[ATM] Another Reuse

[Richard F.L.R. Snashall]

There always seems to be a desire to be able to make
one telescope and, later, enhance it with some upgrade.
This is another example of that reuse.

A 152.4 mm f/12.8 [green] aplanatic doublet:

    http://users.rcn.com/rflrs/Ptz11-63b.atm   ATMOS input file
    http://users.rcn.com/rflrs/Ptz11-63b.len   OSLO input file
    http://users.rcn.com/rflrs/Ptz11-63b.txt   TEXT prescription
    http://users.rcn.com/rflrs/Ptz11-63b.zmx   ZEMAX input file

Modifying the spacing and adding a secondary doublet,
one gets a 152.4 mm f/9.65 [green] anastigmatic Petzval:

    http://users.rcn.com/rflrs/Ptz11-63x.atm   ATMOS input file
    http://users.rcn.com/rflrs/Ptz11-63x.len   OSLO input file
    http://users.rcn.com/rflrs/Ptz11-63x.txt   TEXT prescription
    http://users.rcn.com/rflrs/Ptz11-63x.zmx   ZEMAX input file

The unique feature here is that the modification actually
reduces the air-space of the primary doublet to zero.  The
bonus here is that there is very little change in the F-C
longitudinal crossover zone -- from less than 85% for the
doublet to greater than 82% for the Petzval.