16" dob vs 11" SCT

[msacco]

Hi! This is sort of a hypothetical discussion, but thinking about the future I believe I'd want to upgrade my equipment eventually(currently have a 8" Skywatcher with EQ5 goto, and totally satisfied with it).

So I've been looking around a little bit, and I believe the max budget I'd go with would be around 4000-4500$.

For that price range the best thing I could see is 16" dob goto or a 11" SCT goto(I'm not from the US, so maybe the prices would be different to you). The main purpose of the telescope would be for visual observing I believe, but my brother recently bought a DSLR and we gave it a shot on the 8" and EQ5(which should be pretty bad), and it was kinda cool, so might thinking of having that as an option as well.

What I'm not sure of is if it's even possible to image with a dobsonian? It would make sense that a heavy camera would destroy the balance?

How difference is the 16" dob from the 11" SCT? Will I be able to see incredibly more with the 16" compared to the 11" SCT?

One more consideration is that the current setup is really heavy and messy to carry, not all that hard, but not that easy, Obviously a 16" dob would be much more complicated, and I'm not even sure it can be moved by 1 person, as for the 11" SCT, I'm not really sure, it's a bigger aperture, but much smaller generally, so it would make sense that it will be easier to carry around.

I believe that when the time comes, I would probably just search for a second hand dob/SCT and just go with it(it's not easy to find a second hand one where I live).

Would love to hear your thoughts  

Edited July 11, 2019 by msacco

[msacco]

Anyone? 🙂

I was expecting some cool and interesting discussions here 

[TareqPhoto]

No answer because there will be no one adequate answer, if you want replies they will give you too many answers.

First, have to know that aperture is aperture no matter what people will tell you about the scope design itself or type, so 16" is definitely larger than 11", and you can manage some factors and other factors like seeing isn't in your hand, but between 16" and 11" i will blindly choose 16" and don't listen to those who will tell you that 11" SCT is very portable and capable, yes, but i want 16" aperture not 11", this is my simple answer.

You can shoot with 16" Dob, i saw that on the net only, i myself decided to go with 20" customized design and later i will add mount or platform, you can use this 16" for visual perfectly, and it is Goto then it can be enough for a while, and if you plan to do planetary imaging then it is also an amazing scope, maybe goto isn't too much for planetary, but you can manage it somehow, and i advise you if you buy one of those then just buy ZWO planetary camera, 11" SCT or 16" Dob are amazing for planets and the moon.

[RT65CB-SWL]

For lunar and planetary, I personally would go for the SCT. Also, being a shorter tube, the eyepiece will be located at a comfortable position. One of the downsides to any SCT is that they are they notorious dew magnets.

I own a C6/SCT, and it is comfortable for one person assembly/dis-assembly, though an 11" SCT maybe more of a challange.

 

The other parts you will need to consider is the mount and tripod/pier. What is the maximum payload/weight limit? 

My Vixen GP is at the maximum payload with both my C6 and 're-modded' ETX105, (see image above).

 

Also, are you going to be using 1.25" or 2" eyepieces?

<---These two eyepieces are quiet heavy, so I use 1.25" when dual-mounted on the Vixen GP...

...unless I mount them on my Tele-Optic Giro --->

Edited July 13, 2019 by Philip R

[vlaiv]

I would choose 16" dob.

Both have advantages and disadvantages, and it's more - what I can live with rather than which one is better.

Of course, my choice is biased by both my previous experience and my interests.

I suspect that portability will give you same sort of headache in both, but of a different kind.

11" SCT will require quite heavy EQ mount to be stable - at least something in EQ6 class. This means around 35kg of gear for that (mount head, counter weights and tripod + any sort of battery for field work is extra). Scope is around 12Kg, so that is totaling at about almost 50Kg.

16" dob is probably going to weigh about the same if manual (although there are light weight versions that total at about 40Kg, but these don't have goto for example), but some examples will weigh as much as 90Kg total! (like SW 16" goto dob).

Setup time will probably be in favor of dob. "Compactness" (if one can use that word with such large scopes) will be a plus with SCT (tripod legs fold, mount head detaches, scope is shorter - but this adds to setup time as you need to assemble more parts in the field).

If you don't need goto - maybe better option (lighter) would be to go for regular dob and EQ platform. This will give you about hour of tracking (before "rewinding"), will cost less and probably be less bulky, but you won't have automatic finding of objects (if that is something that is important to you).

