[cali92rs]

ETTR +2 stops and your shutter speed changes to 1/25. The slower shutter will allow more total noise to creep in but you'll also have more signal. Then you dial exposure down 2 stops during processing and everything, signal+noise, returns closer to the level as if you perfectly exposed.

The idea is to not vary ISO, leave it as close to base as possible, and only lessen your shutter speed.
THe increase in noise due to these shutter speeds is really negligible and is much more influenced by ISO. It's only when you get into really long shutter speeds that it will really effect noise.

[fs999]

Thank you for your reply. I will re-post my question about K3 on K3 forum.
And regarding the exposure, I didn't understand about this -1EV setting because if you spot meter on highlights and bias the exposure until it's pushed to the right on histogram, you won't have any overexposure issues. And I have discovered that +3EV is the sweet spot on my K5. The in-camera JPG will be very bright with red blinkies, but the RAW files never showed any clippings when I load the files on LR.
But perhaps it may not be applicable if you are using other metering methods. For me it works best because my shooting style and conditions allows me to use spot metering and using manual exposure.

I use Multi-Segment meter. Because I take often shots when driving on the road, or macros...