Regarding 12" solid Tube -Few Q's:

[-George-]

Hello,

I decided that I am going to get a 12" solid tube scope simply because I do not need to drive anywhere to use it and if I ever do (like star parties - extra fun factor) my Falcon Wagon can fit it no problem.

Having said that,

I looked at the Bintel 12", the GSO 12" (both $850) and Meade Light Bridge 12" (truss rod style - $1300).

Now what I want help with is, reality vs 'advertising'. When you read the more-info section on this scope:

http://www.bintel.com.au/Telescopes/Dobsonian/Bintel-BT302-B-12--Dobsonian/73/productview.aspx

and then

http://www.bintel.com.au/Telescopes/Dobsonian/Meade-Lightbridge-Deluxe-12--Dobsonian/74/productview.aspx

.

Now Bintel told me they are made in the same factory. Meade's advertisement thing says

"Meade optics consistently outperform telescopes of similar and larger aperture."

So it should be better than the Bintel even though same factory?
Better than the GSO - though same factory?

Real - or - Hype? (even if its 1% better, it is still something) I want to know is it 100% the same or is there a 1% or so difference?

Then it says this


• Meade Optical Coatings: Aluminum Coatings with durable silicon dioxide over coat provides bright images full of detail.

Doesn't say GSO or Bintel use this in the information.

Does that mean they don't use that, and hence why Meade is 1% or something better than other 12" scopes, or are they all coated with the same stuff, just different manufacturer 'promoting' different aspects of their scope?

Another question I have is:

Accessories, what would I need to get the most out of the telescope?

A year ago I saw this as the accessories needed:

1. 3 eyepieces with as large an apparent field of view as your pocket will allow
2. A set of collimation tools (I prefer Howie Glatter but Hotech is also good from what I hear. Stay AWAY from cheap laser collimators).
3. A O III filter for nebula.
4. A red light and a Pocket sky atlas to begin with the "obvious" targets, build up confidence and become proficient at using your telescope and understanding how it functions.
5. A Telrad.

I would call the above as the essential parts needed to get 90% out of your scope.

-

What is needed here?

When it comes to accessories I do not want cheap stuff. I have heard a lot of controversy over 'collimation' tools, what works in 'reality' and what costs a lot of money and doesn't do the job as good as something cheaper etc etc etc.

Help needed! When I collimate I want it to be 100%, not 99.9%.

What is a Telrad?

Please look at accessories offered between the 2 Meade and Bintel (perhaps a GSO from Andrews) and see which one seems to offer the most in that regard as well as to why buy one over the other.

Anyways thanks!

[Allan_L]

Hi George,
If you want the best, why are you not considering Orion or Skywatcher DOBs. (IMHO) I consider these outperform the ones you mention.

Where do you live?
Sounds like you need to get to a local observing night and look through a few various scopes (and accessories).

I can't answer the questions about differences in the mirror qualities, but my guess is that if they all come from the same factory, they are all made to the same standards. Perhaps there are some differences afterwards. You probably need to speak to someone who works there.

But I have heard some "experienced" users claiming that their GSO mirrors are exceptional quality. So I think you stand the same chance of getting "a good one" from them or their rebadged ones.

Differences probably arise in the accessories.
Obviously a 10:1 Crayford focuser is a benefit. But generally the supplied eyepieces are of similar good standard plossl quality.

Re your accessory list, this looks like a good list.
I have just recently bought a Hotech self centering laser collimator (with illuminated crosshair) from an the Astro Shop. And I have found it extremely easy to use and extremely accurate. I would have no hesitation in recommending it.

I have found that an observing chair also is essential. Steadiness at the eyepiece allows additional detail to be absorbed. And a Bintel type adjustable chair (although expensive) was well worth the investment in my opinion.

An oIII filter is good on many targets but some prefer a slightly broader bandwith filter. A UHC or a skyglow filter.
There are various comparisons around the net. IIS user Allan has been doing detailed comparisons (in his 12" full tube Orion DOB) for a while perhaps you could speak to him about his findings (why reinvent the wheel).

In stead of a pocket atlas I would recommend a Star Disc Planisphere.

I have tried Telrads on 2 of my scopes and didn't like them as much as a simple red dot finder. But that just gets you in the area, you still need the magnified finder scope. I highly recommend getting a right angled finder scope to save a few neck pains.

Additionally, a set of Bobs Knobs for the secondary adjustment is a good investment (saves messing about with an Allen key in the dark (over an unprotected primary mirror).
Bobs knobs for the primary may also be needed for some scopes but I think most are OK these days (check).

Good luck with your choices.

