I have been using my Olympus PEN-F camera in the program mode with the electronic shutter and auto ISO in order to keep my photography silent when photographing around people in changing light conditions. When photographing this way, I noticed that the camera’s bias is towards selecting slow shutter speeds before raising the ISO level. Often the shutter speeds were too slow to stop subject motion until Olympus published the software update that enabled me to set a floor level for shutter speed.
While trying some other features of the camera, I noticed something. The camera appears to have a different program curve for different shutter mechanisms; i.e. the camera selects different values for ISO and shutter speed for different shutter types.
The literature is clear about the effects of rolling shutter effects when using the electronic shutter. In addition, the specs show that faster shutter rates can be obtained with the electronic vice mechanical shutter. Based on that information I assumed that when using the electronic shutter that the chosen shutter rates would be faster than those used with the mechanical shutter, if the camera software used different program curves. Not so. The reverse is true, at least in some sections of the program curve. When I used either the mechanical or the hybrid shutter the chosen ISOs were higher as were the shutter rates. I expect that the reasons for the different program curves have to do with shutter shock, etc. Olympus is probably biasing the different curves to minimize the issues that arise when using different shutters.
Has anyone found an explanation of the differences between the Olympus program curves that are dependent on shutter modes, or does anyone have some other explanations?