects plenty already, and I am fine with it. Where I live gets very dark, and I am perfectly fit enough to haul this scope around my yard (I have already seen it in person, and am comfortable with this). So no need to dive into the “practical differences” of owning a huge scope. Realistically, my 10” is a beast to setup anyway. So I am no further behind in this regard.
I am just curious if anyone has any direct experience, or resources available that might help me determine the visual difference between a 10” aperture and this potential 16”? Specifically on DSOs.
With this scope being local and available for a VERY good price ($3000 CAD, and its in like-new condition + electronic dew heater, Celestron battery bank, laser collimator, some eyepieces, shroud etc), I am extremely interested. Especially considering this may be my only chance to own such a large telescope, as I may not be able to justify the costs of purchasing new in the future.
However, $3K is still a lot of money, for a hobby I have only started to get into. So I am still wondering what this scope might offer me above my current 10”.
I really like the idea of a Go-TO scope, as I struggle with star hopping in the ultra-magnified 2500mm FL 10” SCT. So “Go-To” is actually a huge draw for me. That being said, I am also considering de-forking my Meade and putting it on a CGEM that can handle it as payload (this would be much cheaper).
I’ve been reading and searching for resources online to help me. There are only so many “Telescope Simulators” out there, and most only simulate FOV, not object detail and brightness. However, this site attempts to do everything:
I’ve gone through a bunch of simulations at the above link (10” vs 16”, same Mag level) to get a sense of visual differences. And honestly, this makes it look like there is hardly ANY difference between the 10” and the 16”.
This can’t be true though, right? Logically speaking, the 16” is SO much larger than a 10”, the visual must be orders of magnitude more impressive?
So, I started researching some of the maths to calculate some of the fundamentals. But I struggle with many of the terminologies.
E.g. aperture area (classic areas of a circle, pi * r squared):
10” = 78.54”(sq)
16”= 201.06” (sq)
Which equates to: 201.06/78.54= 2.56 times larger light collecting area! This sounds great! More than doubling your light gathering capabilities without actually doubling the aperture diameter.
So 2.56x the light gathering ability must make the 16” eons better than the 10”, right?
…But still, the Telescope simulator doesn’t look all that different “in real life”. So there must be more to this story.
So then I started looking into “Magnitudes” and “Dawes/Rayleighs” limits etc etc.
This is also where I start to get a little lost in terminology.
However, from what I can find, these factors really don’t appear to be all that different (ah ha! Perhaps this is why the Telescope simulator shows very modest differences?):
Meade 10” LX50 (from what I can dig up):
Dawes Limit (called “resolving power” on the spec sheet I found, and measured in arc seconds)= 0.45
Limiting Visual Magnitude (approx.)= 14.5
Rayleigh limit= ???
Sky-Watcher 16” (Synscan 400P) Dob:
Dawes Limit= 0.29
Limiting Mag.= 15.5
Rayleigh Limit= 0.34
Again, I am unfamiliar with these terms, and only understand them as well as Wikipedia could explain them to me (i.e. I only kinda know what they mean).
But from those specs, it appears these two scopes are not “vastly” different in terms of visual experience.
Dawes Limits show resolving powers that appear to be in the same general ballpark. Unless a difference of 0.16 arc seconds is huge?
And the limiting magnitude between the two is only a spread of 1.
Which means what, exactly? I can supposedly now see objects with a visual brightness magnitude of 15.5 instead of 14.5? (I know I know, this is some kind of a Log scale, so a difference of “1” is fairly major, but still. Going from 14.5 to 15.5 doesn’t seems crazy extreme for how much larger the 16” is).
Is this Mag. Diff of 1 actually something to write home about? I just don’t have the experience to know.
So I am now lost in a sea of possibly contradicting information. And I am hoping some folks on here might be able to put this all into perspective for me.
On the one hand, we have a scope that is MUCH larger, a little more than double the light collecting capability, and lots of support from fellow astronomers who support that larger 16” dobs are amazing.
On the other hand, I see specification limits which don’t seem all that impressively different, and a Telescope simulator which supports this idea.
So I am lost! Haha.
Do I upgrade my 10” SCT to a CGEM, or do I purchase the 16” Dob Go-To?
Any words of wisdom would be greatly appreciated.
Also thank you anyone who has stuck it out with me to this point in the post! It is very appreciated any help you can provide.