"Matti Karnaattu" <nomail@nomail> wrote:
> >The "aperture" in PovRay is a square, not a cube.  And the area used by a
> >camera lens is a circle, not a sphere.
>
> I know that area used by in camera lens is circle but I dont know that
> Pov-Ray uses square. That's why I use circle in my calculations because I
> tried to fit area to cube :)
>
> Thanks for correction. Here is new formula:
>
>   aperture = distance_to_focal_point * pi ^ (1/2) / (f * 2)
>
> Matti

Just found this website while searching on Google...thought you guys might
be able to answer a question I have regarding aperture values on cameras.
I am aware that the f-stop refers to the number of times the apertures
diameter fits into the focal length of the lens, but what I don't
understand is the change in f-stops with a zoom lens with a floating
aperture.
ie a 28 - 80 mm lens with a max aperture of f3.5, max aperture at 28mm =
28mm/3.5 = 8mm diameter.  This seems way too small.  Also, if the max
aperture on this same lens changes to say f5.6 at 80 mm then the max
aperture's diameter at this focal length = 80mm/5.6 = 14.3 mm...
I'm confused - can anyone out there explain this for me?
(I will be eternally in your debt...oh, and what the hell is a POVray?)

Fenris

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