dobsonian

[nicnac]

i am thinking.......BIGGER!

im going to look at dobs as i aint into anything other than having a gander.

so,

8" or 10"

truss or not?

skywatcher or lightbridge?

or should i not be greedy and stick with what i have

all opinions welcome

[John]

It seems you have aperture fever !

I've owned up to 12" dobs.

Personally, I found 10" more useable / moveable although if you can handle a 12", the views are superb !.

Up to 10" I'd stick with a solid tube - the truss design does not seem to deliver advantages until 12" or above, IMHO.

Be greedy ! - get aperture ! - it brings the universe alive (theres a couple of glasses of decent Californian white talking there !).

[nicnac]

skyliner 250 then

how tall does that stand John, i have limited space (pantry)

[BenM]

They're all basically the same spec, around 1200mm focal length, 1/4 wave parabolic mirrors, 2 inch crayford focusers, rolled sheet metal tube and a melamine laminated particle board AZ base.

Truss and collapsible tube models solve portability problems if you don't have a big enough car or pickup truck but otherwise I think they'd be more likely to need collimation after moving. If you'll not move it around much, then it doesn't make much difference but you'll want to shroud a truss tube for dust and stray light.

I think everything you're considering, they all use solid mirror blanks so cool down time and weight are roughly the same per aperture. Cooling fans help speed things up. Zhumell offers the fan as part of the cost, with others it can cost more. Zhumell (GSO) appears to be offering the best value all the way around unless you want truss, collapsible, or intelligent options (meade, skywatcher, orion).

For a nicer scope, I would use a mount like this one: Dobsonian Mount

I'd also look at getting better mirrors and I'd go with curved spider vanes because I don't want to see diffraction spikes. But it depends on your budget and goals. For me there's a real limit to how much aperture I'm willing to go for so I would try to get a better quality 10 rather than a 14 or 16 or something.

Consider whether you'll want to use an observing chair, stand, sit or what. 10" (at 1200mm) seems to be around ideal for most people. Once you go 12" or over, the eyepiece height can be less compatible unless you're taller.

A telrad is a good accessory for these.

Also, I think eyepieces are critical with fast scopes. A big dob is where you spend more on eyepieces than you do on the scope. If your collection now is just some cheap plossls, consider that. You might also want a Parracor depending on how tolerant of coma you are.

My personal preference is for the Orion 10" non-intelligent but I'd add eyepieces, parracor, mount, and a few other goodies and it would run around 1500 pounds when I was done. I nearly went that way but I decided I couldn't work with the eyepiece height of a Newtonian or the weight. I want small children to look in my scope without standing on a chair or ladder and I'd like to be able to toss it in a billingham and go down the road.

While I appreciate the simplicity of the newtonian reflector, it might very well be my favorite optical design, I think there's something particularly fascinating about John Dobson's original concept of a sidewalk telescope, He was not the first sidewalk telescoper by any stretch of the imagination but he presents on the sidewalk with a *home-made* telescope. It completely takes the commerical, consumer product aspect out of the way of the non-astronmer. Now they're looking at the heavens rather than another Chinese product for western consumers to toss their disposable income into. They wonder at Jupiter in the sky rather than how much it cost you, because if they ask, you can explain that you made it with a cardboard tube and a gallon glass jug. They walk away wondering about the heavens instead of wondering how they can afford one for themselves and what their credit card balance is.

Anyway, best wishes

[perrin6]

A 12 inch dob was for a long time my ideal scope, even before I ever owned one, and it still is. A look through one at M51 the Whirlpool galaxy, M82, saturn, jupe and the M13 globular and I feel I'm home ! I'd want as long an F ratio as poss. though, to maximise planetary views.

[nightfisher]

since you have a 150 tal i would suggest getting the 10 inch dob

[nicnac]

Thanks chaps

[Moonshane]

I'd try and see and even better see through a 12" before you buy anything. if you can handle it and fit it where you want it to go then it's a real step up. The 10" would also be excellent but I went for the 12" as I knew I'd always be wondering..........

[nicnac]

thinking on it, i may just get a dob base for the TAL....until i have buttered the ole lady up enough that i can spring for a 250 or 300 without getting my head removed.

[Moonshane]

if you want the convenience of an alt-az mount with the Tal, maybe point the CG5 straight up. this converts it from GEM to alt-az mode and (for me anyway) makes it more intuitive.

[DrNeb]

ello ello.

check out my first thread here, it was deciding to go for either a 200p or 250px.

http://stargazerslounge.com/equipment-help/117811-first-scope-skywatcher-200p-250px.html#post1566334

i went for the 250px in the end. Cgolder, a experienced member of SGL posted some comparison pics on that thread, it might give you a good understanding of proportion. 10 for me is manageable, but it is NOT a grab and go scope.

However, LOVE IT. best purchase in the last 5 years easily!

[Chris H]

For me my 10" Dob is a grab and go scope, it lives in my garden shed so it's always ready cooled and I often pop out for 30 mins or so. Very useful for a quick look at Saturn in the am.

The 250 stands 138cm high and is 58cm wide at it's widest point it's an Orion (USA) XT10i so the Skyliner 250p will be pretty similar.

[callisto]

My 10" Dob goes everywhere with me,

Fits perfectly in my little Fiesta,

And IMHO the perfect aperture size

[DrNeb]

By grab and go, i'm not refering to keeping it outside. to get the most of it i need to take it to a dark site. i struggle getting all my kit in my ford focus with another passenger. your Fiesta must be like a tardis! lol

if you have great views outside your house then yes, grab and go.

[jonstarrysky]

agreed, 10" dob hits a sweet spot, practicalities vs. light gathering power. I use the XT10i as well.

Fits in a car sideways which is handy. For 12" I'd go truss....So much more choice these days with goto & tracking on dobs etc. Also bigger sizes becoming more available other than just the 16" Lightbridge eg XX14i.

[twotter]

Threads like this give me aperture fever

[brantuk]

If you're gonna get a dob then you might as well get the biggest aperture in budget imho. Skywatchers are great vfm in both the solid tube and truss tube - get the 10" if you have a choice. Budget in a couple of decent quality 2" ep's for those lovely wide field views of galaxies, nebulas, and clusters

[swamp thing]

Hi Nick

First off i would be greedy its in my nature.

I would go for a 10" over an 8" any day. In those sizes you'll want a solid tube too. No point fiddling around with trusses in that size scope.

10" is as has been said a great grab n go scope.

As brantuk said you'll definitely wanna budget for a couple of 2" eyepieces. make em gooduns too. Gotta have good eyepieces in short f/ratio scopes.

regards Steve

[nicnac]

cheers chaps

[ollypenrice]

If floor space rather than height is the stor

[ollypenrice]

If floor space rather than height is the issue, as it usually is, the bigger one is not much bigger. But visually there is quite a difference...

Olly

[AWR]

The 12" SW Dob sits on a 65cm circular base and is 160cm high when upright.

HTH

Andrew

[nicnac]

im about 176 (ish), well, unless i have shrunk since 1999, so that sounds a good.