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Old 22-11-2013, 02:43 PM
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Satchmo (Mark)
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Satchmo is offline
Join Date: Dec 2005
Location: Sydney
Posts: 1,858
Originally Posted by alpal View Post
You can clearly see that the spot size for a Newt. is much greater than an RC.
(The SCT is shocking.)
I wish I could find a higher resolution image of this graph of optical results.
Its a classic example of reviewers/companies abusing peoples lack of knowledge about spot diagrams or optical designs to further their own causes.

If you would like to see what a large Newt can do with a 3" Phillip Keller Corrector on a Newt ( seeing and all other issues aside ) have a look at these spot diagrams of a 400mm F3.5 with 3" corrector to the edge of a 45mm diameter circle.

The square box is 20 micron in diameter . As these spots are just larger than the airy disc at that F ratio I think it is valid to look at spot diagrams, but seeing will of course bloat the discs larger .
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