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Old 18-11-2009, 07:31 PM
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Tunnel Vision

AlexN is offline
Join Date: Mar 2008
Location: Brisbane, Australia
Posts: 6,708
Originally Posted by peter_4059 View Post
I thought the MPCC was intended to correct coma in Newtonians rather than be used as a field flattener in a refractor?

"The only Newtonian Coma Corrector that does not change (increase) the focal length of the telescope in any way. f4 Newton optics will remain f/4!"
I'm using a Baader MPCC to flatten the field of my TMB F/6 refractor. I looked at many other options (and spent quite a lot of money testing them...)

I finally decided I did not want any focal reduction (most flatteners are a 0.8x or 0.85x reducer as well) I was told by the previous owner of my refractor that an MPCC would flatten the field provided the distance from the chip to the MPCC was exactly the right distance.... I thought, it can't hurt to try it out... Gave it a go and have been using the MPCC since.. Perfectly flat field without any focal length reduction..
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