> I'm aware that pov's camera is a pinhole.
>
> I'm starting out on a technical rendering exercise, where I need to make
> pov's output look as much like a real camera.
>
> What I know, is my image sensor size, and the focal length of a given lens
> in our system, and what field of view it gives.
>
> I would like to be able to vary the focal length, and get the 
> corresponding
> change in field of view, as well as the appropriate distortion as we get
> into the lenses that have FOVs like 120 degrees.
>
> Is this available as a macro or .inc somewhere?

You can set the horizontal FOV with the angle keyword in a camera.

Focal blur can be defined with the aperture, blur_samples, focal_point,
confidence, and variance keywords. With the right settings, and good
objects the render is nearly indistinguishable from a photo.

Aperture varries in the same manner as f-stops. An aperture of 0.125
very roughly corresponds to an f/8 setting. However, since the POV
simulation of focal blur is not based on a model of a lens, this is not
100% correlation. In a POV camera the depth of field varies
*differently* in relation to the distance to the focal_point than how it
varies in a RL camera.  POV ray-traces from the camera to the
scene and returns the color, with focal blur it just uses some
Montecarlo randomization to sample some extra ray-traces to find
an average, there is no diminishment of light at a distance like in a
RL camera.  The number of samples per pixel to take are set with
blur_samples, confidence, and variance; the number of ray-traces
has a big impact on render speed.

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