Pentax K-7 Performance, Timings, and Image Quality

December 17, 2009 by Jerry Jackson Reads (5,606)

Still, the exterior features of the Pentax K-7 aren’t really what make it so special. For that, we have to look inside. Considering that the K-7 only costs a little more than a Nikon D90 it’s fair to say Pentax packs a great deal of performance into a small and affordable package.

Shooting Performance
For starters, the K-7 is the fastest Pentax DSLR ever made with a top burst shooting speed of 5.2 frames per second (40 JPEGs, 15 RAW/PEF or 14 RAW/DNG). As you can see in the studio tests below, the K-7 performs quite well in terms of shutter lag and does an okay job with AF acquisition, but comes up a little short compared to the Nikon D300S and Canon 7D. Still, the K-7 is more than capable of exceeding the performance needs of most photographers. That being said, it’s worth noting that the continuous shooting performance drops sharply if you activate the various in-camera editing features like extended dynamic range, or lens correction.

Shutter Lag (press-to-capture, pre-focused)

Camera Time (seconds)
Canon EOS 7D 0.02
Pentax K-7 0.02
Nikon D300S 0.02
Olympus E-620 0.02

AF Acquisition (press-to-capture, no pre-focus)

Camera Time (seconds)
Nikon D300S 0.15
Canon EOS 7D 0.17
Pentax K-7 0.29
Olympus E-620 0.32

Continuous Shooting

Camera Frames Framerate*
Canon EOS 7D 160 8 fps
Nikon D300S 14 6.9 fps
Pentax K-7 19 5.3 fps
Olympus E-620 6 4.1 fps

*Note: Continuous shooting framerates are based on the camera’s fastest full-resolution JPEG continuous shooting mode, using the fastest media type available (300x CF, SDHC, etc.). “Frames” notes the number of captures recorded per burst before the camera stops/slows to clear the buffer.

Anyone who’s still foolish enough to think Pentax cameras aren’t fast enough for professional motorsports needs to spend an afternoon at the track with the K-7. Pentax also claims that the 11-point autofocus system in the K-7 uses improved focus algorithms over previous Pentax cameras. After all of my testing of the K-7, I can confirm it is noticeably faster than any Pentax camera I’ve previously used.

The one exception in terms of speed is the contrast-detection AF used in the camera’s live view mode. Our review unit of the K-7 suffered from horribly slow AF lag when using live view mode with the camera’s LCD. True, most DSLR cameras with live view mode suffer from slow contrast-detection AF, but the contrast-detection AF on the K-7 is so slow that it is essentially unusable unless you’re photographing a stationary subject and your camera is mounted on a tripod.

The video below shows an example of just how slow the K-7 is when shooting in live view mode. Not only does the contrast-detection AF system take a long time to lock focus, but it takes time to reset the focus if you press the button again … even if the subject was already in focus. Keep in mind that this example was shot in our studio with a stationary subject, the K-7 was mounted on a tripod, and the lighting was very good. In a “real world” shooting situation the contrast-detection AF is even slower.

Lens Performance
Using a variant of the maker’s classic K mount, the K-7 is designed for “legacy” lens support, handling nearly any Pentax K-mount lens (as well as many screw-mount and medium-format lens) with comparatively little hassle or fuss. And with in-camera IS, every lens is a stabilized lens. While you won’t get the huge lens selection – and particularly, the range of fast zooms and longer telephotos – offered by Canon and Nikon, if you like shooting primes, Pentax currently makes some of the best, most interesting ones on the market. In fact, our staff is so impressed with the Pentax Limited series of prime lenses that we were sad to see that Pentax didn’t offer a K-7 kit with the Pentax DA 40mm f/2.8 Limited prime lens (a staff favorite).

We tested the K-7 with a range of Pentax lenses, but most of the three lenses we used most frequently were the DA 40mm f/2.8 Limited prime lens and Pentax’s two newest weather sealed zoom lenses: the Pentax DA 18-55mm f/3.5-5.6 AL WR and the DA 50-200MM F/4-5.6 ED WR. We didn’t notice any major issues with the lenses used during our tests, but the 18-55mm lens does have some visible distortion at the wide angle end of the lens … which is easily corrected with the K-7’s in-camera lens correction.

Video Quality
Of course, one of the big new features with the K-7 is the ability to record HD video at 1280×720 (16:9 widescreen aspect ratio), 1536×1024 (3:2 aspect ratio) or 640×416 (3:2) resolution all at 30 frames per second. We shot several sample videos with the K-7 at the various resolution settings and never had any issues with video quality.

More to the point, the video quality seems on par with other DSLRs capable of recording video. One key difference with the K-7 compared to lower cost DSLRs is that the K-7 has an external microphone terminal for recording stereo sound … a good thing to have since the camera’s in-body Shake Reduction feature can cause the built-in microphone to record excess noise. An HDMI port built into the K-7 also makes it easy to show your videos directly on your HDTV.

Pentax K-7

Image Quality
When it comes to image quality, I honestly feel like kissing the Pentax engineers responsible for the K-7. Pentax finally seems to have figured out how to build a camera with extremely accurate white balance. Whether I was shooting under strong incandescent light or horrible mixed lighting conditions the K-7 almost always managed to deliver perfect white balance for accurate color reproduction even with JPEGs.

Pentax K-7
Auto White Balance, 3200k incandescent light

I only encountered one shooting environment with mixed lighting where I ended up with unusual white balance after more than a month of shooting. In that situation I switched to shooting RAW/PEF and corrected the white balance in Photoshop without any problems. The most important thing to notice in the sample image below is that the colors look exactly the way they should despite horrible mixed lighting.

Pentax K-7

I’m also pretty impressed with the K-7’s selection of “digital filters,” which provide a range of in-camera emulators for editing photos without Photoshop. Some of my favorites include “toy camera,” “water color,” “star burst,” or the surprisingly useful “extract color” filter. Still, even if you never use a single in-camera digital filter it’s safe to say you’ll be impressed by the quality of the images coming out of this camera.

Pentax K-7

The K-7 also includes a High Dynamic Range (HDR) image capture mode that captures three images and then combines them in-camera to widen the exposure range and bring out details in shadows, midtones, and highlights. There’s even an in-camera Lens Correction tool that electronically adjusts for lens distortion and lateral chromatic aberrations so you won’t have to make those corrections on your computer. If that wasn’t impressive enough, working photographers will surely appreciate the fact that the K-7 can embed copyright information in the metatag data of every image, so you won’t have to worry as much about proving image ownership.

Image quality at all ISO settings seems noticeably superior to the K10D or K20D in terms of color accuracy, and image noise is better at ISO 800 and below. If you already own a K20D you might not see much improvement in terms of ISO noise at 1600 and above, but the high ISO image quality is still very good.

Pentax K-7
ISO 100
Pentax K-7
ISO 100, 100% crop
Pentax K-7
ISO 200
Pentax K-7
ISO 200, 100% crop
Pentax K-7
ISO 400
Pentax K-7
ISO 400, 100% crop
Pentax K-7
ISO 800
Pentax K-7
ISO 800, 100% crop
Pentax K-7
ISO 1600
Pentax K-7
ISO 1600, 100% crop
Pentax K-7
ISO 3200
Pentax K-7
ISO 3200. 100% crop

Additional Sample Images

Pentax K-7 Pentax K-7
Pentax K-7 Pentax K-7



All content posted on TechnologyGuide is granted to TechnologyGuide with electronic publishing rights in perpetuity, as all content posted on this site becomes a part of the community.