Use F-stop and shutter speed for exposure

[lizGYM66]

Is it not possible to use F-stops, shutter speed and ISO values for exposure in Arnold? Is the only option the Exposure imager which is in F-stops?

[peter_horvath]

Physical camera parameters (f-stop, shutter speed and ISO) do not affect exposure in Arnold. The exposure imager does not support physical parameters either, it has the same exposure value control than the Arnold camera. It is a numerical scale and increases or decreases brightness in powers of two. The imager documentation mentioning f-stops is misleading, it should just say stops.

[maxtarpini]

You should be able to use python scripting and attach this to any exposure parameter ..

import math

def compute_ev(fstop: float, shutter_speed: float, iso: float) -> float:
    return math.log2((fstop * fstop) / shutter_speed * (100.0 / iso))

.. while negating the result.. because :

exposure = 2.0 ** (-compute_ev(fstop, shutter_speed, iso))