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Cant get picky with S/H RCs in OZ Jase, they dont come up very often. I couldnt resist, it could take a year for a new one (well, 1-2mth for an ion milled model, but thats another US$6k just for that). Its reliability and thermal stability Im after, RCOS is hard to beat.
Ill use the AP 0.67 reducer I have, this will give a sweet 1.23 arcs/pix at f6, or, apparently I could space it out to f5, wider will hopefully mean I can use internal guiding without a rotator. The dichromatic splitter youve mentioned before is might attractive but pricey, I might fit an OAG to avoid guiding through filters. Id really like to use external guiding, but I have been told repeatedly differential flexure is unsolvable for exposures longer than 10min, I still dont believe it, Im going to try locking down hard (no rings etc) the guide scope, focuser and cam and see what happens.
BTW, why do you say changing the primary/secondary spacing be such a problem?, the ST8 is small format, no vignetting. I was hopeing to possibly do just that to go to f5?.
Cheers
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