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WINTER STAR PARTY 2009

The Crew: Me, Roger Ceragioli, Mark Beale and Vince Garland. We had a great time. A week in the Keys after a winter up north, or anywhere, is an immensely refreshing experience. Of course, there was the observing, the wonderful skies, seeing Orion hanging high above; but there is mostly the comradierie and the good times - and that $42 quart of Jack Daniels that slowly vanished one evening.

 

The 12.5" D-K was purchased by Mark Beale and brought to WSP, AP 1200 mount and all. Last year he had the 10" and this year the 12.5". 

 

Checking collimation. The telescope was driven 1,500 miles all the way from New Jersey by Mark. It was collimated prior to when it left (in fact, it was collimated when I delivered it) and never required adjustment the whole time we were there.

 

 

Back end, showing collimation and locking screws, slewing handles, finder and general arrangement. The collimations screws are 1/2" x 24 pitch thread and are compressed against the tip-tilt plate with Belleville disk springs. These springs suppress any possible lateral movement and result in collimation that stays put.

 

The curved vane spider allowed for those refractor-like views. Note the small 24% obstruction. By keeping the secondary small and light a simple and elegant curved vane spider arrangement can be constructed. This spider completely eliminates spikes. Yes, the diffraction is still generated and is smeared more or less evenly around the field of view, but when one takes into consideration typical design and fabrication errors this spider actually produces less diffraction than a Maksutov corrector!  And please note the absence of a metal hood. With a D-K or even a classical Cassegrain used for visual or non-deep sky CCD work a hood merely exaggerates the size of the secondary by artificially extending the diameter of the secondary outward, something that hood users seem to want to ignore. All that is really needed is a baffle tube that is properly designed and possesses the proper light suppressing qualities to stop any grazing reflections from entering the eyepiece. The suppression of ambient skylight is a complex issue and one solution does not suit all Cassegrain type applications. For planetary and double star work it is most important to have a small and cleanly defined obstruction and an efficient baffle tube.

 

More Information

Initial Delivery and Observing Report  

The Future

My goal over 2008 was to fully develop a 12.5" Dall-Kirkham tube assembly. That was accomplished and the remainder of 2009 will be absorbed in finishing the initial run as well as developing other new products. These are projected to include another run of 10" D-Ks, continued work on the glass liquid apochromat and the likely production of an 11" astrograph - details of which will be released over the next few months. I'm looking forward to next year's WSP to demonstrate some of these new things. I need an excuse to get to the Keys in mid winter.

More to follow as things progress ...

 
Me at 18