Questions about GSO 12' dob

[Darth Wader]

Well I've got the fever and looking to upsize my rig very soon. I've got my eye on a solid tube GSO 12" dob. Read a few reviews online and they were all positive but I have a few questions for any members with one of these scopes.

Does the primary mirror have a centre spot for collimation?

How well does it hold collimation?

What is the length of the OTA? Height/diameter of the base?

I know they are impressive on DSO's, but what are views of the planets like in good seeing?

This may be a stupid question but would it be easy to attach a larger finderscope to the OTA, or will this upset the balance too much?

Apologies for all the questions, I want to be 100% sure about this scope before I drop the cash on it. Also very interested to hear your thoughts or criticisms on this particular scope.

Cheers
Wade

[Tandum]

I had one for a while. It gave stunning views but it was really heavy. I had to get one of those cheap fridge trollies to move it around. There is a center spot on the mirror however when I pulled the mirror out of this 10" I found the spot was not in the center of the mirror. I'd stick a laser in it evertime I used it and it probably needed adjusting every 3rd or 4th use but I never traveled with it, it didn't fit in the car easily :(

[mswhin63]

I have a 12" collapsible and after using it for a while realise for travelling and home use it is excellent. There would be no way now I would recommend a solid tube if you intend to transport it to observing locations.

I would only recommend 12" if it does not get transported.

[big_dav_2001]

Hi Wade...

Ive currently got a 12" GSO Dob, and LOVE it!!!



Mine does, however, i bought mine 2nd hand, so it may have been added by the previous owner.



In short, VERY well!!!... I bought it from a woman in Canberra, and after sitting it in the back of the ute for the 3 hour drive home, it was still alligned... I have only had to collimate it a few times since... (Most advise collimating every time it's moved, but it seems to stay in collimation, and i think if it aint broke, dont fix it...:thumbsup:)



Fully assembled, it stands approx 5.5 feet tall, the OTA alone would be approx 5 feet long...the base (without the OTA) stands about 1.5-2 feettall, and would be approx 2 feet in diameter...(very rough measurements..cant find the measuring tape...:mad2:)



They are VERY impressive with DSO's, as for planets, ive been able to faintly view the EQ bands on Jupiter, and with the help of barlows ive seen some very faint surface detail on mars. Saturn is always impressive...:eyepop:



Most of the GSO dobs come with a 8x50 right-angled finder, but i highly reccomend that if you purchase a dob, your next pruchase should be a Telrad finder, when used along with star maps, they are an invaluable tool and make star-hopping to the faint fuzzys a breeze...:thumbsup:... Along with the heavy EP's, Telrad and standard finder, there is a fair bit of weight to the top of the scope, but the weight of the primary mirror offsets it pretty well, and ive had no problems with balance...

Some things i would advise if and when you purchase it though; you might want to add some locking castor wheels to the base, it makes moving and transporting a lot easier; the azimuth axis can be a little 'sticky' at times, so consider adding extra teflon pads to the base to make the movement smoother; also adding a set of bobs knobs (http://www.bobsknobs.com/) makes collimating a lot easier (not that ive had to do it often anyway)...

All in all, it is a GREAT scope, and i'd be happy to reccommend it to you or anyone else who is looking to upgrade...

Hope it helps
Davin
:cheers:

[big_dav_2001]

GOOD POINT!!!!!..... If you're going to get one, i hope you've got a ute or station-wagon, thats the only way you'll get to move it anywhere...

[mswhin63]

I have a station wagon an still would not want to transport a solid tube :)

[batema]

Hi Wade,

I'll have a crack at this topic. Our school bought the GSO 12 Dob and my teaching mate took it home first on a fRIDAY NIGHT AS I had to go out I think. I phoned him and when I got home his excitement caused me to drive 20 minutes to have a look. In one hour we found about 15 galaxies and could not stop laughing at NGC 253 as the view was out of control like I'd never seen before. Stunning. There are a lot of good point made. I'm 46 average fitness and I can lift it and put it on the base but it is a bit heavy. I have a Nissan Navara 4x4 and the thing doesn't fit into the ute section so I take the Subaru forester with the back seat down. I do collimate ever time I use it only because I'm ust to doing it and it takes no time. It does have a circle on the mirror and the planets with a powermate are great. We've even had rings made for it and chuck it on an EQ6 Pro bot that is absolutely pushing the limits. I do love this scope but also I have looked through a 10"DOB and they are fantastic as well.

