Celestron is offering a 3" f/4 Newtonian telescope for around $50 to celebrate the International Year of Astronomy. The combination of low cost and low f/ratio make it well suited to a small, portable occultation recording station. This is a report of some simple tests using this 'scope with a slightly modified PC164C-EX2 video camera.
This telescope offers the following advantages over a similarly sized 80mm f/5 refractor:
- Lower cost
- Includes simple but effective mount
- Newtonian design is more dew resistant
- Works as-is with video camera, but camera must be slightly modified
- Reaches roughly mag 10 under decent skies with PC164C-EX2
- Dobsonian mount is well suited to pre-pointing
View of telescope with included mount and video camera in place. In order to reach focus, the camera must be inserted into the 1.25" focuser tube, which means filing down the diameter of the camera slightly. This makes it convenient to use with other telescopes anyway. Alternatively the focuser could be replaced or modified to allow the camera to reach infinity focus.
Front view of 'scope, showing simple diagonal mirror on mounting
PC164C-EX2 with diameter filed down slightly. I used a rotary sander, but a lathe would be better. Only a small amount of material must be removed to make it fit into a 1.25" tube.
View of m13 and field stars. This is the view from MetaGuide with live integration of 20 frames. This approximates what the eye can detect in the live video, and reaches roughly mag 10. There are several hot spots that should be ignored.
Vega and nearby stars, as above.
View of Mizar and Alcor, plus field stars, as above.
Occultation and Video Timing Projects
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