Beginner considering 6" or 8" Dob

Wowbagger · #1 14-12-2009, 06:40 PM

Hi all,

I'm about to reach deep into my pockets for the first time so I can hopefully reach deep into the sky. I am a beginner, in that I've only ever owned a dept. store scope that could barely see the moon with clarity. Now, after weeks of researching and procrastination (and saving), I am just about ready to fork out for either a 6 or 8 inch Dobsonian. But I have a couple of questions I want to ask.

The first question is this: should I get a 6" or 8" scope to begin? After much research, I do realise that this is a bit of a stupid question, bigger is better, so get what I can afford... but the 8" would be stretching my budget to the limit, the 6" might leave some room for accessories if needed. Am I better with a 6" + filters and eyepiece? or should I start big with an 8" using default accessories (and maybe get accessories down the track)? I have been looking at the SkyWatcher SW580 and SW680 (6" and 8" respectively), because they seem well priced and recommended.

Just a bit more on this subject, as a complete beginner, will it actually be EASIER to use a smaller scope? ie. do the added deep sky benefits of the 8" result in more difficult operation? Is it a bit like buying a Ferrari for a first car?

Finally, living in the suburbs of Sydney with terrible light pollution (can't see that many stars), will either of these produce better or worse images because of this? And further, would the 8" be much more difficult to lug around in my small Toyota? They both have a focal length of 1200mm due to the f ratio, does this mean the tube will be exactly the same length on both?

Oh yeah, and in case your wondering what I want to see, the planets (jupiter & saturn) in particular, but maybe even DSO's if I get good enough.

Sorry about a long initial post, and please go easy on me if any of my questions are rediculous

Finally, I just want to say that this is a great site, in my first few weeks of research I have found myself back here on numerous occassions from Google, which is why I finally decided I should join and pick your brains in person.

torana68 (Roger) · #2 14-12-2009, 06:54 PM

[QUOTE=Wowbagger;534362]Hi all,

The first question is this: should I get a 6" or 8" scope to begin?
yes 8 "

should I start big with an 8" using default accessories (and maybe get accessories down the track)?
yes, bonus of better resale as well

Just a bit more on this subject, as a complete beginner, will it actually be EASIER to use a smaller scope?
no, it would be lighter and smaller physically if thats important

Is it a bit like buying a Ferrari for a first car?
more like wanting a Ferrari and buying a daihatsu

Vartigy · #3 14-12-2009, 07:04 PM

Hi Wowbagger,

Wasn't too long ago that I was asking the very same questions.

8" is a fantastic place to start at.

Consider the truss mounted collapsable model. Easier to transport and handle.
Slightly more expensive?

Theres a few great name brands out there too. Guan Sheng and Skywatcher are some of the common names being thrown around these boards.

Being in Sydney I imagine you should have access to some great telescope and optical shops. They'd be a great place to start, get a look and feel for everything in your price range.
Then maybe come back here and seek out people that actually have those telescopes, and if they live near you, chances are you might meet them at a star/astro club meeting and try out one or two.

Telescope purchasing is not something that should be rushed into. Like marriage. Buy the wrong one, and your bound to get no action at night.

erick (Eric) · #4 14-12-2009, 07:08 PM

Buy the 8" The supplied eyepieces and extras will do just fine. As you save more dollars you can buy more items. You also may wish to DIY improvements to the supplied unit. Lots of ideas in the forum pages.

Robh (Rob) · #5 14-12-2009, 07:16 PM

There is significant light gain of the 8 inch over the 6 inch.
8^2=64, 6^2=36.
64/36~1.8 or nearly twice the light gathering ability.
Dimmer objects will be easier to see with the 8 inch, even under skyglow.
Go for the 8 inch!

Regards, Rob.

Wowbagger · #6 14-12-2009, 09:10 PM

Quote:

Originally Posted by anfo

Telescope purchasing is not something that should be rushed into. Like marriage. Buy the wrong one, and your bound to get no action at night.

Good advice... very profound! Unfortunately, the collapsible 8" is about as available to me as Angelina Jolie for a wife.

In fact, thanks to all of you for the (prompt) replies... there is an obvious trend here, which is that I should buy the 8" - and the unanimity has made up my mind, so I'll pop into a shop tomorrow and have a look at the SkyWatcher SW680.

Quote:

Originally Posted by Robh

8^2=64, 6^2=36.
64/36~1.8 or nearly twice the light gathering ability.

Is this equation to figure out the area of the mirror? Wouldn't it be PI*R^2? I only know basic maths, so it's likely I am missing something of your equation.

mental4astro (Alexander) · #7 14-12-2009, 09:21 PM

In the area equation, pi is the common factor between the 6" and 8" comparison, so they cancel each other out. Good pick-up though.

Tyre-kick if you can before you lay your money down and take your time.

I've PMed you too.

Mental.

