G'day all. Have been happily peering through my 20 X 80 nokkies for about 12 months now but feel myself being gradually consumed by the irrational idea of buying a telescope. As I've been thinking about it for a while, I've come to the conclusion that a 10 or 12 inch dob would suit my purposes quite nicely. Given that the price difference between the two can be up to a couple of hundred dollars, my question is this - Does the extra money translate into measurably superior viewing? My gut feeling is to go with the 12 inch. Is that rational or is that just aperture envy? Any thoughts or comments would be appreciated.
I've a 10" f4.66 newt , and it's akward enough to getting in and out the Pajero , seeing in my backyard is hopeless.
Difference in it between a 10" and a 12" is not a lot in resolving power, or reaching power (faintest star you can see).
12" has only 1.5 as much area to collect the photons than a 10" , a 14.5" has 2.1 as much area to collect the photons than a 10".
Under excellent seeing
Limiting vis mag is 14.5 for a 10"
Limiting vis mag is 14.9 for a 12"
Limiting vis mag is 15.3 for a 14.5" (nearly 1 mag gain over the 10") , well even if you can't get within a magnitude of these in reality in most cases , you get the picture. Uptake ... not much between a 10" and 12".
When I upgrade , I'll go to a 14.5" newt , seems a good size to me.
..buy the 10" now... at the rate the prices are going (and new truss jobs coming) you'll get the 12" for $300 in 6 months
Just expanding on Omnivorr's comments:
- 10" f/5 dob tube will typically fit across the backseat of most medium cars
- a 12" dob tube typically won't
So if you want portability for the occassional dark sky site visit (a treat not to be missed, especially in the mild/warm months), then I would recommend a 10" conventional dob.
If you go larger, I would suggest a truss-dob (eg. 12" f/5) ... but they cost more. I have compared my 10" Lightbridge truss-dob and a 12" GSO conventional dob side-by-side on DSO's at a star party and could not see any differences except for some very faint galaxy smudges which were a little easier to pick up in the 12".
I would go for the 10" and head north out of Alice on new moon weekends.
I used to visit my parents in Alice and drive about 15km north for dark skies.
The 12" shows more galaxies but it is less portable.
I use my 10" for weekends away and my 12" in an observatory when I am home.
I used to have a 12 inch GSO DOB, now sold. However, it used to fit no problems into the back of my Hyundai Excel with the back seat down; and fitting through the hatch.
The front seat was still useable so still enough room for my daughter to come with me.
My thanks to all who have responded. I knew I could count on IIS members for helpful advice. Portability of this thing shouldn't be a problem as my position 15 km SW of Alice in a semi rural area means I'm getting nice dark skies so the majority of my viewing should be of the backyard variety. A 20 meter shed right next to me stuffs the Eastern horizon somewhat but I can always drive about 1 km down the road to the claypans where the viewing is virtually horizon to horizon. I've got the trusty old Falcon uterus and I figure there's enough room in the back of that (1650 mm with the tail gate up) to transport most scopes.
So it really does come down to a simple question of whether or not an extra 2 inches of aperture is worth another 200 or so dollars.
Had to chuckle at Ian's reply though. Here's me trying to avoid aperture envy and a man obviously riddled with it slyly advises me to go with a 14.5 inch!
All the same Ian, what you said and the figures supplied confirm this as actually very cunning reasoning. I'd be very interested in hearing from you if you do upgrade, but I think that size might exceed my budget
Thanks to all for posting. You've given me a bit more to think about.
My thanks to all who have responded. I knew I could count on IIS members for helpful advice. Portability of this thing shouldn't be a problem as my position 15 km SW of Alice in a semi rural area means I'm getting nice dark skies so the majority of my viewing should be of the backyard variety. A 20 meter shed right next to me stuffs the Eastern horizon somewhat but I can always drive about 1 km down the road to the claypans where the viewing is virtually horizon to horizon. I've got the trusty old Falcon uterus and I figure there's enough room in the back of that (1650 mm with the tail gate up) to transport most scopes.
So it really does come down to a simple question of whether or not an extra 2 inches of aperture is worth another 200 or so dollars.
Had to chuckle at Ian's reply though. Here's me trying to avoid aperture envy and a man obviously riddled with it slyly advises me to go with a 14.5 inch!
All the same Ian, what you said and the figures supplied confirm this as actually very cunning reasoning. I'd be very interested in hearing from you if you do upgrade, but I think that size might exceed my budget
Thanks to all for posting. You've given me a bit more to think about.
Hey there Dogstar!
I guess you got my pm about the prices on the dobs at Andrews over the weekend after all.
I reckon 10" or 12" you'll love it, but whatever you do don't get one with a Rack & Pinion focuser, get at least the standard Crayford, the R&P's are so frustrating to reach a clear focus with.
Having said that I'd really recommend that you get a scope with the 10:1 Crayford on it, when you're chasing clean focus at higher magnifications to see planetary detail, etc, you'll want it.
ie go 10" at $499, or 12" at $749
(I originally had the standard Crayford myself and had to spend the extra money to buy the 10:1 separately and upgrade it later.)
