Originally posted by Cannikin It was a very, very dark room; dark enough that I had trouble seeing through the viewfinder. I wanted it such that the only real source of light is the flash to eliminate any other variables. I just used these settings because it's what P mode on the K-5 gave me with the flash on.
But it shouldn't matter what the shutter/aperture are. Unless I'm mistaken, the whole point of P-TTL is such that it pre-flashes to examine how the light affects the scene and adjusts the flash power accordingly. The K-x gives me basically the exact same exposure every time, no matter what I set the settings to. Yeah, I've noticed that the K-x consistently looks rather dark with the flash, but it is very consistent in giving me that exact same exposure each time.
In my testing with the K-5, testing with various apertures and shutter speeds, it's pretty clear that the flash is firing at full power every single time. f/5.6 produces an image that is roughly one stop less overexposed, f/8 one stop less, and so on. It's obvious the flash is not adjusting its power at all.
I'm wondering whether your flash is communicating correctly with the camera.
I don't have the K-5 yet, but I had a similar initial issue with the K-7.
Does the LCD screen on the Flash say "P-TTL"
Has the Flash Icon in the viewfinder stopped blinking ? - it should show a steady flash icon once it recognises the P-TTL flash.
Without both these two showing proper flash-camera communication, the flash will fire at Full Power, regardless.
When you set ISO 3200, and direct flash, is the minimum/maximum indicator on the flash LCD screen blinking ? (indicating too close within minimum P-TTL flash range).
...Edit...I just checked the AF540 manual. At ISO3200, 50mm focal length, the minimum direct flash range at f/5.6 is about 18 feet. Anything closer will be overexposed. If you add ambient lighting in a reasonably lit room, the minimum will be greater.