Refiguring a parabolic primary to hyperbolic

Some ATMers on CN are planning to make fast sub-f/4 Newtonians to hyperbolic.

Eg  Chantepierre 8 inch f3.5

he is aiming 203mm f/3.5,  cc -1.32,  fl: 720+/-4mm

Tommm planning on a 8 inch f3.7 with cc -1.305

Same time they are waiting Ed Jones to calculate for them the expected conic constant, ie cc

At first sight, it seems they are using some unknown formula

Later on, it's found they are actually referring to this earlier post:

Hyperbolic primary w baader coma corrector  from Ed Jones

Mike provides a very useful chart to pair with Rosin corrector in this other post

Refiguring a 10 in parabolic newton to hyperbolic 

Davidc135 in this post: 

The primary's hyperboloid figure must provide  to balance the known under-correction of the Baader MPCC III , which will be equal to;

0.81 x (4/f#)^4

So, at f4 the conic of an 8'' primary needs to be around -1.29 to produce 0.81 waves but at f3 the 0.81 becomes 2.56 waves SA and the required conic will now, for the 8'' aperture, be -1.38.

20 in f/3.8

So be aware that, different coma corrector will require different cc , to make a perfect pairing 

Coma correctors compared

Rochi:

- The fun of reverse engineering 

Telescopes-optics