150mm f5 Newton

SLR Lenses

150mm F5 Newton

This is a basic, and smallish, 150mm F5 Newton made by GSO, my first telescope.

I've made some modifications to it:
-an electric focuser
-improved back-focus capability to allow use of focal reducers and filter wheels
-cooling fan for primary mirror
-central mark for primary mirror to help collimating

This is an electric focuser modification made from 2 gears and an old modified R/C servo. This can be powered by other modified R/C servo (turning othercauses the other to turn also) or by a separate hand-controller powered from 12V. Electric focuser makes focusing much easier, especially with CCDs, since it does not cause vibrations on optical system that would have to attenuate before focusing can be verified and then re-adjusted..

This picture also shows the T-thread for mounting the Artemis CCD camera at prime focus. Bringing this mounting thread so close to the neck of the focuser tube the will probably allow the use of a focal reducer and/or a filter wheel.

 

This is a cooling fan for primary mirror. It keeps the mirror temperature closer to ambient during observing to avoid turbulent tube currents with temperature differences that will degrade the image on high magnification visual and CCD use. It also shortens the required cooling time befiore using the scope when it is brought from the house to outdoors.