[glend]

I owned a GSO 12" solid tube dob and it was a very nice scope. I have looked through other 12" dobs but can't say one brand is much better than another but GSO mirrors are claimed to be good, as with any production newt some are maybe alttle better than others of the same brand. One thing in the GSO favour is the excellent altitude bearing which are also moveable balance points and have locking ability. These are roller bearings and not the teflon bearings used on some scopes. The GSO also uses needle roller bearings on the azimuth between two metal plates which is very smooth . I upgraded to the 16" GSO.
If your concerned about price, Andrews Communications is always cheaper for GSO products.

I am sure the mirror nazis will lob in shortly to rubbish production mirrors and suggest you need a mirror that costs more than most scopes but you have to start somewhere. Hwve a look at the limiting magnitude and resolving power of the scopes you are considering.

[astro744]

http://www.company7.com/telrad/products/telrad.html

[-George-]

Thanks for feedback.

The limiting magnitude and resolving power is the same on all of them...

[barx1963]

George
Further to your questions.
The limiting magnitude and resolving power is primarily a function of aperture with a bit more limiting magnitude if there is a major difference in coating reflectivity. So 2 12" scopes should show very similar figures here.
As far as the Meade versus GSO/Bintel scopes, yes they all come out of the same factory in Taiwan, so the optics and coatings are identical. I used a GSO 12" solid tube for years and was very happy with it. The big decision to be made is whether you want a truss tube and the price accessory mix.

With collimation tools, a lot of people (especially beginners) get hung up on collimation. Yes it is important to have a scope collimated, no it is not important that it be 100% rather than 99.9%. The amount of work required to get that last little bit is simply a waste of time that is better spent observing, or deciding on your next target or reading posts on IIS! When you get your scope, set it up, collimate it as best you can observe a couple of targets then turn one of the collimation knobs 1/2 a turn. Then have another look. If you can tell the difference ( and here I am talking about a 12" f5 GSO type dob or similar) you have better eyes than nearly everyone on the planet. I have done just this and the experiment helped me to be far more relaxed about collimation. By all means get good quality tools and take your time but stressing over 0.1% is just not worth it.
A good guide to Newtonian collimation is here http://www.astro-baby.com/collimation/astro%20babys%20collimation%20guide .htm

With charts, I used these http://www.bintel.com.au/Accessories/Books--Charts-and-Software/Star-Chart-Laminated---CD-ROM/655/productview.aspx for a long time before upgrading to Uranometria and found them excellent if used along with a planisphere.

A Telrad is a good idea, or a simple red dot finder. Helps you to point your scope at a bright star to commence a star hop.

OIII filters are best used on planetary nebs, a good one is very useful but I wouldn't consider it essential to start.

Eyepieces. Usually my recommendaton is to use the EPS that coem with the scope first. It is possible to spend a LOT of $$$ on eyepieces so you want to make the right choice. Usually the GSO/Bintel scopes come with a range of EPs with a 25mm plossl a wide field about 30-32mm and some shorter one. You will find yourself using the 25 most and they are usually not a bad EP (especially considering it is essentially free with the scope!). Once you know where your observing interests lie, you will be in a better position to spend your $$$ wisely.

Cheers

Malcolm

[-George-]

Thank you Malcolm.

Interesting read. I had decided today that I will get the GSO and explained that with the eyepieces it comes with, it will allow me to learn/see how each eyepiece works (the views it provides) and from there, as I get experience, I can then decide which 'expensive' eyepiece I want in given sizes (based on experience gained). I had even decided 3 cheap eyepieces that come with scope is better than 1 good one simply because it allows me to learn what particular size I tend to use more.

So I decided on a GSO 12" from Andrews wesbite. In fact, from what I read...

The mirrors come at 1/12 min, some come up to 1/16 wave length... (whatever that means, I assume how good the mirror is ground/smoothed over).

It also comes with a whole bunch of accessories.

Also includes a right-angle correct image 8 x 50 finderscope, 2" Crayford style microfocuser with 10:1 fine focusing, 2" to 1.25" adaptor, fan and premium GSO 9mm, 15mm and 25mm 1.25" fully multi-coated Plossl eyepieces!

BONUS GSO 2" SV30mm eyepiece!!


I think this is great, 4 different eyepieces to use and get an understanding of, the views provided etc before spending on Televue Ethos eyepieces for $750ea.

I will stop in there tomorrow to have a look!.

Btw - 1/12 - 1/16 wave length thingie... please explain what that is, and how good is that in relation to say a 'perfect' parabolic mirror that you spend a few good thousand on... just for 'reference' sake.

Also, when you refer to 'red dot' for star hopping... sorry for the dumb question but, I have a picture in my mind of a hand held laser pointing at the stars and some how you should see a red dot on the sky like when people point lasers at a Cinema screen... some how I doubt you are saying that but that is what is in my head...

