Peter
If I were to redesign the ONAG I would turn the guider
focuser into a miniature crayford focuser. The tube is already
long enough to allow for at least 10mm travel and there's plenty
of room inside and in the thickness of the X/Y platform to
allow room for it. Once the general spacing was correct the fine
tuning could be easily achieved. Also would glue a glass corrector
into the focuser tube for better star shapes. It's nice to dream.
Cheers
Stephen
Quote:
Originally Posted by PRejto
Stephan,
I can understand your frustration and I share your feelings about this. But only partially. I've had discussions with Gaston about the "focuser." I think he would be open to any viable suggestion for improvement. You might think a helical focuser is the answer. It certainly tics a lot of the boxes, but, the drawback is the extra back focus it will add to the system. Some scopes/cameras can deal with this while others cannot. The difficulty is in finding something that works easily and doesn't appreciably add back focus. My idea behind my crude rubber band tensioned device is close, I think. A proper design and construction of something like this might be an answer. On the other hand some people don't find the focuser impossible to use as it is. This perhaps depends on the F value of the system and critical focus zone and total amount of energy of the guide star used for focusing with "brighter" obviously easier to deal with. At the end of the day, however, I agree with you that this is the weakest link in an otherwise superbly engineered piece of equipment.
Peter
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