In program + auto-ISO mode, for any given exposure value, the camera calculates values for aperture, shutter speed and ISO. As the exposure value goes down, limits are hit in this order (with the M.Zuiko 12-40 f2.8 ):
- Aperture opens until it hits maximum, f2.8 for the lens in question.
- Then, the shutter speed drops, stopping at 1/60th with the lens in question, and the flash "Slow Limit" set to 1/60th.
- Then, the ISO climbs to the whatever upper bound is set, I use 3200 typically.
- ISO and aperture are at hard limits, so the shutter speed drops.
With the mechanical or first-curtain electronic + manual shutter, this behavior is consistent with previous firmware versions. But with the new fully electronic shutter, at step 2, the shutter speed drops to an
eyebrow raising 1/13th before the camera resorts to cranking up the ISO.
Speculation on whether this is a bug or a feature? I'm inclined to think of it as a bug, unless getting the mechanical shutter out of the picture, the stabilization is that much better. But leaning toward the bug side, even if that were true, 1/13th is rarely appropriate for any subject that moves.