Re: [ATM] N-KZFS-4

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

Richard F.L.R. Snashall wrote:

>
>
>Surf      Radius  Thickness       Glass      Diameter
> OBJ    Infinity   Infinity                         0
>   1    1553.713   11.77975      N-BAK4           130
>   2   -874.3206   37.13928                       130             
> STO    Infinity   9.911175                  119.7946
>   4   -185.9477          8     N-KZFS4           130
>   5    192.3444   16.16369          F5           130
>   6    1279.523   20.27615       N-BK7           130
>   7   -180.3021   1517.568                  128.0278
> IMA   -1440.639                             26.02212
>
>does about as well (maybe a tad better across the field) with
>shallower curves.  However, it also does not match up well with
>the in-hand glass.
>

On the other hand:
 
Surf      Radius  Thickness       Glass      Diameter
 OBJ    Infinity   Infinity                         0
   1     1170.74       11.4       N-BK7           130
   2       -1322   46.92198                       130
 STO    Infinity   8.286125                  119.7042
   4    -220.304          8     N-KZFS4           130
   5     220.304     11.675      S-TIM3           130
   6     458.333         21      N-BAK4           130
   7    -220.304   1497.803                  126.1411
 IMA    -999.302                             26.01402

uses all ECO glass, has shallow curves, and has one other
obvious construction advantage.  In spite of the equality
constraints, the visual Strehl is still 0.988 at 13 mm.  I
suspect some would have serious qualms about leaving an
exposed surface if these two were attempted with the older
KzFSN4 instead of N-KzFS4 -- I have heard rumor that that
stuff could be a beast.

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