12" dob

[haznomad]

Hi everyone , im new to the forum and new to astronomy and am looking for a bit of advice in buying a new scope . I have stumbled upon " Andrews communications " thanks to this forum , they have a 12" Guan Sheng Dob selling for $799 , so my question is , is this as good a deal as it looks , or shoud i be looking at another brand of dob .

Many thanks

Haz

[alistairsam]

Hi Harry

I just had a look at the dob on the site and its. 12"F5 and for the price, I'd say its pretty good value for money. I'm not sure how easily it moves or if it sticks for small adjustments, these are best to try out in the shop.
But a 12 inch would be quite heavy. So do factor that in
Cheers

[Allan_L]

Hi Harry,
Welcome to Ice n Space :welcome:

Is this as good a deal as it looks? YES.


If you want a good easy to set up scope for visual observing, then this is a good deal (IMHO).

Only question I have is whether you will be comfortable lugging it around, being a 12" FULL tube scope.
Perhaps a bit extra to get a collapsible scope may pay off in the end if it is easier to move about. Or drop back to a 10"SW collapsible (flex dob) for the same price.?

[Irish stargazer]

The 12" solid tube dobs wont fit across the back seat of the average car. Check it will fit in your vehicle before deciding (if you plan to drive to a dark sky site). Thats why I went with the lightbridge which breaks down into smaller pieces (but optically it is of the same quality as the GSO-same manufacturer). $799 for a 12 inch scope is brilliant value.

[haznomad]

Hi again guys , first of all , many thanks for you replies , the size and weight of the scope wont be a problem as im only going to need to move it 3 or 4 metres on flat ground " i was thinking some kind of trolley system " and it will fit in my 4wd no problems , it is the quality overall that i was most concerned about , but its seems the people that make the scope also make other scopes and components , just re-labelled , looks like i may give this dob some serious consideration , thanks again folks .

[stephenb]

Just three castor wheels screwed onto the base is a goo mod to do! (see attached photo).

BinTel's range of Dobsonian telescopes are rebadged GSO telescopes. Nothing wrong with them at all.

I have owned 4 GSO dobsonian telescopes (8", 2 x 10" and 12") and for a beginner I would highly recommend them.

[Varangian]

Good large aperture scope for the price, best value scope in Australia IMO. I've had Skywatcher and Saxon Dobs I like my GSO the best. If you'd like to ask any specific questions or want more pics let me know. Cheers.

[erick]

You'll do just fine with that scope, Harry.

[barx1963]

I have a GSO 12" dob and some comment I can make
The Alt movement is really nice and easy to adjust, the Az movement can be a little loose, it will swing around in a decent breeze. Optics are good, but it is still a budget scope. One point is that the glass is BK7 not Pyrex. The collimation setup on mine was a bit dodgy, the springs simply not strong enough and the adjusting and locking screws pretty average. Replaced the lot with Bobs Knobs. I notice thaey now have large knurled knobs on the primary similar to Bobs, but the main thing is the springs.
The bases are just chipboard. I made sure I waterproofed the whole thing, superglued all the seams and siliconed where the parts joined. Haven't had any problems but it has never been really wet.

They often come without any instructions!!! Mine had a set but for the previous model which was put together differently.

Be aware that the tube is big and heavy, unless you enjoy carrying around a hot water heater, get a trollet to help move it around.

All that being said I have had years of enjoyment out of my 12". Great value for money, just be aware it is a budget scope.

Malcolm

[Varangian]

Edit. Duplicate post to Malcolm's above re. springs.

[haznomad]

Thanks for all of your advice guys , you have set my mind at rest that this dob is indeed a good first scope , i will contact the dealer asap to get things happening , will post again when i take delivery , maybe do a short review for others that may be considering the same scope , and of course i will probably have a dozen more questions for you guys .

many thanks

Harry

[CR500]

OK, so just how heavy is a fixed 10 or 12" Dob? I can fit one in my Prado with the back seat down, but can I lift one easily???

[Varangian]

I don't know how strong are you? Are you slight of build, quite robust?
A 10" is much lighter and less cumbersome than a 12".

Maybe look at trolleys for transportation purposes or put the Dob mount on castors and push it to the car???

[CR500]

OK, yes, I,m getting more and more robust every year.
I know they are cumbersome as far as dimensions, but any idea what the weight would be?

