First Scope: 12" GSO

[PetarB (Petar)]

I've been a naked-eye and binocular observer since the age of 8 (i'm now 37) and its time I bought myself a scope. Recently, when just making out the the moons around Jupiter through my binoculars, I've been itching to see more. And as for those deep sky objects...

So to dip my toe in the water I've decided to get a 12" GSO Dobsonian. The collapsible Skywatchers looks good, however the mechanics of the collapsibles makes me think they will have to be collimated a lot, in relation to a rigid tube. The GSO seem to be good value for money too.

Any advice on these scopes? Any 'gotchas'? From what I read, 'stiction' seems to be an issue for the mount.

I imagine I will get a Telrad, is this the best finder for this size/type?

I will probably do most of my observing from my backyard... I'll have to move the scope out a few metres when observing. I hear a lot of complaints about moving these size scopes but I'm pretty fit. Perhaps I could build some sort of trolley?

Anyway, I look forward to any advice and insights...

[jamespierce (James)]

Don't let collimation scare you off a truss dob, you will need to do it regularly with a solid tube dob too. For any truss dob it's just a quick part of the setup routine, I hardly even notice doing it with my dob anymore. A 12" solid tube is pretty big to fit into most cars.

Otherwise, yes, get a Telrad and a copy of the Pocket Sky Atlas. After that invest in just two good eye pieces - something around 50 to 70x magnification and something around 120x to 180x.

[mental4astro (Alexander)]

Hi Petar,

A 12" dob as a first scope! Way to go!!!

First, have you seen one of these puppies up close? They are BIG.

I always say to those who don't have experience with scopes or a particular style of scope, to get yourself to a star party, hosted by an astro club or one of the many listed in the Star Parties forum, and see these fellas in action.

There is a reason why collapsible/truss scopes exist - big apeture solid tube scopes are enormous. The Skywatcher collapsibles have a proven track record for reliability.

"Stiction" is a technical term that relates to the delicate balance between the force needed to get the scope moving to overcome the grip that the bearings hold on the scope, and then the reduced force to continue on with the smooth motion of the scope. It doesn't describe a 'problem', and I can see how this term can cause confusion.

If the force required to overcome the grip of the bearings, there are various ways to overcome this- clean the bearings and the bearing surfaces; if the bearing surface is a 'laminate' type then an application of all things, car wax, does wonders for reducing friction. These methods apply to both commercially made and DIY made scopes (dobsonian mounted I'm talking about).

Before you go about changing finders or any other bits and pieces, use what the scope comes with. The Telrad is a fine finderscope, but it doesn't suit everyone. There is always time to change. Even better is to go to a star party, with or without your scope, and have a look at these gadgets and maybe have a go at using them too. Each has various pros and cons that each persons needs to feel comfortable with.

Don't rush into purchasing a scope. The stars ain't going anywhere. Your enjoyment of them will go quickly however, if the chosen scope doesn't meet your expections.

Mental.

[wavelandscott (Scott)]

Collimation is a way of life for a reflector user...a solid tube may hold collimation pretty well but to get the best from your scopoe you should check it every time.

As noted, soon it becomes a part of set-up.

If you've not had a chance to see the size of the scopes you are considering I'd encourage you to stop in to a local Astronomy Shop and check them out in person...seeing is believing.

One of my favorite shops in Sydney is BINTEL...there are some others too. Alternatively there are a number of IIS Members in and around Sydney...get to a viewing night to see some scopes in person.

[andrew2008]

Originally Posted by jamespierce

Otherwise, yes, get a Telrad and a copy of the Pocket Sky Atlas. After that invest in just two good eye pieces - something around 50 to 70x magnification and something around 120x to 180x.

Good advice about the eyepieces but i will just add a good barlow as well. Just be careful to get eyepeices that won't double up on magnification. For example a 24 and 19 mm panoptic barlowed will give 12 & 9.5mm. This would be a great range of 62.5x, 79x, 125x & 158x.

[Brian W (Brian)]

Simple advice... there is a learning curve and what you see now will be nothing compared to what you will see when you get in a little training. As was mentioned a 12" is -big-. You might consider a hand cart for moving the beast.

Also I highly recommend a -pirates eye patch-. After an hour or so of keeping one eye closed it can be tiring. You will never find a less expensive addition to the passion that will improve things so much.
Brian

[Davros (Lauren)]

Good choice, the view in a twelve inch Dob will leave your jaw on the floor. I have a solid tube 10 inch and i love it.

[Pi]

I just got the GSO 12" (arrived on Xmas eve ) and recommend that you check one out in person before buying, as before mentioned, it is BIG. (Look at some other sizes too)

Setup it stands around 1.6m tall and the base is 635mm in diameter. Just the OTA weighs 22kg, I certainly can’t pick it up length ways like I can a 10”. In my opinion, you NEED a trolley because the base has only one handle and I can’t figure a way to pick it up solo. Without my trolley the only way I can move the scope assembled is by dragging it. That said, with the trolley I deem the chore of moving it outside negligible and that includes four steps off the patio.

Optically it’s fantastic however the limiting factor for me is light pollution. The only justification for getting a scope this big is if you are going to use it at dark locations so if you live in the city consider how often your lifestyle will permit you to transport 40kg of optical equipment.

All in all, I’m loving the beast!

[PetarB (Petar)]

Went down to Bintel (Sydney) today and had a gander at the 12". It certainly is a little larger than I expected... but that's okay. I'm already planning how I am going to put castors on the base to move it around (won't need to move it around much).

I live in an area where light pollution may/may not be an issue (Sydney's Northern Beaches) since on my east it's the ocean, west is a national park, and the south is the city. But I'm prepared to take the risk.

I just need to work out where to keep the damn thing. Plenty of room, just working out where's most convenient!

I doubt I will be able to use it properly for a couple of weeks, holiday and work are going to interfere, but once I've put it through its paces I'll let you know how it goes, but I'll post again once I can do an 'out of box' review.

Now I know these sorts of scopes are not perfect for planetary viewing, but what sort of eyepiece should I be looking for?

[PetarB (Petar)]

Drove the 12" home with a big smile on my face. Took around half an hour or so to set up. I bought some castors for the base, which I will install shortly, I can see for my set up I will need them.

Anyway...

I am actually going on holiday tomorrow so I will be away for a week or so, but I couldn't resist trying her out tonight

I set her up and decided once twilight fell to align the finderscope on the brightest star earliest. I could tell immediately through the finderscope what I had suspected was correct. I was looking at Jupiter.

With a low power lens I aligned the two scopes.

Then I put in my Orion Planetary 5mm eyepiece... woah, I could see Jupiter's cloud bands and I could go on but you all probably know exactly what I saw. And this was at only 7.45pm or so.

I went out later, and put in the 32mm wide field and aimed straight at the great nebula in Orion. Heavenly!

And it's not even dark, or winter, etc, etc...

I'm hooked.