[IMPOSSIBLE] Variable aperture or ISO in single exposure(frame)

[Mantanuska]

Not sure if there has already been something similar proposed since I am not quite sure how to succinctly describe what I mean.

Essentially, it would be nice to have something that produces a similar effect to setting the flash to second curtain for a long exposure, but instead of increasing the exposure at the end of the shot using a flash, increase it by adjusting the aperture and ISO.

For instance, it would be nice to do a long exposure at night of a moving subject, getting the motion blur as well as getting a frozen image of the subject.

This concept could be developed further by noting the EV determined by the light meter and then automatically handle the aperture and ISO change by calculating an equivalent exposure while satisfying a specified shutter speed at which the subject would appear still (depending on distance and focal length) so that the combination of the longer , less exposed segment of the frame and the shorter, more exposed segment of the frame would still end up resulting in a correctly exposed image.

As far as I know, I do not think this could be done in post, even with current ML features because of the lag time between frames that would result in a gap in the blur