GSO Dobsonian - Aperture 250mm / Focal Length 1250mm
... a good priced Dobson with very good diffraction limited optic and enhanced 94% coating

Why should you sacrifice quality only because you want to save money? The GSO EC-line was created to offer Dobsonian telescopes as cheap as possible without reducing the quality of the optics. In our opinion the result is an excellent telescope at an exceptional value for money.

Optical Performance ...
The telescope is equipped with a high quality GSO parabolical primary mirror. We guarantee a diffraction limited performance. As a result you get sharp and contrasty images of the moon and the planets as well as impressive views of countless deep sky nebulae and galaxies. Many details can be seen in these nebulae. The 94% coating offers a brighter image.

High Quality Focuser ...
The GSD doesn't have a cheap rack and pinion focuser, but uses a high quality Crayford focuser. Even at high magnifications focusing is easy and smooth. The focuser is compatible with 2" and 1.25" accessories.

High Mechanical Quality ...
The metal tube is very sturdy. The primary and secondary mirror cells hold the optical elements securely in place. As a result the GSO Dobsonians do not easily lose collimation.

250mm (10") aperture means that thousands of objects are within reach:

Many amateurs say that "real" Deep Sky observing begins with 10" aperture. Many galaxies will reveal their spiral structure. Fine detail in gas nebulae and planetary nebulae will become visible. Globular clusters are no longer just a "blur" or faint light, but instead you will see them dissolved into myriads of individual stars clustered together.

At the same time the GSD 250 is very well suited for observing moon and planets. Under good seeing conditions the telescope will show plentiful detail on Jupiter, will show the division in Saturn's rings as well as the texture of the surface of Mars (e.g. the changing size of the polar caps).

The GSD 250C is still portable:

Despite its huge aperture the telescope can still be handled by one person. The tube is short enough to still fit on the backseats of a normal car.

Image Quality

For best possible image quality you need high quality optics as well as optimized mechanics. The GSO Dobsonian has both. The thin spider vanes (see left image) improve contrast and image sharpness compared with a simpler spider with thick vanes.

Tracking Objects With The GSD 250C

The mount of a Dobsonian telescope is called "Rocker-Box", a fitting name for the uniquely simple and well-working design. The rocker allows you to point the telescope at any point in the sky and allows for comfortable, intuitive movement.

Moving the telescope is very simple, just push the telescope into the right direction – no need to use clamps or motors, it doesn't get more simple than this!

Since you need to move the Dobsonian manually it is particularly important that the movement be as smooth as possible. The GSD has an azimuth teflon bearing for smooth operation. With a little experience 250x is no problem at all.

Advantages of the Crayford focuser in the GSD 250 C:

=> Much smoother focus motion compared with simpler focusers
=> secure and scratch-free grip on the eyepieces through use of a brass compression ring (both 1.25" and 2")
=> no image shift. This means that the object will remain precisely in position while you focus. Simpler focusers tend to be shifted a little bit out of alignment, resulting in a relative movement of the object. This somewhat annoying effect does not occur in the Crayford focuser.
=> no play when you reverse the focusing direction. The focuser will reverse the direction in which it moves instantaneously when you change the direction in which you turn the focus knobs. In rack-and-pinion type focusers there is always a certain amount of play which causes a delay in reversing the direction.