[Varangian]

Not the 10"

My 12" came in two boxes. The disassembled mount was 21 kg and the OTA was 21 kg so about 42 kg all up for a 12". So you are lifting no more than 21 kg at a time.

The 10" would be a bit lighter, but I'm not sure by how much, maybe around the 16-18 kg mark for each component???

[Cumbrian]

I bought my 10" GSO DOB from Andrews just over a week ago. I'm also a beginner, and despite having nothing to compare to, I am really pleased with it.

My scope is about 17kg and the base, I'm gessing, about 12-15kg. I carry mine up onto my rooftop and can do it relatively easily in two trips. I seriously doubt I could carry the 12" though.

Saying all that I'm jealous of you getting the 12"!

Jupiter was the best I've seen it tonight, despite very bad light pollution in Brisbane! As someone said previously though 1500mm is a big scope to lug about.

Enjoy.

[madbadgalaxyman]

Harry,
I would just like to reinforce the fact that a 12 inch is nearly always a large and heavy instrument, and therefore it is likely to be difficult to set up and use for the beginner.
A more practical aperture, for the beginner, is 8 to 10 inches.

It is remarkable how often beginners buy 10-12 inch telescopes, and then they find that the instrument is too difficult to lug around and to use, let alone to carry it to a dark sky site. I have seen these huge unused "white elephants" many times in my over 37 years of using many different telescopes.

I strongly urge you to read the discussion, in this forum, entitled "Recommendations for a beginner telescope", as it deals with the practical side of using telescopes of different sizes. The discussion entitled "Semi-beginner semi-first scope advice" deals with the options for some of the smaller sizes (4-6 inches).

cheers, madbadgalaxyman

[Steffen]

That's an interesting data point. The 8" GSO Dob (that a lot of people will be familiar with) weighs about 10kg for the rocker box and 10kg for the tube. So, both parts of the 12" Dob will weigh as much as the entire 8" Dob.

Also, keep in mind, what you can and cannot carry doesn't just depend on its weight. I could carry a 20kg tube easily, but a 20kg rocker box not so much, because of its awkward shape.

Cheers
Steffen.

[haznomad]

Hi again everyone , 12" dob was ordered at the beginning of the week so should arrive any time now , cant wait . Once again many thanks for your comments and advice . It would seem the only downside to this scope is its size and weight , its ok it wont be a problem , i intend to put wheels/casters on the bottom , to move it from where its going to live to where it will be used involves sliding a door open and rolling the scope 4-5mtrs on flat concrete , to get it in my car , i am able to reverse the Patrol right up to where it will live , so no carrying , just a lift into the back of the car . Thats the theory anyway .

Haz

[madbadgalaxyman]

Assuming the identical design, and assuming identical materials with identical densities, an object which is scaled up in dimensions by 50 percent, which is the (very) approximate case for the scaling up of an 8 inch into a 12 inch......
the 12 inch has to weigh three times as much as the 8 inch.
(if you double the dimensions of something, you end up with a volume that is 8 times greater!)

Now it is possible to save weight by clever design in the large telescopes, but, experienced amateur astronomers know that a 10 inch telescope is usually a "large and rather heavy object".....though there are a few exceptions to this rule.
Experienced amateurs also know that a 12 inch is always a massive object.

As I keep on saying in these beginners forums: "the best telescope is one that you are able to use frequently and easily, without great struggle and stress"

That is why I recommend an 8 inch Dobsonian for beginners!!

[Scorpius51]

Spot on, Robert!

[madbadgalaxyman]

When I was "growing up"(astronomically!) in the 1970s, way back when dinosaurs roamed the Earth, the biggest instrument we could usually afford was a 6 inch telescope. So we learnt to handle telescopes properly using smallish instruments and we learnt to observe using modest Light Gathering Power.

It takes time and effort to learn how to use telescopes and to learn how to use your eyes to observe. It is easier to do this with a 6 inch or an 8 inch than with a 10-12 inch.

We didn't have large apertures available cheaply, in those days. There was no temptation "to go too big", as anything over 6 inches was expensive.

I, personally, favour an 8 inch Dob for beginners, though I am aware that some of my fellow experienced amateurs would say "go for a 10 inch Dob". However, I know of some people (for instance some people of the female gender), for whom a 10 inch Dob is too big to handle easily.

