Re: [ATM] Are these kits good? & Refractor Kits

["Richard F.L.R. Snashall" <rflrs@rcn.com>]

Jerry wrote:

>The paragraph on the air-spaced design credits James G. Baker.
>
>Mr. Parker mentions BK7 and F4 so I guess he got the right glass for the
>air-spaced design. So where did all his talk of Max Bray relate to the
>air-spaced design? Did he use the wrong glass for his LA graph of the
>Fraunhofer? Or was that graph really something else entirely, like a single
>element lens?
>
The C and F lines do not cross in the aperture for the air-spaced Newport
design.

On the other hand, ATM 2 (the Wyld article) lists a Dimitroff/Baker design
similar to the Mullett design:

Surf      Radius    Thickness       Glass      Diameter
 STO    Infinity   -0.0860701                         6
   2      52.326       0.6237   BSC517645          6.12
   3     -32.265       0.2799                      6.12
   4     -32.265       0.4455    DF617366          6.12
   5    -145.701     88.81994                      6.12
 IMA   -32.25741                               1.579491

This design has a minimum focus at 550.627 nm and appears to be
corrected for spherical aberration coma at the e-line. It also
has the C and F crossing at the 85% zone (using Bausch and Lomb
glasses).  However, the difference is that this design is visually
better than the Newport prescription, even at the field edge. If
Schott F4 is substituted for the Bausch and Lomb dense flint, there
is some loss, but it still beats the Newport prescription.


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