Optical Tube Assembly: Telescope GSO Newtonian GSN 1509 CR OTA

Aperture 150mm / Focal Length 900mm / f/6

This Newtonian is a truly all-purpose telescope for every amateur astronomer. Next to its outstanding visual performance it is also perfectly suited for astro-imaging. The Newtonian is made exclusively for Teleskop-Service according to our specifications.

Special Feature: The 2" Focuser

Most instruments of this size have 1.25" focusers only. This is OK for visual use, but limits photographical capabilitie. The GSO Newtonian has a 2" Crayford focuser and sufficient back focus to be able to reach focus with DSLR cameras. With the supplied 2" extension tube you will also reach focus with regular eyepieces.

Image Quality

This GSO Newtonian of course has a parabolic primary mirror for optimum performance. GSO has a reputation for making some of the finest mirrors in this price range. We guarantee diffraction limited performance, but in our experience the GSO telescopes are even much better than that. One particular advantage is the very smooth mirror surface that results in practically no light scatter.

Moon and planets can be viewed even at 300ith very good sharpness and contrast. Tiny details in the moon's craters become visible. You can see Saturn's Cassini division, belt details in Jupiter's atmosphere, ...

With 150mm aperture a huge number of gas nebulae, star clusters and galaxies are within reach. Some galaxies even begin to unveil their spiral structure!

2" Crayford Focuser

Almost unique for a Newtonian in this price range and size the GSO 150/750 CR comes equipped with a 2" Crayford focuser. This focuser has several important advantages:

-- The Crayford design offers a very smooth focus motion. The focuser is also free from image shift, which is particularly important for photography.

-- You can use 2" eyepieces and will then be able to view larger fields of view than are possible with 1.25" eyepieces. Of course a 1.25" adaptor is included, so you can also use 1.25" eyepieces.

-- Optimum photographical results can only be achieved when using a coma corrector. However coma correctors are usually only available in 2" size, so you can't use them on telescopes with a 1.25" focuser.

Focal Position / Back Focus
This telescope is made with astro-imaging in mind. SLR and DSLR cameras require a large back focus, so the focal plane was intentionally moved further from the tube.