Other quirks include - Dew on SCT, slower cool down for larger optics (this is a minus for dob, but can be handled with fans in both, and also there are dew heaters) - some don't like observing position with dob. I'm used to it, but my dob is 8" and therefore quite small - I do my observing seated down. 16" is going to be quite high, and you'll need to stand up most of the time and even use step ladder, depending on your height.

Optically, 16" will have an edge, for both planets and DSO work. Edge on planetary performance, you probably won't notice 99% of time. You need very steady skies to reach difference with apertures of that size. DSO difference will be noticeable, no question about that.

Some of above might not be "applicable" to your case, since you live in Israel, right? (reading from your account data). I guess humidity might not be an issue most of the time (unless you are close to sea) and desert climate tends to provide steady atmosphere (but also rapidly changing temperature) - so one is a plus for larger aperture, while other is a minus - rapidly changing temperature prevents telescope to be thermally stable.

For planetary imaging I would also choose 16" aperture, and dedicated planetary camera (rather than DSLR).

If DSO imaging is of any interest, then that pushes your decision in SCT direction - not because of the scope, but rather because of the mount. You can reuse same mount for AP - and get yourself manageable scope for AP (don't try to do it with SCT - you will run into host of problems and that is not something that you want to do if you don't have experience in AP and want to use SCT for imaging for any particular reason).

Last thing - budget, 16" dob with EQ platform will probably cost at least 50% less than SCT and EQ mount, but that will largely depend on model (dob model in first case, and mount model in second case, and of course SCT model - Celestron regular, or EdgeHD, or maybe Meade one ...).

This is for "base / bare bone" system. Accessories will probably cost more for dob. I know, that sounds strange, but 16" dob is fast scope, and you need to account for that so if you want very good view with it, that means - coma corrector for visual and higher end eyepieces that can handle the speed of the scope. With 11" SCT you don't have that issue - at F/10 most EPs will work fine.

Hopefully this will help your decision.

[Paul73]

I have a manual 16” Dob. Aperture is king.....

However, Unless you can wheel it out in one piece, I’d be worried about the practicalities of living with a big heavy scope. I didn’t use mine much until i’d built a trolley to get it to my observing spot.

Paul

[TareqPhoto]

6 hours ago, Paul73 said:

I have a manual 16” Dob. Aperture is king.....

However, Unless you can wheel it out in one piece, I’d be worried about the practicalities of living with a big heavy scope. I didn’t use mine much until i’d built a trolley to get it to my observing spot.

Paul

Hopefully i can find [if can't build] a stable sturdy effective safe trolley to be used with my upcoming dob with is 20".

[Waldemar]

To give you something to think about: the 16"dob gathers 211% more light then the 11"SCT. ((16:11)²)
On top of that the focal-ratio of the dob is a lot bigger (F5) then the SCT (F10), so 4 x more light per mm² with the same aperture.
We are talking about huge differences now, so they are totally different beasts. While tthe SCT is perfect for moon and planets and small galaxies, the Dob is perfect for wider field and fainter object observations.
Both are hard to image with though. The SCT because of the long focal length and the dob because of it's construction.
So if imaging will be your objective, then neither of these will be easy to handle, but not impossible.

I hope this helps a bit with making a decission.

Edited July 13, 2019 by Waldemar

[Astro-Geek]

(Pun alert)

The delay in answers to the opening question may indeed be because it was so Nebulous...  😀

Modern manufacturing processes have made pro quality kit so much more affordable these days, so the choice is much greater.

My budget is much more modest (understatement of the year), and I faced the same dilemma, (Mak/SCT versus Big Dob), so I bought both, secondhand......

Admittedly on a somewhat smaller scale, but with a similar size differential,  a 12" Goto Dob, and a 180 Skymax Mak.

I now have the advantage of hindsight, and I can safely say that I like both equally.  The 12" (flextube) Dob is just about portable and is, as they say, a real "light bucket" for distant objects. The 180 Mak is amazing with Planets and the Moon, with the 2700mm focal length enabling high magnifications without having to resort to Barlows or very short focal length eyepieces.

You also mentioned that your current setup of the 8 inch Newtonian on an EQ5 is heavy and messy to carry, but the 16 inch Dob will be much heavier and bulkier, albeit on a wheeled platform.  Likewise, an 11 inch SCT will require a bigger EQ mount, like an EQ6, which is a much heavier, hernia inducing beast compared to the 5. 😧

The big Dob will be superb for visual, but when your budget reaches this scale of aperture, an Equatorial mount is the most logical way to go for Astro Photography.

