Quote:
Originally Posted by Kirkus
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I don't have any experience with an OAG. How exactly do you search out a guide star while keeping the scope trained on what you're photographing? Is the mirror inside the OAG adjustable?
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With great difficulty I'm afraid except for those who have successfully done it, but once mastered is quite "easy"!
- in answer to your question, there is a pick-off prism which (as its name imply) that you use to pick off the guide star that you can target on thru the guide camera
Some other posts recently you can check where the tips were given as to how to achieve success -
http://www.iceinspace.com.au/forum/s...ad.php?t=81343
With regards to the main OTA FL - there is a relationship because if the ratio of difference is too great then you're going to have a hard time getting the guiding results that is good - it used to be when I first started that the figure of 1:3 is about optimum (
http://www.wilmslowastro.com/tips/autoguiding.htm) - eg 2000mm main, 600~800mm would work out fine but like all things these figures are only a guide (not a pun); I've been having success using a 9x50 SW finder scope with my 1900mm OTA - it's good to try-and-see and what works will go towards the knowledge database!
HTH
Cheers
Bill