[Steffen]

I wouldn't expect to see any floor stock on display at Andrews in Greystanes. He has a few bits and pieces on display but doesn't have a showroom like Bintel. I've never seen an assembled Dob there.

Best to give them a call before you go.

Cheers
Steffen.

[glend]

Agreed, talk to Luke. One reason they are cheaper is that all that stock is back in the warehouse, and they ship from there, they have limited room for floor displays. Bintel pride themselves on being a little more helpful to newbies (and maybe that is a reason for the price difference) whereas Andrews assumes more knowledge on your part. However, I have always found Luke to be very helpful with anything you want to ask. Don't forget to ask about delivery charges from both.

[astro744]

This is the wavefront error. See http://www.telescope-optics.net/aberrations.htm for more information.

Note the manufacturer must state whether 1/12 or 1/16 is peak to valley or average to peak. The difference is 2x.

Note I normally deal with BINTEL and I know the staff there know their products very well. The pricing is reasonable and after sales service second to none.

[barx1963]

George
I am not sure what happened with the link I had in the previous post, I have edited it so it should now be http://www.astro-baby.com/collimation/astro%20babys%20collimation%20guide .htm

Cheers

Malcolm

[Allan_L]

A Red Dot Finder is a small gizmo that projects a red dot onto a clear screen that you look through to align with an object of interest.

A Telrad is derived from old fighter squadron targeting system, is much bigger, and projects various sized circles that you align with the object.
The circles represent different field of views.

Both are unmagnified views.

Hope this helps

[-George-]

http://www.opticscentral.com.au/saxon-12-inch-dobsonian-telescope.html#.U0HohPU_7JE

What is this saxon like? Offers less accessories, 2 EPS instead of 4, 1300 instead of 850. Uses pyrex mirror not BK7.

And Faintest Steller Magnitude15.4 Resolving Power 0.56.

is faintest stellar the limiting magnitude?

GSO says Resolving power; 0.38 arc second.Limiting magnitude; 14.9.

$450 difference. Is the resolving power accurate for both etc... ?

[alistairsam]

hi George,

I don't think the difference would be significant enough to justify the $450.
I believe both are mass produced.

If you are prepared to pay a bit more, I'd suggest you look at investing for added convenience, collapsible Dobs that make it easy to transport and handle than a solid tube. Its more for portability and ease of storage but goes a long way.
http://www.myastroshop.com.au/products/details.asp?id=MAS-041G

I know you mentioned you don't need to travel much with it, but my point is that from the $850 solid tube, the only reason to spend more on the 12inch would be for the truss convenience (compactness when travelling) or the collapsible tube convenience (again compactness) or even goto capability with a motorized Dob.

But comparing two solid tubes with the same dia mirror but $450 apart, the saxon one doesn't make practical sense to me.

so if you're happy with handling a solid tube, the GSO is very good value for money.

I remember viewing eta C through a 12inch SDM at Snake valley.
I've never seen anything like what I saw through the EP. it had a 3D depth to it, was crystal clear and so much detail.
I thought it must've been a hand figured mirror because SDM build premium scopes with custom mirrors.
But what I didn't pay attention was that the Eyepiece was a premium one, don't know which, but was amazing and the mirror, to my surprise was a GSO one.

I'm no expert, but I believe hand figured mirrors offer better views but how much better, all depends on what one's after and how much you can discern.

Things like dark skies, eyepieces, mirror cooling make a lot more difference.

Point I'm trying to make is that to spend $450 more on the same aperture, the reason has to be better than what's advertised in terms of magnitude and resolving power, especially if both are mass produced.

Cheers
Alistair

[-George-]

Thank you. I was just at Andrews optics. Spoke with Luke. The GSO actually has a better mirror than the saxon. 0.36 arc resolving vs saxons 0.56. And i get 4 eyepieces with the GSO while saxon only 2.

So im paying 450 less to get a better mirror and 2 extra eyepieces. Thats the logic I like!

Want to thank thr members here, starting with Alex who i spoke to first because I never heard of GSO until now and thats awesome value for money. 1-2 weeks i should have it!

[AG Hybrid]

What?

No really. What?

This thread (through no fault of George) is becoming one big mind****!

The problem is retails are making up numbers. You should ignore the figures any retailer gives and refer to the manufacturers specifications directly. The Saxon's which I understand are Skywatcher/Synta scopes with said optics are actually 305mm diameter a little bit larger than the GSO 12" mirrors. If anything. Resolution, although a tiny and unappreciative edge goes to the Skywatcher.

Choosing between 12" scopes in limiting magnitude and resolution is a completely pointless. They're sensibly identical and you can't tell the difference in the eyepiece. Poor collimation, poor mirror ventilation, atmospheric conditions, local seeing and observing conditions will limit resolution and limiting magnitude long before a 12" scope hits top gear.