 

[barkis]

Between the two scopes you have mentioned, my choice would be 
the 16" Dobsonian. The light gather of the Dob. wins out for me.
If your SCT was on a permanent pier in an Observatory, then the choice would 
be a more  difficult one, but the SCT would probably win out from a convenience point of view.
Ron.

 

[MarsG76]

17 hours ago, vlaiv said:

don't try to do it with SCT - you will run into host of problems and that is not something that you want to do if you don't have experience in AP and want to use SCT for imaging for any particular reason

I agree with everything you said except the quote.. why not? I don't think that it so hard.

 

[glynnlondon]

The DOB has the superior aperture so for visual that would win out for me.

You could of course also get a small frac like an ed 80 , they are fairly ubiquitous in the UK secondary market and go for a couple of hundred pounds.

That could work for ap on your eq5 and use the DOB for visual maybe.

[Paul73]

I agree. Trying to get one scope to do all things will lead to big compromises. I have a 16” Dob and a little ED72 on a driven EQ5 with a DSLR for dabbling in imaging or wide field visual.

Paul

[vlaiv]

1 hour ago, MarsG76 said:

I agree with everything you said except the quote.. why not? I don't think that it so hard.

 

You don't think it is hard for someone starting with AP to image with scope that has 2800mm focal length and shifting mirror (that you need to guide with OAG)?

Ok, agreed - not hard to image at all, same "level" as with anything else, you assemble the thing and start exposures. Getting decent image out of it will probably be somewhat harder than for example 3-4" apo or similar

 

[msacco]

Thanks everyone! I was not expecting an answer, as obviously there is no answer for that, this is why it's more of a discussion than an answer.

All of your answers simply made it much harder for me to choose, but a few things I'd like to add up as it seems like it wasn't clear enough.

The budget I mentioned above is the complete budget for the "whole package", what I mean by that, is that this is the SCT with the mount included:

https://www.celestron.com/products/cpc-1100-gps-xlt-computerized-telescope

And this is the 16" dob:

http://skywatcher.com/product/bk-dob-16-synscan/

So one important thing is that the SCT is an ALT-AZ mount, which should be not as good as an EQ mount for AP as far as I understand, which might go further in favor of the dob.

I wonder if I should go lower in aperture maybe, and then have a telescope for visual, and another for AP, like a small refractor or something similar that will go with my EQ5, just as some here suggested.

The issue is that the prices where I live are so damn high

The SCT 11" is sold from celestron for 2700$, and I need to buy it for 4500$ ^^

That's still far in the future, and I probably won't buy anything anytime soon, mostly because I need a lot of time to think what I actually want.

[Paul73]

You could always ditch the GoTo from the Dob. That saves money and a chunk of weight. The Skywatcher 16” is a heavy old beast without adding motors.

Paul

[MarsG76]

39 minutes ago, vlaiv said:

You don't think it is hard for someone starting with AP to image with scope that has 2800mm focal length and shifting mirror (that you need to guide with OAG)?

Ok, agreed - not hard to image at all, same "level" as with anything else, you assemble the thing and start exposures. Getting decent image out of it will probably be somewhat harder than for example 3-4" apo or similar

 

Sure a 3 or 4" scope would be easier but those are not one of the choices here.... Everyone statrs somewhere, I started with a SCT and eventually worked through the obstacles... Overall I dare say that imaging with a C11, with or without a FR, would be easier than with a 16" Dobsonian.....

[Mr niall]

This was touched on in a thread a couple of years ago may be of some help:

 

 

[jetstream]

On 11/07/2019 at 10:28, msacco said:

How difference is the 16" dob from the 11" SCT? Will I be able to see incredibly more with the 16" compared to the 11" SCT?

I have a very good 10" dob and an excellent 15" truss dob. I observe under above average seeing quite a lot, both scopes are f4.8.

The visual difference on the moon and planets is substantial Tareq with much more fine detail showing in the 15", much more.

You might want to consider the f ratio, fully illuminated field into consideration for imaging in particular.

