Transmission of the optics As a zeroth order assumption, the transmission of the optics is assumed to be constant for all angles $\theta$ relative to the optical axis in the full camera field-of-view. For cameras with a narrow field-of-view this can be considered to be a justifiable assumption. Whether this is the case for optics with a medium field-of-view, $54$, remains an open question. As an aside, a first order correction can be obtained from the experiment outlined in section 5.4.