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Old 01-05-2012, 02:46 AM
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Peter Ward
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Peter Ward is offline
 
Join Date: Dec 2007
Location: The Shire
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Quote:
Originally Posted by bratislav View Post
There is no need to simulate 1/2 wave of spherical, as all modern raytrace programs will be able to easily show the results of 50% of obstruction....
Guys...just so we are clear about the point I'm making....

An otherwise perfect optic with a 50% central obstruction does not degrade a telescope's resulting images in the same manner as a 1/2 wave spherical error....or turned edge or...or astigmatism etc. etc.... i.e the sort of errors you may find in an optic built to a price, rather than spec.

(download Aberrator...it's free...& play with the values )

One is a frequency domain filter (eg central obstruction), the other is a focus error.....which really will bugger up images, al la Hubble before it was fixed.
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