[ale78]

It seems like the pop up flash behavior on the K-7 acts differently than on the K100DS.

I took a picture with each camera in Av mode without flash in a dimly lit room at 50mm, f2.8, auto ISO.
K-7 selected a 1/8 shutter speed and ISO 1600.
K100DS selected a 1/8 shutter speed and ISO 1600.
Both photos were properly exposed.

I popped up the flash on the cameras and took another picture on each.
K-7 selected a 1/100 shutter speed and ISO 1600.
K100DS selected a 1/60 shutter speed and ISO 200.
Both shots were slightly overexposed but the K-7 was more so.

[kittykat46]

My guess is f/2.8 at ISO1600 is likely outside the P-TTL's exposure range - the flash has both a maximum and minimum power capability.
The response I got was the Auto ISO will kick down the sensitivity when the flash is turned on - I ended up with ISO 800, something like that on AutoISO+flash, then it exposes correctly.
It was all automatic, I didn't even have to worry about it.

The AutoISO setting on the K100DS is "broken" with flash. It will always set ISO200 with flash. Whenever you need to increase ISO due to insufficient flash range, you have to do it manually.