If you're going to choose between 12" scopes. Look at price, features and included accessories instead.

That being said. The 12" you ordered from Andrews is a great scope. Congratulations.

[-George-]

Double posted.

[-George-]

O, i asked about delivery charge.$0. They will bring to store when im ready and put it in my car. No drama there. Luke did say the difference was insignificant between then in terms of arch, i just mentioned it to him and so he tried to explain the difference. More or less MAY make a difference if astro imaging but then, its a dob mount that you dont use for that anyway, so other factors are far more important. He said i was splitting hairs.

[Allan_L]

Congratulations.
Sounds like you made a good choice.
Enjoy!

[Steffen]

I didn't know the Saxon Dobs used pyrex mirrors, this would be a substantial advantage in a 12", IMO.

Cheers
Steffen.

[barx1963]

Sorry but I agree with Allan. Limiting Magnitude and resolution are a function of the mirror size primarily. Yes there are "better" 12" mirrors but the effects show up in less aberrations (eg spherical aberration, astigmatism etc) or the quality of the coatings not in large differences in the limiting magnitude and certainly not the theoretical resolution of the scope.

Malcolm

[-George-]

either/or, I am just very happy that I got something good for a price that is perfect to learn on. As I gain experience over a fear years, then I can look into something like $3000+

For 850, can't go wrong as an instrument of education and yet still get a lot of joy as the quality will be fairly good and it gives me more eyepieces to play with to learn what sizes I find myself using. So to me, it offered the most tools to me to learn on while providing something of pleasing quality for a price that is perfect to start on.

[barx1963]

Don't get me wrong I am not saying there is anything wrong with the purchase, I had a 12" GSO for years and loved it (only sold it last year as I had no room to keep it anymore!)
The issue I have is with retailers and makers making some odd claims about properties of their scopes

Malcolm

[SimmoW]

George, I picked up my Meade Lightbridge on Sat!

I haven't got a huge station wagon nor heaps of storage, so i had to get a truss version. See my blog for pics. An unexpected advantage is the lightness of each piece to carry.

The default red dot finder is frustrating, impossible to adjust l. I'll probably try to swap for a Telrad. can't believe the red dot finder is more expensive than the telrad. But these scopes focal length is very long, so I suspect we will also need right angle finder
scopes. Plus they let in so much light there are too many stars, so it's hard to navigate! You're gonna love your 'bucket!

I love my Televue EP collection. But on Sat I tried buying a 42mm Bintel eyepiece, $59. Bargain of the century, well made and a vista of a view! I didn't think its quality was substantially less than the TVs.

Have fun with your new scope.

[-George-]

Thanks Simmon,

The GSO comes with a right angle finder. I will see how that goes.

[noeyedeer]

just remember that the right angle finder is correct view. so when you go from finder to scope it will be inverted. kinda tricky at first but you will get the hang of it.

matt

[-George-]

Telescope sees everything upside down?

Is there anything I can buy with this scope to make that the right side up (like Binoculars)?

[astro744]

Yes but it will degrade the image and don't waste your money as you don't need it and wont use it. Just turn your head. You will find depending on where something is in the sky will determine it's orientation. In any case if you are comparing to a map just spin the map around.

The field of view in your telescope will be considerably narrower than your unaided eye so using the horizon as a frame of reference is pointless.

If you are looking at something low in the east with your back to the north the image rotation will be different to if you look at something at zenith. What if you look east with your back to the south? In fact look at something at zenith with your back facing east, west, north, south and see what happens to the image. Which is correct? Which is right way up?

Note this is an astronomical telescope. If you plan on using the telescope for terrestrial then you will have to have your back to the object (not covering the aperture) and have the telescope level.

[Allan_L]

Actually, this makes the image right way up! (from a certain point of view)
From the southern hemisphere, we see everything upside down compared to those in Northern Hemisphere. (eg Orion is on his head)
And as most astronomy books are written from a US perspective, this should line us up with their view. ;)

Anyway, in space there is NO "Right way Up".

[-George-]

But...

Am I not seeing all the detail backwards to the way it should be seen?

I mean if I have to move scope to the right to see something on the left (because everything is in reverse order), how does that work?

That is putting everything upside down in the brain rather than the way it should look (If I could see it with my naked eyes)?

[astro744]

No. Even number of reflections = corrected image (may be upside down but not reversed).
Odd number of reflections = reversed image.

Upside down is not reversed.

An upside down image will match a star chart. A reversed image will not.

[barx1963]

The secret is not to worry about it. You will get used to it after an hour or so. I found best thing was to have a correct image finder so it always matched my charts and then stop worrying about it!

Malcolm