You'll be interested to hear that our other brother had his superannuation payment come through yesterday, we were on the phone this morning and have ordered for him a 10" dob with 10:1 Crayford ($499), hoping to have it to take out to Ron's place this Saturday night. As a very vague guide, freight to Brisbane from was quoted at $90 for the 10" package.
If we manage to fit both our scopes in next time we come over to the Alice we can all get together and have our own star party, we could call it a "3 dob night"!
Here's my 10" and 12" dobs side by side - the difference doesn't look like much, but it comes into play a bit when moving it. Still, when all else fails, remember the Golden Rule....
I have had my eye on the 10" Super Deluxe for $499 for a while now, with drool at the corner of my mouth and wondering all the time how long I can wait and whether I can use my upcoming tax refund (if I get one) to buy one.
Considering the extras you get with it:
Super Deluxe version includes a right-angle correct image 8 x 50 finderscope, 2" Crayford style microfocuser with 10:1 fine focusing and a 2" to 1.25" adaptor, fan, GSO 6mm, 9mm, 15mm and 25mm 1.25" Plossl eyepieces - and a bonus SP32mm 2" eyepiece, too!
I am just trying not to belt myself over the head repeatedly with a piece of 2X4 for not getting this one in the first place rather than my GEM newt (only 5" too!)
It has the essential fan, 10:1, 2 inch focuser and a bucket load of EP's. Sooner or later you will want to get a nice ED eyepiece to really spice things up (only about $60 or so) and then you will be having to wear a bib to stop the drool from dropping on the primary from having your mouth gape open at the EP.
Go on, you know you want to. Hell, now I want too as well. I'll race ya!
I have had my eye on the 10" Super Deluxe for $499 for a while now, with drool at the corner of my mouth and wondering all the time how long I can wait and whether I can use my upcoming tax refund (if I get one) to buy one.
Considering the extras you get with it:
Super Deluxe version includes a right-angle correct image 8 x 50 finderscope, 2" Crayford style microfocuser with 10:1 fine focusing and a 2" to 1.25" adaptor, fan, GSO 6mm, 9mm, 15mm and 25mm 1.25" Plossl eyepieces - and a bonus SP32mm 2" eyepiece, too!
I am just trying not to belt myself over the head repeatedly with a piece of 2X4 for not getting this one in the first place rather than my GEM newt (only 5" too!)
It has the essential fan, 10:1, 2 inch focuser and a bucket load of EP's. Sooner or later you will want to get a nice ED eyepiece to really spice things up (only about $60 or so) and then you will be having to wear a bib to stop the drool from dropping on the primary from having your mouth gape open at the EP.
Go on, you know you want to. Hell, now I want too as well. I'll race ya!
Chris
Strrrruthh Screwie - those lederhosen will sure come in handy, but you'll still need a bib too: and all I've got to offer you is my older welding apron!
There's so much drool coming off your post me flamin screen is hard to read; our elderly labrador couldn't keep up with you at the moment, not even as he's waiting for his tea: surely you're not telling us that if the supplier offers you a replacement scope, or the money back, your going to forsake another of those little barlowed beauties and find the extra cash difference for a 10" or 12" dob?
Yes, the lederhosen are being recycled as a bib, mmmm, suede bib, I am sure Gunter would approve!
Best Case scenario is they say " ummm, we cant fix it as it has a MAJOR problem, but we can offer you a replacement or a refund!" Then I kick up my heels and trundle down to the shops in my BMW with my Kraftwerk blaring from my Blaupunkt speakers and grab said $499 10 inch dob and giggle like a schoolgirl for at least a few months. Until I have to collimate it!
I am hoping to get it back in a tip top condition as it is quite a good scope, just been too idle without it and looking at what I could have bought for the same money.
Oh well, Oz Lotto's $40 million isnt mine, so I will have to start saving up zie fünfhundert deutschmarks ya?
Gunter agrees Kristoff, but you're not keeping my Kraftwerk cd's after what you said some time ago.....excuse me Kristoff - "what's that Gunter....? No, Kristoff's Telekunken scope is still telefunken, he's hoping to swap it for a dob: I just want my Kraftwerks back before he manages to do something to them!"
Sorry about that screwie, Gunther reckons that he's got no problems with lending you his cordless and wire brush.....
I very recently added a 10" Dob to supliment my Celestron Nextar GT. I went looking at what was available (2 shops I could find on the Gold Coast) and I ended up finding that the price difference between 8 and 10 a couple hundred, but upgrading to 12" was just over double the cost of the 10". I was assured I would not grow out of my 10", and I must say the clarity is every bit as good as I was told. I picked up a brand new 10" Dob for $550. I thought that quite well priced? The 12" was $1200. Seemed a hefty upgrade as opposed to 8-10. The Meade eyepice kit was as much as the Dob though. The wide field peices are a real treat. I thought that better value than the larger mirror. Weight is something too, it's qute a beast to even lug into the backyard, but I find well worth the effort.
I guess my original question is very similar to the old "How long is a piece of string?" question. (The correct answer to which I was taught was - twice the distance from its middle to its end.)
Having weighed the essence of good sense of the replies to my original post and taking all relevant matters into consideration, I've decided to ring up and order a 12" dob bright and early Tuesday morning.
My thanks to all who participated in my time of confusion and soul searching.
As I suspected all along; all other things being equal, aperture does indeed rule!
