How do you specify a custom imaging lens?

The parts of the imaging system need to be considered including source of illumination, object observed, imaging optics used such as lenses and mirrors, and how does the image appear on the sensor. Key product requirements to ask are first, what are we imaging. For example, how close or far is it, what is its smallest feature to image, size of area imaged, is object opaque or translucent. Second, lens details are needed such as zoom, magnification, depth of field. Third, what is collecting the image, such as eye or sensor. Fourth, any mechanical limitations such as space and angles. Fifth, how is the scene lighting including wavelength and chromatic aberrations. Sixth are business questions. Seven, a sketch may be included to clarify things,