new scope

[JJDOBBER79 (Jas)]

Hi there,
I have a question for people who know more about scopes than I do. I am looking to upgrade from my 6 inch dob in a couple of months. I have a max of $800. I am thinking of getting the 12" solid tube dob from andrews for $750. My question is is there anything else that will perform (for strictly visual, deep sky) as good as this scope. ie cassegrain, refractor, mak cas? My very limited knowledge (mainly from reading on this forum) tells me the answer is no but I do like to get other opinions from people wiser than myself. Let me also say I know that this is a big scope. I am 6 foot 2, young and a large/fit build. I also have a large 4x4 with plenty of room in it. This in mind, my logic tells me that I should go for the largest aperture that my budget can afford. My understanding is that because of the mount, my budget will not get a decent aperture scope of any type except a dob. Do refractors generally perform better than dobs making a 6" refractor equivalent optically to say a 10" dob? I am asking this because I have a very limited understanding and no experience in using anything other than a dob. What do you guys think?

[Robh (Rob)]

Hi Jas,

You can't beat a dob for visual. It will give you the biggest aperture for your budget. A 6" refractor will only get you a quarter the amount of gathered light of a 12" dob. Light is crucial for observing galaxies and other faint objects.

Furthermore, a larger aperture will give you more resolving power i.e. sharper detail in objects you look at and that includes planets.

In any case, a decent 6" refractor will cost you many thousands of dollars.

Regards, Rob

[Tropo-Bob (Bob)]

Taking the 12" Dob out to a dark location in your 4x4 sounds near perfect for deep sky. Refractors can give good resolution (especially on close, double stars) and a nice image quality, but really for deep sky, aperture is the key to seeing more. When U can afford more, I would suggest upgrading the eyepieces.
I write this on the assumption that U have cut your teeth on current Dob and have located a number of globulars and galaxies and are now ready to progress to the next level.

[omegacrux (David)]

Hi Jas
Not long ago I had a 6in acro and a 10in Dob still have the dob
Viewing wise the Dob runs away from the acro , it is a lot better on most objects
Tuc47 , Omega Cent and Orion and most other nebulas , if you can handle it you won't regret tour decision

David

[JJDOBBER79 (Jas)]

Thanks for the input here guys. Looks like its a 12" dob. hopefully in time for xmas.

[glend (Glen)]

Jason, ANdrews Communications has recently dropped their GSO 12" dob price back to $749, which is very good for the optics package that you get. The eyepieces that are included with the scope are just adequate, but that scope really shines when you get some good eyepieces onto it. I have both the 12" GSO and the 16" GSO Truss dob and have no complaints about the optical quality of either. It's worth looking at getting a couple fo GSO Superview eyepieces with your scope; I love my Superview 30mm and 15mm EPs and use them far more than anything else in the kit. Best of luck with your new dob.

Lismore eh? There is a proposed Star Party/astro camp being talked about to be held at Lake Chaffey NSW (just east of Tamworth in the ranges) around the end of February 2014, might be a good chance to use it in really dark skies.

BTW, have a read of the articles section about Setting Circles, it makes finding things in the sky much easier if you have a setting circle on the base and a digital altitude (angle) measuring device on the tube. One like this is ideal:

http://www.ebay.com.au/itm/Digital-A...item484af7c29d

With a compass rose printed on the base and the altitude angle device you will be able to push to any object - provided you have Az/Alt co-ordinates from any of the free astronomy apps available today (SKy Safari is my personal favorite).

A bit of experience with manual Pushto and you maybe wanting to put encoders on the scope and go fully digital to give even greater targeting accuracy. There is a saying, that observation is 90% location and 10% observing, but using the manual or electronic Pushto setups can change that around to about 90% observation and 10% location.

[JJDOBBER79 (Jas)]

Thanks glen. I never considered the setting circles and altitude meter. That's a great idea. And I use star walk so can get coordinates. So, do you just stick the meter on the tube?. How accurate would this be? It would be great if it could get me a within a couple of degrees of a target. I tried to find the article about setting circles , did you mean the "build your own" article. I would probably prefer to buy them if useful. Thanks again.

[glend (Glen)]

Jas, that altitude meter (or digitial angle meter) has a magnetic base so yes it can just be stuck on the top of the tube and it will be accurate (provided you zero it on a flat horizontal surface before you stick it on - I use my kitchen counter top to zero mine. It will occasionally time out and go to sleep but turning back on will return it to the last leveled startup so it will still be accurate.

Re the azimuth circle, there are heaps of PDF files kicking around here and other forums (like Cloudy Nights) for various sized base circles. You will need to know the diametre of your base to know which one to get. Once you download the file, just take it to any Officeworks, or local printing specialist, and get it printed out in full size (which maybe A1 for large scopes) and then have it laminated. Depending on what sort of base bearing you have you will have to cut the circle to fit around the bearing and then stick it on the ground board with spray contact adhesive. You will need a little indicator marker to point to the degree number on the azimuth circle (I used a nail glued into a small hole I drilled in thepart of the mount that moves.

Just search for setting circles and you will get heaps of info. Not digitial setting circles as that tends to be more about encoders and not azimuth circles. You could search for azimuth circles as well.

Here is Richard's thread on his setting circles, with links to various PDF files of different sizes (just go through the thread until you find one right for you or contact Richard as he cuts files for people (at least I think he still does that). It's worth reading what other people did and look at their photos as it will give you a better idea than my words above.

http://www.iceinspace.com.au/forum/s...etting+circles


Have fun.