found this
http://www.adorama.com/alc/blogartic...mid=80238&jb=0
Even before factoring in the dedicated first of its kind in-camera High Dynamic Range capture mode, the Pentax K-7 is a winner for HDRI shooters. Many other manufacturers would be wise to take a look at the creative controls and feature set that Pentax put into the K-7 for HDR-minded photographers, particularly at this $1,299 US List price point:
One-touch Auto Exposure Bracketing burst setting options.
+/-2 EV spacing for 3 or 5 shots for AEB capture gives an exposure range that is wide enough for many HDR scenes--something that is so lacking on too many models, including the Canon EOS 5D Mark II!
5.2 frames per second burst, offers fast capture of the AEB sequence.
User-selectable Adobe DNG RAW mode is already compatible with all HDR programs without waiting for the next round of RAW support upgrades.
This set of features alone is enough to the make the Pentax K-7 a 2009 HDR SLR All-Star. Add the impressive in-camera HDR processing to the mix, and it's in a league of its own.
In-Camera HDRI with the Pentax K-7
HDR Capture mode is accessed via the Menu button on the back of the camera, and is available in most shooting modes, except for Green, bulb, and video modes, for obvious reasons. It works with Live View or through the eyepiece framing, and works with all metering modes--just like Auto Exposure Bracketing. Honestly, until the shutter is fired, you wouldn't even know that you are in HDR Capture mode 1 (standard) or 2 (strong). You've just got to focus, frame, meter and fire the shutter, and the K-7 does the rest.
Here's what happens once you press the shutter: The mirror locks up, and the camera fires the shot based upon the current settings–just as it would fire off a single shot based on the current settings–but then it fires off a -3 EV and +3 EV shot on either side, for an effective estimated 17 EV merged captured range at ISO 100 (this etimate is based upon the DXOMark tests of the 14.6 Megapixel CMOS chip in the K20D at approximately 10.75 EV at ISO 100. We will update and append this article when DXOMark tests are completed on the K-7.)
Then it's all into the proverbial and actual black box with the three images. (I pried Pentax for details, but they wouldn't share the in-camera magic.) What comes out of the Black Box is an image crunched from the very wide dynamic range of the three source images that's tone mapped without excessive haloing, hypersaturation, or inversions, in JPEG format. There's no alignment, no deghosting, and no sensor-shift stabilization during HDR Capture. Use a tripod.
Note that I say the output image is JPEG format. It is also worth noting that HDR Capture is only accessible when the K-7 is set to JPEG-only capture output. Note that this does not necessarily mean that the K-7 is creating an HDR from three JPEGs and then tone mapping or simply applying low-bit Exposure Blending to three JPEGs rendered from the originally captured burst. All I can tell you with absolute certainty is that the output image from the HDR capture mode on the K-7 is an eight-bit JPEG. It wouldn't be practical or perhaps even possible for the three merged and mapped shots to be output as PEFs or DNGs, now would it?
It stands up to reason after reviewing several experimental images that that the K-7 is taking the linear RAW data from the three source shots and making a single high-bit High Dynamic Range Image that is then tone mapped during the 10-12 second processing time per HDR capture image. Creating JPEGs from the RAW data after A/D conversion would add an extra step. The only reason to think the merged image is sourced from JPEGs would be to shave some bits from the merging--but then the JPEG conversion would be adding a touch of time to the equation. Only the Pentax engineers know for sure, and they aren't telling us what's happening!