(t
(error "Must set two, and only two, of the parameters: image-distance, object-distance, and focal-length."))))
-(defun close-up (&key focal-length object-distance image-distance magnification (units :feet) &aux bellows-factor)
+(defun close-up (&key focal-length object-distance image-distance magnification (units :feet))
"Computes the parameters for focusing closer than infinity.
Requires two, and only two, of the input parameters.
Returns: focal-length object-distance image-distance magnification bellows-factor."