Wowbagger · #8 15-12-2009, 03:27 PM

Hi all,

Can anyone give me advice as to Bintel telescopes? There is an 8" Dobsonian equivalent to the SkyWatcher SW680 called the Bintel BT202-B (for the same price).

https://www.bintelshop.com.au/Product.aspx?ID=8147

Has anyone used a Bintel scope? And can they vouch for their quality? Or should I stick to a more common brand such as SkyWatcher?

barx1963 (Malcolm) · #9 15-12-2009, 06:31 PM

The Bintel Dobs are simply rebadged GSO dobs (same as Andrews sell), really the only diff usually is the set od accessories that come with it. There is nothing wrong with these scopes, very good qualoty for the money, and both GSO (Bintel) and Skywatcher are made in China. The SW collapsible dob is the next level up. If the 2 you are comparing are just both 8" dobs, personally I'd buy on price.

Robh (Rob) · #10 15-12-2009, 08:00 PM

My brother has the BT202 Dob. It is great value for money and BinTel does have good backup service. Given the same eyepieces, I doubt that you would discern the difference between it and any other 8" Dob. It's just your personal preference and what accessories you get with the Skywatcher in comparison.

Regards, Rob.

Wowbagger · #11 15-12-2009, 08:11 PM

Quote:

Originally Posted by barx1963

If the 2 you are comparing are just both 8" dobs, personally I'd buy on price.

This is exactly what I did and as a result, I am now the proud owner of a brand new GSO 8" Dob (GS-680) which I bought from Andrews

Unfortunately, it came with no instructions at all, so I am unable to put it together until I can track some down.

Does anybody know if these instructions are published online anywhere? Or if someone has them and could post them here that would be great!

Otherwise I'll chase up the shop I bought it from and see if they have them.

Liz · #12 15-12-2009, 08:16 PM

Quote:

Originally Posted by Wowbagger

This is exactly what I did and as a result, I am now the proud owner of a brand new GSO 8" Dob (GS-680) which I bought from Andrews

Unfortunately, it came with no instructions at all, so I am unable to put it together until I can track some down.

Does anybody know if these instructions are published online anywhere? Or if someone has them and could post them here that would be great!

Otherwise I'll chase up the shop I bought it from and see if they have them.

Hmmm .... I think the GSO Dobs are renowned for coming without set up instructions .... as mine did. Be brave and give it a go - I found the trickiest bit was the mount - everything else should fall into place after that.
Also ... I think I may have downloaded a manual from another simliliar brand which helped. good luck!!

barx1963 (Malcolm) · #13 15-12-2009, 10:14 PM

Quote:

Originally Posted by Wowbagger

This is exactly what I did and as a result, I am now the proud owner of a brand new GSO 8" Dob (GS-680) which I bought from Andrews

Unfortunately, it came with no instructions at all, so I am unable to put it together until I can track some down.

Does anybody know if these instructions are published online anywhere? Or if someone has them and could post them here that would be great!

Otherwise I'll chase up the shop I bought it from and see if they have them.

Mmm.. I had the same prob I must confess, muddled my way through it with a bit of trial and error. It did come with instructions but for the old model that had teflon bearings and springs. I did keep a set of photos that show all the bits to my 12" and the final assembly. I can email them to you with some helpful hints if you PM me your email address.

Malcolm

Wowbagger · #14 15-12-2009, 10:57 PM

Well, I gave it a go and it seems to work like a charm. It is moving nicely on all its axis... so I can only assume I put everything in the right place.

Now I'm busting at the seems to look at the sky, but all I can see is clouds!

mental4astro (Alexander) · #15 15-12-2009, 11:05 PM

Mate, congrats on the new scope,

.

If you are interested, the word is 'Go' for a final astro bash at Randwick Girls' High School this coming Sunday night. If you can make it, do bring your new scope.

Robh (Rob) · #16 16-12-2009, 08:20 AM

Quote:

Originally Posted by Wowbagger

Well, I gave it a go and it seems to work like a charm. It is moving nicely on all its axis... so I can only assume I put everything in the right place.

Now I'm busting at the seems to look at the sky, but all I can see is clouds!

Well done and enjoy!
Cloudy weather is very common for new telescope owners.

I had to wait months for a decent view when I bought mine. But I think you might get lucky!

Regards, Rob.

Wowbagger · #17 16-12-2009, 01:55 PM

Quote:

Originally Posted by mental4astro

Mate, congrats on the new scope,

.

If you are interested, the word is 'Go' for a final astro bash at Randwick Girls' High School this coming Sunday night. If you can make it, do bring your new scope.

Thanks all for the hand holding through a scary process for me of buying my first scope.

mental4astro, that sounds great... I can't guarantee I'll be available Sunday night, but I will definitely let you know in the next couple of days. I'm certainly keen, I'm sure there is a lot I can learn about the sky and my new scope by gazing with some experienced heads!

DiamondDust (Ingrid) · #18 16-12-2009, 03:08 PM

Hi

, Sorry I got onto your thread too late, I could've emailed your assembly instructions, I've got the 10" (GS 880). If you need an operational manual (idiots guide

) to start you off, Dave Reneke found me a Celestron Dob Manual and a Dobsonian Manual on the net, they just about cover all you'll need with your GS. PM me with your email address and I'll forward them if you want, they're very helpful. Good luck and good seeing.