Pentax K-3 Performance

Generally very good performance for a prosumer DSLR, but slow buffer clearing.

Startup was a touch slow for a prosumer DSLR, but shutdown was fast. Buffer clearing times were a little slow for the class of camera, though buffer depths were excellent.

Play to Record was very fast as was displaying a recorded image, but switching from Record to Play was a touch sluggish.

The shutter lag numbers above measure time from shutter button press to image capture, with the lens already set to the correct focal distance. This largely removes the issue of differences in lens focusing speed, and measures how fast the camera can measure and act on focus information. In this metric, the Pentax K-3 was a touch faster than average for a prosumer DSLR, and noticeably faster than the K-5 II. The K-3 required 0.138 second for full AF when using Single-point (center) AF mode (our default full AF lag test). Enabling the flash in this AF mode increased lag to 0.325 second, though. Full AF shutter lag in Auto area AF mode was only a bit slower than single area at 0.157 second.

In a test where we defocused the kit lens between shots, autofocus lag averaged 0.593 second, giving you an idea of real-world performance. But that will vary depending on the amount of defocus, the lens mounted, subject type, lighting, etc.

Manual focus lag time was only 0.097 second, which is quite good. When prefocused, shutter lag was 0.096 second which while fast, isn't as fast as some competing models.

As expected, the Pentax K-3's Live View mode was much slower to focus. Full autofocus shutter lag was 1.005 seconds using wide-area contrast-detect AF mode. This increased slightly to 1.014 seconds using Spot AF mode. (Unlike prior models, the K-3 does not offer a phase-detect AF mode in Live View.) Prefocused shutter lag was quite good for Live View mode, however, at 0.226 second.

Shot-to-shot cycle times were good, at 0.79 second for Large/Premium JPEG, 0.64 second for DNG and 0.69 second for DNG + L/P JPEG files. That's quite a bit slower than the K-5 II's ~0.4 second cycle times, but still fairly good.

Continuous mode speed was very good for a prosumer DSLR, at about 7.1 frames per second regardless of file type. That's a little faster than the ~6.7 fps we got for the K-5 II, however quite a bit slower than Pentax's rating of 8.3 frames per second for the K-3. (We shoot all our continuous mode tests at ISO 200, though, and Pentax specifies 8.3 fps at ISO 100.)

The Pentax K-3's buffer depths were excellent for a prosumer DSLR, especially considering the burst rates and resolution. The K-3 managed 75 L/P JPEGs, 24 DNGs and 25 DNG + L/P JPEG frames before slowing down. (You'll likely do better with the same speed card, as the target image we use for our tests is designed to be difficult to compress.) Buffer clearing was sluggish, though, taking from 24 to 37 seconds to clear after maximum length bursts, however keep in mind buffer depths are quite generous.

The Pentax K-3's flash took 2.3 seconds to recharge after a full-power shot, which is quite fast.

Connected to a computer with a USB 3.0 port, downloads were the fastest we've tested thus far, but it's possible the transfer rate could be even faster with different computer hardware.

Bottom line, the Pentax K-3's performance is generally very good, with fast autofocus speeds, good shutter lag, and fast burst modes with deep buffers. Buffer clearing is however slow for a prosumer model, but perhaps not a surprise given the deep buffers and fairly large files.

Battery Life
Below average battery life for a prosumer DSLR.

The Pentax K-3 uses a custom rechargeable lithium-ion battery for power, and ships with a charger. Battery life is below average for a prosumer model so you'll probably want to get a second battery and also consider purchasing the optional battery grip which can double battery life with a second battery.

The table above shows the number of shots the camera is capable of (on either a fresh set of disposable batteries or a fully-charged rechargeable battery as appropriate), based on CIPA battery-life and/or manufacturer standard test conditions.

(Interested readers can find an English translation of the CIPA DC-002 standards document here. (180K PDF document))