[vlaiv]

3 hours ago, MarsG76 said:

Sure a 3 or 4" scope would be easier but those are not one of the choices here.... Everyone statrs somewhere, I started with a SCT and eventually worked through the obstacles... Overall I dare say that imaging with a C11, with or without a FR, would be easier than with a 16" Dobsonian.....

Of course, you are right about that, but I did not recommend using 16" dob for DSO imaging - my suggestion was - if DSO imaging is an option, SCT + EQ mount is more sensible choice because one can later add small imaging scope to be used with EQ mount in that role. SCT would remain visual and planetary AP scope in that case.

[GavStar]

I have both a c11 and a 16 inch goto dob. I note that several people have said go for the 16 inch dob, particularly for visual, due to the extra aperture, and I understand why.

But I think it’s also worth restating the obvious ‘the best telescope is the one that you actually use’ comment. I think this should be emphasised since a 16 inch dob is not easy to transport around imo. Ideally you would store it fully setup and then just wheel it out on wheelbarrow wheels. 

I use my c11 on a lovely panther TTS alt az mount and I find it very easy to transport and setup. In particular, the c11 ota is not that big or heavy and the mount packs away into conveniently sized packages. 

However, my 16 inch dob is a bit of a beast even though it’s a ‘compact’ version. With the mirror in place, the mirror box weighs around 30kg which is quite heavy to move around carefully - I now tend to move the mirror box without the mirror in it. And the footprint of the dob is pretty large - it’s not straightforward to pack into my Discovery Sport (and the back seats have to go down).

For my preferences, the c11 is much easier to setup and observe with (I also like the seated observing position of the c11 compared with standing for the 16 inch dob).

As a result, my c11 gets used many more times than my 16 inch dob and for this reason I prefer the c11.

I also enjoy taking phone images with the c11 as per the attached. 😀(Not proper imaging but I enjoy it)

 

[Datalord]

13 hours ago, MarsG76 said:

I don't think that it so hard.

I have about £11000 worth of personal experience it is hard. I bought my RC at 2400mm thinking my Celestron CGX could handle the weight, but the precision was simply not there. I ended up buying an ASA mount to be able to get good, consistent quality images out of it. Long FL astrophotography is hard. Very hard.

[msacco]

51 minutes ago, GavStar said:

I have both a c11 and a 16 inch goto dob. I note that several people have said go for the 16 inch dob, particularly for visual, due to the extra aperture, and I understand why.

But I think it’s also worth restating the obvious ‘the best telescope is the one that you actually use’ comment. I think this should be emphasised since a 16 inch dob is not easy to transport around imo. Ideally you would store it fully setup and then just wheel it out on wheelbarrow wheels. 

I use my c11 on a lovely panther TTS alt az mount and I find it very easy to transport and setup. In particular, the c11 ota is not that big or heavy and the mount packs away into conveniently sized packages. 

However, my 16 inch dob is a bit of a beast even though it’s a ‘compact’ version. With the mirror in place, the mirror box weighs around 30kg which is quite heavy to move around carefully - I now tend to move the mirror box without the mirror in it. And the footprint of the dob is pretty large - it’s not straightforward to pack into my Discovery Sport (and the back seats have to go down).

For my preferences, the c11 is much easier to setup and observe with (I also like the seated observing position of the c11 compared with standing for the 16 inch dob).

As a result, my c11 gets used many more times than my 16 inch dob and for this reason I prefer the c11.

I also enjoy taking phone images with the c11 as per the attached. 😀(Not proper imaging but I enjoy it)

 

Are these images taken with your phone? That simply looks amazing. Is that how you visually see these DSO objects with the c11? If so that's totally amazing.

[John]

18 minutes ago, msacco said:

Are these images taken with your phone? That simply looks amazing. Is that how you visually see these DSO objects with the c11? If so that's totally amazing.

They are acquired with the assistance of night vision technology. This technology enhances (greatly in some cases) what can be seen visually and imaged.

There is quite a cost to such technology in addition to that of the scope.

[MarsG76]

11 hours ago, vlaiv said:

Of course, you are right about that, but I did not recommend using 16" dob for DSO imaging - my suggestion was - if DSO imaging is an option, SCT + EQ mount is more sensible choice because one can later add small imaging scope to be used with EQ mount in that role. SCT would remain visual and planetary AP scope in that case.

I see your point too... ultimately the EQ mounted scope is the better choice as a potential all rounder... mind you tho, the 16" dob and planetary imaging firing crisp nights... oh mummma...