Pentax K-r: Performance

December 10, 2010 by Howard Creech Reads (9,326)
Editor's Rating

Ratings Breakdown (1-10)

    • Image/Video Quality
    • 8
    • Features
    • 8
    • Design / Ease of Use
    • 7
    • Performance
    • 8
    • Expandability
    • 7
    • Total Score:
    • 7.60
    • Rating 1 to 10, top score 10

Shutterbugs who shell out $800 for a DSLR generally expect a pretty substantial return (in terms of performance) for those hard earned dollars. The Pentax K-r isn’t the fastest camera in its class, but it does perform credibly across the board and a two one hundredths of a second (0.02 versus 0.04) difference is essentially no difference at all.

Shooting Performance
The Pentax K-r starts up very quickly, essentially “real time” – turn the camera on and it is ready go. Shutter lag is 0.04 of a second, quick enough for just about anything this camera’s target audience is likely to try. AF acquisition is 0.19 of a second which is very close to the AF acquisition times of the K-r’s competition. The K-r’s continuous shooting rate is 6.4 fps. In the timing arena the Pentax K-r isn’t the fastest DSLR out, but it is competitive across the board.

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

Camera Time (seconds)
Canon Rebel T2i 0.02
Nikon D5000 0.02
Sony Alpha SLT-A55V 0.04
Pentax K-r 0.04

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

Camera Time (seconds)
Sony Alpha SLT-A55V 0.16
Canon Rebel T2i 0.18
Nikon D5000 0.19
Pentax K-r 0.19

Continuous Shooting

Camera Frames Framerate*
Sony Alpha SLT-A55V 17 10.8
Pentax K-r 29 6.4
Nikon D5000 30 3.9
Canon Rebel T2i 170 3.7

* 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.

The Pentax K-r provides the following focus modes – auto, AF.S (single – with focus lock), AF-C (continuous), 5-point or 11-point Auto, Select (AF point), or Center AF. The K-r uses an updated (SAFOX IX) version of the same TTL phase-matching 11 AF point (9 cross type in the center) contrast detection auto focus system as the Pentax K-7. The camera automatically selects the closest AF point to the subject (closest subject priority) and the selected AF point glows red once focus is locked.

AF is consistently fast and accurate even in dull lighting. Continuous AF (which continually adjusts focus as the shooter follows a moving subject) works pretty nicely in most action/sports shooting situations. The K-r’s Face Recognition AF mode works nicely, identifying up to 16 people in the frame, but it needs a couple of seconds to lock on a non-moving subject. Live View can be used in the continuous (AF-C) shooting mode with no restrictions on the 6 fps rate since the mirror is locked up. The K-r’s Face Recognition AF mode works nicely, identifying up to 16 people in the frame, but it needs a couple of seconds to lock on a non-moving subject. Live View can be used in the continuous (AF-C) shooting mode with no restrictions on the 6 fps rate since the mirror is locked up.

Lens Performance
Pentax KAF3, KAF2, KAF-, and K-mount lenses can be mounted on the K-r , but older lenses have restrictions. My tests were conducted with the SMC Pentax DA 18mm-55mm f/3.5-f/5.6 AL kit zoom. The 18-55mm kit is equivalent to a 27-83mm zoom. Most DSLR manufacturers offer a kit lens, generally a 3x zoom designed to sell with their entry-level and mid-level DSLRs at the lowest possible combo price. Most OEM producers build these kit lenses as simply as possible using as much plastic as they can get away with.

Pentax K-r

Pentax’s kit zoom is a little different. Pentax attempted to produce an inexpensive optic which feels well-made and offers some genuinely impressive performance for serious shooters. These “extra” features include better construction with less reliance on cheaper materials, a non-rotating front element for filter users, and a manual focus option. Pentax’s 18-55mm kit lens has received very favorable reviews compared to kit lenses from Canon and Nikon.

The K-r’s kit zoom is surprisingly good, but images do show some noticeable barrel distortion (straight lines bow out from the center of the frame) at the wide-angle end of the zoom range. Pincushion distortion (straight lines bow in toward the center of the frame) is lower than average at the telephoto end of the zoom. Chromatic aberration (purple fringing) is very well controlled.

Pentax K-r Sample Image

One of the K-r’s most useful features is its image stabilization system. Pentax’s IS system (Pentax calls this SR – shake reduction) neutralizes camera shake by vibrating the CCD sensor to cancel out involuntary camera movement. Most camera manufacturers (including Canon and Nikon) accomplish IS by shifting lens elements to counteract for camera shake. The greatest benefit of camera body IS systems is that they work with every lens mounted, not just with (more expensive) IS or VR lenses. With image stabilization enabled, Pentax K-r users can shoot at shutter speeds up to 3 EVs slower than would have been possible without image stabilization.

The K-r’s built-in pop-up multi-mode P-TTL flash (auto, manual, manual flash + red-eye reduction, slow speed synch, slow speed synch + red-eye reduction, second (trailing) curtain synch, wireless flash, and flash-off. The K-r’s flash automatically pops up when needed – if ambient lighting isn’t sufficient or to add fill-flash in back lit situations. The K-r’s built-in flash provides a decent selection of lighting options, but the fastest flash synch speed is only 1/180th of a second – which is fairly pedestrian. Guide Number is 15.6 at ISO 200/m. Coverage is equivalent to 28mm and the maximum flash range is about 16 feet. Flash Exposure Compensation: -2 EV – +1EV (1/2EV steps). The K-r also provides a dedicated flash hot shoe for mounting Pentax Speedlights like the AF360FGZ or the more powerful AF540FGZ. Third party flash units can be used, but not with full compatibility.

Unique to the Pentax K-r is its new Dual Power source feature. Most current DSLRs draw their juice from proprietary rechargeable Lithium-ion battery packs. Rechargeable Lithium-ion batteries are lighter (and require less physical space) than AA batteries, but some shooters like AA batteries so Pentax’s engineers designed a camera that allows the use of both power sources – the best of both worlds. Battery life with the new D-LI109 lithium-ion battery pack is rated (by Pentax) at around 470 images (with 50% flash usage) and playback time is rated at 300 minutes. Based on my experiences with the K-r, I’d say that figure is probably inflated by about 25%.

The Pentax K-r stores images to SD and SDHC flash memory cards after a firmware update with SDXC cards as well. Images can be saved in JPEG, compressed RAW, and uncompressed RAW formats.

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