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Old 07-11-2009, 07:19 PM
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mtodman (Matt)
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Join Date: Oct 2007
Location: Arcadia, NSW, Australia
Posts: 189
Hi Allan,
Imaging on a fork mounted SCT is indeed doable. Some people have managed some very fine results. Having said that, it's a lot of hard & frustrating work to get everything working well. I managed to get results with my 10" LX200GPS that I was reasonably happy with but there were many frustrating nights to get to that point. It the reason I have decided to change over to a GEM setup.
The list below is what steps I took to improve imaging (obvoiusly some of it doesn't apply to your C11).
  • Get a good polar wedge. I made my own which works very well. Needs to be very solid & have fine adjustments.
  • I replaced the standard plastic drive gears with stainless steel gears “Bucks Gears”.
  • Install a guide scope (ED80 with Meade LPI) piggybacked on main OTA using Orion tube rings.
  • Upgrade from Orion tube rings to home made piggyback system.
  • Train PEC using Andrew Johansen’s PEC utility.
  • Train PEC using Pempro.
  • Upgrade guide camera from Meade LPI to Meade DSI Pro II.
  • Balance setup with weight bias on the Eastern fork arm.
  • Use Bahtinov mask for focusing guidescope.
  • Achieve very precise polar alignment. This made a big difference as it meant that I could dissable DEC guiding and inly guide in RA.
As Gary said, I wouldn't bother with a field derotator. The main issue is that it relies on very accurate tracking in both Alt & Az so unless you have a very accurate mount with very little periodic error, you may be fighting a losing battle.
Definately get yourself a wedge. If you can't afford to get a solid one with fine adjustments, then at least try something that you can afford.
A DSI III should give you some pretty good results, especially is you use a Focal Reducer. I used a Meade F/6.3 reducer with my DSLR. You may even be able to go to a, F/3.3 with the small chip size of the DSI III. The short Focal Length would make tracking easier.

The main thing is to give it a go and see what you can achieve.

Cheers

Matt
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