[OM] Re: f-stops (Was: Solstice web-site news)

[Steve Schaffner]

On Sat, 15 Jan 2005, Joe Gwinn wrote:

> The NA is n sin(a), where "n" is the refractive index of the 
> image-space medium and "a" is the half-angle of the converging code 
> of light.   For a photographic lens, the medium is air and so 
> n=1.0000.

n=1.0003 for air -- not that it matters in this context.

Steve Schaffner


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