[barx1963]

The question of the best beginners scope is a vexed one. Every individual has different wants, abilities, pecuniary resources etc so there is probably no one right answer.
I have only been seriously observing for about 5 years and in that time my scopes have been,
130mm Newt on EQ2 Mount
8" dob (loaner from the ASV)
Meade ETX 80 Go To refractor
12" GSO dob
15 x 70 Orion binos
20" Obsession style dob
Given this progression I can state that all other factors being equal ( and I will get to what I mean by that in a moment) the 8" dob is the "best" beginners scope.
I am a typical male in my mid forties (or I was when I had the 8") and I would hazard a guess that I am pretty much the typical demographic for beginners today. Also we usually live in suburban or light polluted areas and we are time poor.
An 8" is a little bulky and heavy, but not so much that is a chore to set up. It is tolerant of average collimation (I never touched it on mine after I got it). It is big enough to be usuable with moderate light pollution. It can be transported easily to star parties and dark sky sites. It is not so bulky that the beginners better half is unlikely to complain about the monstrosity in the living room.
It is easy to use, point it at what you want to see and there it is.
No electronics to go haywire.
I agree with Robert that small aperture can help hone observing skills, but with light pollution, the lower boundary of small has moved since the 70s. My older brother was an ASV member who used the 25" Cassegrain the ASV had in Burwood back in the 70s. Back then, Burwood was still outer suburban and still had reasonably dark skies. I would hate to try observing there thses days!!
The worst beginners scope is a small newt on a wobbletronic EQ mount or a small go to ( I have had both and know all about them) When I look at the online telescope retailer around these day and see these things in the beginners section I get so irritated. It only serves to drive people away from our wonderful hobby.

Malcolm

[Scorpius51]

Again, very true!



Ditto! A real frustration, but people get taken by purchase-fever.

I currently favour my 10" Dob over my 8", but only because the 8" is mounted on an HEQ5 Pro. The Dob is so much easier to set up AND USE, than the EQ-mounted 8" - both take two trips to set up.

However, if I did have an 8" Dob, then it would get used more than the 10", because I could lift the whole 8" Dob with mount in one trip. It would get used even more than my grab-and-go 70mm refractor - in this case aperture rules, OK!

I would LOVE to have a 12" Dob (16", even better :D), but I know that it would not get used as much as a 10", or 8". If I had to carry a hot water tank-sized Dob and mount out every session, then I would not be out as often as I am.

There is too much choice now, and it's very easy to fall victim to aperture fever, for a marginal benefit under normal city-based observing. There is a balance to be made between how often you want to observe, what you want to observe, and how convenient it is to observe. However, if you have a permanent setup, the 'rules' can change quite a bit!

The big driver here is motivation. If your passion for observing is greater than your concern for convenience, then go for it!

[madbadgalaxyman]

In the previous threads regarding "Beginners Telescopes" that I mentioned (in this forum), most people seemed to agree with Malcolm and John and Steffen and me, that an 8 inch Dobsonian is big enough to show decent views of the planets and deep sky objects, but not so big and heavy that the beginner is put off from regular observing or taking it to a dark sky site.

There were a few experienced amateur astronomers who thought a 10 inch Dobsonian was a good start for a beginner, because the deep sky performance of a 10 inch is a significant jump over an 8 inch, but you would have to be the sort of person who doesn't mind moving around a rather large and heavy and unwieldy object.

In any discussion of "beginner's telescopes" you also get one or two 'refractor fanatics' who insist that the optical quality of their small refractor is such that a four inch refractor is a good way for the beginner to start; but a telescope of under 5-6 inches of aperture is so very limited for deep sky viewing that you always end up looking at the same handful of objects if the sky is light polluted!

[barx1963]

That is the big point. An ideal beginners scope is one that shows enough that the beginner gets "hooked" but not so big/heavy/bulky/fiddly to setup that it is easier to stay indoors and watch My Kitchen Rules that get out with the scope.
When I had my 130mm as my only scope, the sheer hassle of polar aligning and then trying to navigate to find anything meant it sat unsued on many clear nights.
Once I had the 8" the clear nights without use were almost zero.

Malcolm

[Varangian]

Yes indeed. The 12" rocker box is very cumbersome, there's not much way around it if you have to lift it. I drilled some holes into the OTA up near the primary mirror end to assist with transportation of the tube. I removed the primary first to ensure no metal shards (or anything else accidental) landed on the primary. It's attached with bolts with lockable washers so it's not going to pry loose. The handle assists with moving the OTA from the shed to my car a great deal. The mount, well that's still cumbersome.