Quote:
Originally Posted by multiweb
The hyperstar will give you F/1.8 at a fraction of the price.
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Sure, but it is still a full f stop slower and only images 15% of the area of sky (approximately).
Interestingly, the places where I have seen the hyperstar specs published, they don't state performance in terms of theoretical ray trace results (which aren't always meaningful) or real world encircled energy.
Anyway, aside from all that the design is really impressive.
Achieving 7 degrees of anastigmatic flat field in a non-symetrical compact cassegrain using an aluminised spot on a correcting element as the secondary mirror and keeping it all spherical... Now that is genius.