[ATM] Refractor perscription

[tomjan at ozemail.com.au (Thomas)]

Hi all,

I have just been working on a design to use some of the optical glass that Guy Brandenberg was offering last year.

Just to freshen everyone's memory heres what we know about the glass....

Vintage 1950's approx anyway.
The crown is listed as BSC with an n # of 1.517 and with an Abbe # of 64.5
The flint is stamped F620 with in pencil 620 and 36.2 the last is most likely the Abbe # the first short hand for the n # of 1.620

Both elements have a diameter of approx 5.5" with the crown having an edge thickness of .45" and the flint having an ET of 1.05" 

Anyway with all that said here is the design that I came up with today, I know there isn't really enough info for a really detailed analysis of this design, but it would be good if some one would be kind enough to run the numbers through a non OSLO package. (I have OSLO lt )

R1  -716.34mm
                        Crown (finished thickness estimated 11mm)
R2  1074.51mm 
                        Air 1mm thickness
R3 -1074.51mm 
                        Flint (finished thickness estimated (26mm)
R4  6569.28mm

OSLO gives an EFL of 1880mm, but my calculations gives me 2095.63mm.....

So I have an F/d of between F/14.8 and F/16.5 the final ratio will depend some what on how much lens' edge the cell will use for edge support.

Anyway there it is.

Clear Skies,
Thomas Janstrom
http://www.tjanstrom.com
http://www.norsewines.com.au