Camera
µm
Lens & geometry
mm
mm
–
nm
Motion (optional)
mm/s
µs
What this means
Imaging geometry
Results
Radiometry & illumination advanced
Relative illumination falls toward the corners as roughly cos⁴θ (natural vignetting) plus
any pupil-aberration effect. The exposure estimate is a first-order radiometric check: it scales the corner-to-centre
brightness and the light-gathering (1/working-f/#²) so you can compare lens speeds — not an absolute photometric model.
Object-space resolution vs f-number
Reading this plot: the flat line is the sensor sampling limit (2 pixels per line pair,
mapped to object space); the rising line is the diffraction limit (Airy-based, at working f/#). Operating left of
the crossing wastes lens performance on sampling; right of it, stopping down further costs real resolution.
Depth of field, however, keeps improving with higher f/# — choose the smallest f/# that meets your DoF.