Apertimestep

Apertimestep is a conceptual parameter used in imaging, computer graphics, and optical simulations to describe the temporal sampling interval associated with the lens aperture during exposure or rendering. It represents the duration over which light is integrated as the aperture modulates the amount of light reaching the sensor or as the simulation samples different aperture states.

In real cameras, exposure is governed by shutter speed and aperture. While the aperture primarily controls light amount and depth of field, some advanced models treat the aperture as changing over time due to blade motion or adaptive optics. In these contexts, the aperture timestep helps model the resulting motion blur and dynamic depth of field by defining how long the aperture remains in a given state during an exposure.

In computational photography and rendering, aperture timestep is used to control temporal sampling when simulating depth of field and bokeh. By taking multiple samples at different times or across different angular positions of the lens and averaging them, renderers can produce more accurate blur effects in scenes with motion or changing focus. It can also approximate light integration through an aperture in dynamic scenes where objects move during the exposure.

Implementation notes: In a renderer, the aperture timestep is often chosen as a fraction of the frame time, balancing the desired level of motion blur with rendering performance. Adaptive schemes may adjust the timestep based on scene motion or lens dynamics.

See also: Depth of field, motion blur, lens, exposure, shutter speed.