Prior Olympus User. Good to know ECFS is on by default - shutter a little louder than I expected btw - not bad though.
Just got my RP as well and am curious about this ECFS thingie.
IF what you're talking about is electronic shutter (Silent Shooting) and not something to do with flash then my understanding is different. I have read that the only way you can enable electronic shutter is in "silent shooting" Scene (auto) mode.
Of course if I'm mistaken about all this then......nevermind.
Full electronic shutter ("silent shutter mode") (exposure is completely done electronically with the mechanical shutter not used at all), is only available via the scene mode.
EFCS is something different. EFCS is electronic FIRST CURTAIN shutter.
Prior to availability of EFCS, all mirrorless cameras exposed by first closing the mechanical shutter completely (to blackout the sensor) when the shutter button was pressed. This was followed by the exposure, when the mechanical shutter was lifted over the sensor at the set shutter speed to complete the exposure, followed by the complete opening of the shutter again once the exposure was completed (to allow Live View again).
That first full shutter closure, before the exposure, was what caused shutter shock, as the slap of the moving shutter closing would reverberate through the body for long enough to affect the actual exposure at certain speeds and with certain lenses.
So, what most mirrorless camera manufacturers have done is implement a method of using an electronic sensor blackout before the exposure rather than using a mechanical first curtain shutter based blackout. The actual exposure is still done with the mechanical shutter moving up the sensor; it's just the initial blackout before that that's done electronically with EFCS.
EFCS avoids two problems: First, there's no shutter shock from that first curtain mechanical shutter slap, and second, there's no rolling shutter effect that can happen when you shoot moving objects with a completely electronic (no mechanical components at all) shutter.
EFCS is a neat way to get around the drawbacks of both mechanical and electronic shutter functionality. (At least until a true global shutter is introduced, which will eliminate the need for ANY mechanical shutter AND prevent rolling shutter effect, AND be totally silent. However, that technology, while it does exist, is not yet developed enough for cameras with CMOS technology large sensors at this point in time).
-J