Hi Deimos,
I am the owner of a GS 12" Dobbie from Andrews Communications. I have owned mine for about 16 months. It gets regular use.
The Scope: The scope itself is very good value, and the quality of the optics is suprisingly good for the price. The Tube assembly is remarkably well made with no ill-fitting components. The tube is able to take decent knocks without leaving any marks. The support rings at each end are very solid and prevent the Tube going out of round.
The Altitude bearings, although made of plastic, are very functional and work well. The supplied Crayford Focuser is very good quality and glides like silk. The supplied GS finderscope is a decent size with clear cross-hairs, and a solid, easily interchangeable bracket. The bracket mount is able to take many accessory finders as it has a standard guage dovetail (GS, Orion, Saxon, etc).
The secondary mirror holder (also plastic) is very well designed and simple to adjust. The Spider vanes are fully adjustable in every direction and are nice and thin, and have good mountings.
The Primary Mirror is mounted in a well made Cell with easy adjustment for collimation. Some GS models don't leave much of a gap between the cell and the mirror to help the cooling fan do its job, but the 12" has a larger gap than the others, assisting in taking advantage of the fan to blow cool air onto the mirror back.
The quality of the paint on each scope seems to differ. Many have complained about their GS tubes rusting. Whereas mine gets wet (and iced up) on almost every occasion and yet it has no rust anywhere.
The tension springs work well, but I have found them easier to use (and to prevent busted knuckles) by turning them upside down.
The Rocker box is reasonable quality but can suffer from moisture. It is made of chipboard but does have a good quality finish to it, and is easily assembled. The Azimuth Bearings work smoothly, but often the centre bolt can be a hassle until adjusted correctly.
Weight-wise the 12" can be a fairly heavy beast depending on how far you have to carry it. I find mine OK to carry around, but many people use a trolley to make the job even easier.
The fan is a great addition as it assists in faster cooling of the mirror. I also use mine when the mirrors start to fog. The air circulating blows the dew out of the tube.
There are many alterations that can be done to improve the action and ease of use of these GS scopes, and they are covered in many places in this site.
Observing: On first impression you cannot help going 'WOW!'
The extra light gathered by the 12" is amazing after using smaller scopes. At low power, Galaxies seem to jump into the eyepiece (at a dark site).
Nebulas are clearly seen and Orion Nebula shows Green & Pink colour. Wide-angle starfields seem to go on forever resloving faint stars not normally in the FOV of smaller scopes.
At higher powers the 12" shows great detail in almost all objects.
Mounting: it is also possible to mount the 12" onto other mounts but this can be a very expensive exercise if you cannot build your own EQ or fork mount. The expense is due to the shear weight and size of the 12". It is heavy for an EQ mount, plus add the weight needed in the counterweights and it certainly adds up. I was fortunate to be given an old EQ mount built to carry up to a 16" scope. I restored the mount and added motors. I notice you say you are building a mount. Make sure you over-build it!
Another alternative is a tracking platform.
Transport: Definately something to think about when considering a solid tube telescope of this size. Many cars cannot accomodate the size of the 12" if you intend to have passengers. There are ways to get it to fit into most cars, but it can be a very tight squeeze. Mine fits into my Ford sedan but I cannot fit a passenger when I do. The tube just fits across the back seat and the base on the front seat, or alternatively I lay the front seat down and lay it front to back and place the base on the other side of the back seat. Again- no passengers!
On Delivery: When mine arrived at my door it was very well packed with 2 solid cardboard boxes and Styrofoam inserts to prevent damage. When unpacked there was no damage to any parts.
Overall: I am personally very pleased with my GS 12" Deluxe Dobbie. I enjoy the large light gathering capacity, the smoothness of the Crayford Focuser, the quality of the overall product and the ease of collimation.
It is not a research grade instrument, but for the price it exceeds expectations.
I hope this has helped.
Below: These pics show the bulk of the 12"
Pic 1. The size of the 12" on its Dob mount.
Pic 2. The size of it up on a large EQ mount. (my daughter is 5'4" tall for comparison)
