I came across an old 70mm refractor that we were using 13 years ago as a guide scope. It is a cheap Meade RB-70. The specifications are on a label on the focuser housing.
Click on any image to get a closer view.
The scope being used as a guide scope in November 2010
These scopes are no longer available. the RB series having been recently discontinued, and superseded by the Meade Infinity 70mm refractor which has similar specifications but a more robust AZ mount. Being an f/10, 70mm refractor, the colour correction of the air-spaced doublet achromat lens is acceptable. The large dew shield works well preventing the formation of condensation on the objective.
The scope was cleaned and even after a long time of disuse, it was a simple matter to clean all surfaces of the doublet objective and replace the elements in the lens cell.
Tube rings had originally been fitted when the scope was used as a guide scope. Now they were attached to a dovetail bar for attachment to a mount and a Skywatcher finder shoe was fitted to hold a small guide scope in place in case the scope is tested for deep sky imaging.
The test involved imaging the 65.3% waxing Moon.
The scope was mounted on a Celestron AVX mount and a Player One Mars-C II camera, fitted with an IR/UV cute filter was placed in a higher quality diagonal than the one that came with the scope.
The imaging equipment
AstroDMx Capture was used to capture 1200-frame SER files of four overlapping areas of the Moon
The best 85% of the frames in each of the SER files were stacked in Autostakkert!
The resulting four files were stitched into a 4-pane mosaic in Microsoft ICE
The image was then post processed in the Gimp 2.10 and reorientated to produce the final image
65.3% waxing Moon
The Meade RB-70 functioned well as a lunar imaging telescope.
When time permits, the scope will be tested with other cameras with different sensor sizes and on some deep sky objects