Mark

[Darth Wader]

I've got a Commodore... hoping I might be able to fit the OTA across the back seat and the stand up front...:shrug:

[barx1963]

Wade
I bought a 12" GSO dob in July last year and love it. Although a solid tube is a bit of a handful a simple $50 trolley and a bit of carpentry will make it much easier to move around. See http://www.iceinspace.com.au/forum/showthread.php?t=47433
Also I have made a couple of straps from Webbing and velcro that make it much easier to carry.
To your specific queries,yes they have a centre spot.
Mine holds collimation fairly well but I have replaced the springs with ones from a Bobs Knobs kit. As I have to wheel it down a couple of steps i always recollimate before observing, get a laser collimator, makes life really simple . Also definately get Bobs Knobs. Worth every penny!
The OTA is 1500 mm long, the base is 630mm diameter and 690mm high.
I use it a bit for planet, but that is not its strength. Jupiter is fairly good and Saturn OK, need perfect cosnditions and the right time of year to see much on Mars. The best thing about it with planets is picking up small satellites, I have seen Enceladus in mine!
The finderscope on mine is pretty good, does an OK job. Wouldn't spend money on another. Mine came with a 32mm plosll which acts as an intermediate finder when I need it between the 8x50 and my 24mm Pan.
I have found that if you load up the end of the scope too much (I have a telrad, a laser finder, big EPs, dew straps ) you have to tighten the tension controls fairly tight which makes the alt action a bit 'jumpy', Am about to attached some weights (magnets ) to the mirror end to try and smooth it out. The tension control system in these GSOs is a thing of beauty IMHO.
The Az motion can be very loose. When I first set it up I found if a gave it a push, it spun about 3-4 times. A coupla bits of felt slows it down a tad.
Alround excellent value for money as they can be picked up under $1k IMHO
Malcolm

[Darth Wader]

Thanks for your input guys, really helpful!:thumbsup:

Just measured the family chariot and I think I'll have to settle for the 10" version... at least until I can pony up the dosh for the 16" truss dob I have just seen on the Andrews website, it's a corker!

Cheers
Wade

[barx1963]

A GSO 10" is still a fine scope. Good luck with it!

[wavelandscott]

As they say in the wood building business, measure twice and cut once!

If you can chart your course forward with care...a 10 inch is a nice size scope that can do a good job as an all-rounder...I still get out the 8 inch for quick look sees...

Having said that, if you seriously do have the "aperture fever" I might suggest saving your pennies and just waiting to buy the truss. Buying the tube 10 incher and then re-selling to fund the 16 incher might not make as much finanical sense as waiting.

The 16 inchers (even truss) can still be a load and I'd strongly encourage you to see one in person (assembled and un-assembled) before buying one. The base can still be pretty big on some of the mass produced ones...

[Darth Wader]

True, but the 16" is a looooooooong way off yet! :lol:

[ausastronomer]

I would be giving a lot of thought to getting a 10" Meade Lightbridge which is a truss tube version, of the 10" GSO solid tube. It is made by GSO and uses the same fittings and optics as the solid tube scope. It is infinitely easier to transport and store than the 10" solid tube version, which is not small and no lightweight. I have a 10"/F5 solid tube GSO which is an excellent telescope optically, but a pain in the A to store and transport. Once my 10"/F5.3 truss scope is completed I will be selling the solid tube scope and never again will I ever own a solid tube dobsonian. The truss design has so many advantages over the solid tube design it isn't funny. No tube currents, better primary cooling, smaller secondary mirror etc etc and that doesn't take account of the storage and transport advantages of the truss scope. A no brainer IMO. Even if you have to wait a short period to save some extra dollars to get the truss version, that's what I would be doing.

Cheers,
John B

[Steffen]

Hi John, excuse my ignorance, but why does the truss design have a smaller secondary mirror? Or were you comparing the Lightbridge vs solid tube 10" specifically?

Cheers
Steffen.

[ausastronomer]

Hi Steffen,

I was referring to the generic advantages of the truss design over the solid tube design and why I personally will never go back to the solid tube design.

Because tube currents are not an issue with the truss design, it is possible to use a smaller diameter Upper Cage Assembly (UCA) than the tube diameter of a solid tube scope. For instance a 10" solid tube dob will use a 12" to 13" diameter tube. A 10" truss dob can use an UCA which is 10.75" in diameter. This brings the focal point inwards by a minimum of .62" in this case. This enables you to use a smaller secondary mirror, which improves contrast and planetary performance.

The 10" Lightbridge has the same sized secondary as the 10" GSO solid tube, so in this particular case it doesn't make a difference.

Cheers,
John B

[erick]

Thanks John, I was scratching my head as well. So the additional change is a slightly longer distance between primary and secondary mirrors in the truss over the solid tube. Eyepiece height slightly higher above the primary? (Obviously for the same focal length primary.)

[Waxing_Gibbous]

Late as usual.
I had the 12" GSO for a while and found it a real handful, especially on windy nights. Speccy views when it was calm though. I would definately reccommend a collapsible design for anything over 8". Much easier to transport if only from your garage to the garden.

[Steffen]

Thanks John, that makes sense. So, essentially, solid tube Dobs should really use conical tubes rather than cylindrical ones? I suppose they don't because those would be harder and more expensive to make…

Cheers
Steffen.