Re: [APML] Cassegrain notes

[Tonyhallas@aol.com]

Dear Philip,

     Sorry to hog the wires but so many questions! The 14.5" f/8 Cassegrain has the coma of an equivalent Newtonian but slightly more curvature of field and a very slight increase of astigmatism in the corners.When it is collimated properly it can give "almost" perfect 35mm negatives with nothing else. The RC design has less coma in the corners but a lot more curvature of field and from what I hear, is difficult to collimate.
The Classical Cass is a tiny bit more forgiving.If you are going to choose between the two and don't want to use any accessory glass, perhaps the Classical route is a better choice. Kim Zussman helped me a lot with this choice... he checked all this out very carefully before building his... he has a friend named Greg who is a professional optician... much of this info and the baffle design is thanks to his generous help.

     Tony

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