Quote:
Originally Posted by multiweb
In the new celestron HD range I believe the primary and secondary are still spherical so there is an ideal spacing which is the same as a stock SCT. The corrector lenses inside the baffle tube give a flat field. I'm pretty sure the hyperstar is the same unless it has changed again. I was told it was at the time by starizona. The Meade ACF secondary is not spherical to correct for abberations.
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Hi Mark,
You need a spacer for the standard Hyperstar 3 to work with the EdgeHD or you need to purchase the newer EdgeHD Hyperstar assembly. Yes the mirrors are the same design from the old Celestron SCT and EdgeHD, there are slight differences between the two, including, but not limited to the rear cell housing the mirror. This results in the hyperstar needing to be set a little further forward (away from the corrector) to reach focus.
Here is the link to the adaptor.
http://starizona.com/acb/HyperStar-E...P3112C773.aspx the newer Hyperstar come in 2 versions. EdgeHD and standard SCT.
As for the Meade ACF - you are correct. However it only corrects for coma and is not a true astrograph; and this is where the the EdgeHD is different. This became evident during beta testing and to us optical designers.
cheers
Terry