stefski Posted February 19, 2009 Share Posted February 19, 2009 What's the difference between an astrograph and a telescope? BTW, this is not the first line of a joke! :-)stef Link to comment Share on other sites More sharing options...
Ben Ritchie Posted February 19, 2009 Share Posted February 19, 2009 In theory, at least, an astrograph is a telescope with the sole purpose of astrophotography, typically including wide, distortion-free fields of view for astrometry (i.e. position-finding)The term's been rather diluted to mean a telescope that's well-suited to imaging Link to comment Share on other sites More sharing options...
stefski Posted February 19, 2009 Author Share Posted February 19, 2009 Cheers! :-) Link to comment Share on other sites More sharing options...
Ben Ritchie Posted February 19, 2009 Share Posted February 19, 2009 now what's the real punchline Link to comment Share on other sites More sharing options...
Doc Posted February 19, 2009 Share Posted February 19, 2009 Some astrographs are F2.8 so let in loads of light great for astrophotography. But a PITA to collimate I bet. Link to comment Share on other sites More sharing options...
Ben Ritchie Posted February 19, 2009 Share Posted February 19, 2009 There are a number of designs quicker than f/2.8 - I think Mersenne-Schmidts are around f/1.25 and the Baker-Nunn design is f/0.75, classical Schmidt cameras are faster than f/2 The LSST is a Mersenne-Schmidt design, with an 8m mirror giving a 3.5-degree field of viwe Link to comment Share on other sites More sharing options...
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