help please

[man on the moon]

I'm an intermediate amatuer astronomer, and currently own an 8" dob, but it is time to change. At first, I thought I should get a 12" meade lightbridge dob (http://www.telescopes.com/products/Meade_LightBridge_12_Inch_Truss-Tube_Dobsonian_-_Deluxe_42932.html), because i want to get into some deep space observing, and I could benefit greatly from a large apeture. But after looking around, i thought that mabye a 10" could also do the job, and i came across this: http://www.telescopes.com/products/Celestron_C10-N_GT_Reflector_15635.html and then saw this: http://www.telescopes.com/products/Meade_LXD75_SN-10_AT_-_wAutoStar_-_Standard_Coatings_28014.html. Now i am not so sure, i think that astrophotography would be interesting, but my brother is realy keen, and i do apreciate the goto and how equatorial mounts follow a stars path across the sky, but if this sacrifices too much aperture, then i could live without those comforts. Also, why is it that a 12" highest power is 600x and a 10" highest power is also 600x. I know of the rule 2x per millimeter, but that is what i have read everywere. If there is anyone from Australia, could you please tell me if the website the telescopes are on is in australian prices,thanx. Which of the three telescopes would you choose? And how much deep space work can be done with a 10"? I am particularly interested in galaxies. please reply soon.

clear skies!
:prey2: :prey2: :prey2: :help: :help: :help: :prey: :prey: :prey: :confused: :confused: :confused: :shrug: :shrug: :shrug:

[asimov]

Hi & welcome to IIS.

That depends on how 'deep' you want to go. With an 8" scope I would imagine it would do great on deep space observing. Seeing as you would use low mags for most DSO observing, a motor driven mount is not a necessity, but it's nice to have. When your looking at planets at high magnification, then you might class it as a necessity.

After saying that, aperture rules for Deep space observing! Get the biggest scope you can afford.

[man on the moon]

thankyou for the welcome asimov,
How deep can i go with each? I don't want to go as far as supernova searches, but would like to see most of the objects in the messier list, as well as most of the 100 brightest galaxies. I 'll probably go for a GSO dob rather than a lightbidge, because they are cheaper and i've only heard good things about them. Astrophotagraphy sounds fun, so this is why i am thinking about the 10 inchers, and it is just so much easier to let it fing the objects you tell it to find, rather than finding them yourself.I don't mind having to fing them though, as i will get to know the sky better, but it may get annoying for the fainter objects.
thanks for replying.:)

[mickoking]

You can see all the messier objects with an 80mm refractor ( some have done it with smaller instruments). Your 200mm Dob will show you thousands of DSO's and a 300mm instrument will probably show all NGC objects plus many more.

clear skies :thumbsup:

[davidpretorius]

8", 10", 12" or 16" dobs are all great and will give years of viewing. think of portability, what is your budget.

you can go fairly well with capturing planets at low magnification images, but t get the large scale, you need to motorise your dob or get a eq mount.

again what is your budget?

[acropolite]

When it comes to telescopes there's no substitute for size. If the 8 inch leaves you with hunger for more then I would suggest a 12 inch. If you're talking astrophotography a dob is really not very suitable, you would be better off buying some specialised equipment later for that task, for example an ED80 and EQ6 mount.

[asimov]

Or perhaps just buy the EQ6 & mount the 8" OTA on it.

[man on the moon]

These telescopes are at the top of my price range-well the most expensive ones any way (1200us):cool:

[janoskiss]

If you are not already "into some deep space observing" with your 8" Dob, then a bigger scope will not necessarily help you. How long have you had your scope? Do you ever travel to a dark site to observe? That will show you a lot more than a bigger scope. If you live under light polluted suburban skies travelling a distance of 60-100km away from the city is equivalent to somewhere between doubling or tripling your aperture.

An 8" will show you heaps of DSOs: all the Messiers in considerable detail, and lots of other objects; even faint ones like galaxies and planetary nebulae. The perceived difference in brightness from a 10" is slight.

The 600x cap you read for all the bigger scopes is due to ever present atmospheric turbulence.

[Starkler]

As Steve said above, the best thing you can do to enhance your deep space object observing is to pack your scope into the car and go for a drive away from city lights. Especially for low brightness extended objects such as galaxies and nebulae it makes a world of difference what you can see when viewing against an inky black sky sky as opposed to a milky grey one. From my outer suburban Melbourne home, I can only see the core of the brightest galaxies and a bigger scope wont help that.

The best upgrade one can do to a dob for dso work is to fit digital setting circles such as Sky Commander or Argo Navis. They are a small computer which allows you to select an object you wish to view, and it guides you to the object by telling you which way to push your scope.

Getting a scope on an eq mount is counterproductive to the portability aspect and for visual observing, the added weight, complexity and lesser sturdiness of the mount compared to a dob is a royal pain IMO. If tracking objects at high power is hard with your scope, spend some time on modding your scope to get the motions nice and smooth. There is plenty of info on the net about methods to achieve this.

My recommendation is to learn to get the most from the scope that you already have, before shelling out for things that may not be what you really want or need.

[man on the moon]

Thanks guys, i have done a little DSO in the past, and am going to do a little more before i get my new telescope. I don't usualy travel, and when i do, i only to up in the hills. My skies are relatively dark, but i can only see stars down to mag.5, to 5.5. The reason I am thinking about the lightbridge,is because it is more portable than the GSO dob. The GSO dob is less expensive than the meade, and i'll probably go 4 the delux model, but i was wondring how it compares to the optics of the meade, and why is the meade so much more expensive. I think the idea about the digital setting circles, but if i wanted to do that, i would probably go for something similar to the skyquest intelliscope 12", as it is alot cheaper than argo navis, but i shal look into the pricing of the sky commanders.

[Starkler]

Firstly, you wont get a Skyquest intelliscope in Australia as they arent sold here.

The Meade lightbridge uses optics sourced from gso, they are the same optics as used in the gso dobs !

Yes The gso dob is cheaper than the lightbridge, the LB is more portable, yet the LB doesnt lend itself to fitting digital setting circles :doh:

If a 12" gso dob will fit in your car the decision is easy ;)

[man on the moon]

thanks geoff, this is a great help, as i will now be getting the GS scope, it will fit, i'll make it fit...:wink2: :confuse3:
one last thing, i read somwerethat the GSO's limiting magnitude is 13.7, but the mead's are 14.5. whats up with that?:confuse2: :confuse2: :confuse2:

[janoskiss]

Sirius Optics sell Intelliscopes. Website prices here:

http://www.sirius-optics.com.au/Orion Dobs.htm

At those prices you'd probably be better off buying a GS or Synta Dob and fitting Argonavis.

Scope's limiting magnitude depends on visual magnitude, and the difference between visual and scope limits depends on pupil size so there is enough unknowns there to give an uncertainty of around 1 mag.