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HDR capture mode on this new SLR combines three shots for an estimated 17 stop EV range
Please check out our NewsDesk coverage for the full stats on the K-7, including HD video, sensor microadjustments, the 921K dot LCD, smaller form factor, new battery grip with dedicated back AF button, and everything else about this great new advanced SLR from the Pentax that doesn't deal specifically with High Dynamic Range Imaging. This piece is just about HDRI with the K-7.
As you may know, I am a huge advocate of High Dynamic Range Imaging. I've written books on the subject, and I am always looking at the potential HDRI capabilities of new cameras each product cycle.
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!
Tone mapping appears to be applied by a very restrained Local Operator according to two sets of rules: Standard or Strong. Standard reports in the EXIF as HDR 1 and Strong as HDR 2.
"Standard" is a touch more subtle and photorealistic with more overall global contrast than "Strong"; which pulls more details out of microcontrast pixel environments but has less overall global contrast. When a shot has large areas of solid color and texture, such as smooth interior walls, you may notice bands of gray masking artifacts aka "haloing" with the Strong setting–the same as if aggressive tone mapping is applied on the computer to areas lacking microcontrast. The best bet is to try both settings and see which is more pleasing. In many ways, the in-camera tone map operator of the K-7 behaves in a manner similarly to the TMO in Corel's Paint Shop Photo Pro X2 with its simple and subdued "Strength" and "Clarity" sliders. (In fact, the whole in-camera HDR Capture experience with the K-7 is quite similar to the PSPX2 workpath where the true High Dynamic Range Image is always in the background and not able to be saved as a high-bit file by the user.)
Our slideshows show a few samples of in-camera HDR with the Pentax K-7, along with a comparison against single-image shots in "Bright" color settings, with Highlight and Shadow adjustments off and maxed out. As you can see, the HDR shots have much more detail than either of the single-shot output images. All shots are straight from camera, but have been resized for screen display.
In-camera HDR with the Pentax K-7 versus in-camera bracketing and on-computer HDR merging and mapping
In-camera HDR with the Pentax K-7 is impressive, and certainly takes a lot of the computer gruntwork, stress, frustration and reward out of the High Dynamic Range process for many a scene with a very high contrast ratio. Overall the process is very painless, and there are many practical applications where the end result is what matters most–not the process. Longtime HDRI shooters may bemoan the loss of the challenge and cachet of working up multiple source images in specialized software with this simple solution, and in no way is it time for seasoned HDRI shooters to abandon FDRTools, Adobe Photoshop CS4, Photomatix Pro or Dynamic Photo HDR for more complete control in Tone Map settings. But for many a photographer wishing to quickly overcome bald skies, clipped shadows and blown highlights, the Pentax K-7's HDR Capture mode will be their new best friend.
My advice for settings and choices of in-camera processing versus old-fashioned(!) multiple bracketed source images into a specialized HDR program for seasoned HDR photographers echoes the advice I offer on page 37 of Practical HDRI, RAW versus JPEG versus RAW plus JPEG:
Shoot both! Capture the scene with your bracketed multiple source images in DNG/RAW+JPEG for nuanced tweaking in your favorite HDR digital darkroom program, and then switch the camera to HDR Capture and reshoot the scene with the K-7's impressive in-camera HDR processing. If the in-camera processing nails it to your satisfaction, you save yourself computer time–leaving more time to be out shooting! But if you think you can push or pull the high-bit pixels more, you've got that choice when shooting both ways.
The Pentax K-7 is a game changer. The era of in-camera HDR begins today.
And we are off to a very good start!
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