Baader Planetarium offered me the opportunity to test the first Planewave CDK17 (aperture 430 mm) in Europe.
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Design:
The OTA is fixed to the mount by a very sturdy dovetail adapter. The mirror cover is perfectly sealing the mirror box to avoid dust and spider deposits on the main mirror. |
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As camera my STL-11000M was used together with the large 8-pos filter wheel. The total weight of the OTA with the imaging train is at 106 lbs (48 kg) The image scale for the STL-11k is 0.63 arc sec per pixel, the field covers 41.5' x 27.7'
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Here you see the view from the secondary focus into the OTA. The light ring around the black baffling tube is indicating that the secondary mirror is oversized compared to the diameter of the baffling. This helps to reduce effectively possible reflections from stars close to the border of the field.
Improvements can be done at the holder of the secondary that is equipped with just 4 push screws. A design as for the CDK 20 using 3 push-pull screws would be preferable. |
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A star test was performed, however at bad seeing. Here you find a video showing a bright focused star at f/20 with a b/w webcam. |
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Here you find a video showing a sequence from extrafocal to intrafocal position at f/20 with a b/w webcam. |
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The autoguiding was showing rms deviations of typical 0.4-0.5 arc sec, this was caused by the home made light weight pier that was not as stable as it should be.
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After all information - what counts is the imaging performance. The not too slow system with generous aperture is producing amazingly detailed images at rather short exposures. The stars are of pinpoint shape out to the corners of the 24x36 mm CCD field.
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Here you see a straight LRGB on NGC206 within the Andromeda galaxy using in total 100 min exposure time (new Baader LRGB filters).
Same as the previous image this one is completely uncropped. I could not see a significant focus drift for 2-3 h of imaging time at falling temperature. |
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