[ATM] F8 glass?

[Richard F.L.R. Snashall]

  On 2/22/2011 9:26 AM, Richard F.L.R. Snashall wrote:
>  On 1/28/2011 3:58 PM, Guy Brandenburg wrote:
>> Anybody ever heard of F8 glass (not an f/8 lens or mirror) as in a 
>> Schott
>> appellation like KSFSN2 or BK4 or some such thing?
>>   Guy Brandenburg, Washington, DC
>>
>
> Don't you just love it when serendipity hits:
>

And, there's always:

Title: Ptz15-59x
150 mm f/7.5 Petzval

Surf     Radius      Thickness   Glass  Diameter

  STO   Infinity      -3.616418               150
    2   779.5115             15     BK7       156
    3  -779.5115            7.5      F2       156
    4  -13038.73  2.916903e-006      F2       156
    5  -13037.26       920.2279               156*
    6     525.19             11      K5       110
    7    -525.19            5.5      F8       110
    8   3204.424       503.6587               110
  IMA  -1118.926                             43.3

* High order correction: 1.89139e-12*r^4 - 2.07253e-16*r^6