Pentax K-3 Review

Performance and Burst Mode

The Pentax K-3 features a new processor called PRIME III.  This is Pentax's fastest CPU to date. 

Considering that the K-3's 24-megapixel files are larger than the 16-megapixel files from the past two camera generations, an improvement to processing speed was much-needed.  Fine JPEG files from the K-3 are in the 11-13 Mb range, on average, and RAW files are about 30Mb.  Compared this to the K-5's 6-7 Mb JPEG files and 20Mb RAWs.

Despite the fact that it has to deal with larger files, the K-3 actually operates noticeably faster than its predecessor during everyday shooting.  The table below summarizes some key performance data that we obtained experimentally using a Sandisk Extreme Pro 95Mb/s card:

*on top of the time it takes to write the file to the card

Our tests show that the K-3 processes lens corrections much more quickly than the K-5 II.  They still add a noticeable amount of overhead when shooting a continuous burst, but they are nowhere as slow as on the K-5 II.  In addition, there isn't as much lag before the K-3's live view mode activates.  The K-5 II can save a single RAW or RAW+ shot faster than the K-3, but this is to be expected given the smaller file size.  However, the K-3 unlocks its menu system well before it is done writing, which still makes it feel signigicantly faster in RAW mode unless you want to proceed directly to playback.

File deletions on the K-3 still aren't performed in the background, and an unnecessary progress bar is shown for about a second whenever you delete a file.  This is the only real annoyance that we could find.

Continuous Shooting and Buffer

The K-3 has received an upgraded shutter mechanism that can shoot at a best-in-class 8.3 FPS.  Its durability has been doubled compared to that of the Pentax K-5, as it is rated for 200,000 actuations, up from 100,000.  This durability is best-in-class as of the writing of this review.

The K-3 now also supports UHS-I cards, meaning that it can write data much faster than its predecessors could.

The video below shows the K-3's high framerate.  You should also notice that the shutter sound has gotten even quieter compared to the K-5, which is great not only for bursts, but also for single shots.

And the video below shows the amount of time that in-camera lens corrections add during a continuous JPEG burst:

Pentax hasn't cut back on upgrading the K-3's buffer.  According to the specs, the K-3 can shoot up to 60 fine JPEG files, 100 standard JPEG files, or 200 basic JPEG files.  This is much higher than the K-5 II's 30-40 frames.

To find out just how big these improvements are in real life, we tested the K-3 and the K-5 IIs with the following memory cards:

• Card 1: SanDisk 95Mb/s 32GB Extreme Pro SDHC Class 10 UHS-I
• Card 2: SanDisk 45Mb/s 32GB Extreme SDHC Class 10 UHS-1

Both cards should be faster than the K-5 II's maximum write speed.  So, with the faster card, can the K-3 do better than the K-5 II?  See our results below!

We can thus conclude that the K-3 clearly has an advantage in terms of buffer size in JPEG mode, as even with the slower card, it was able to capture 10 more frames at maximum resolution and quality.  With the 95Mb/s card, it captured 52 frames, very close to the advertised 60. It is a bit disappointing that the K-3's RAW buffer is no bigger than that of the K-5, but at least it hasn't gotten smaller.  Note that in real life, variations in buffer size can occur based on what you're shooting, as photos with lots of dark shadows or blown highlights tend to be smaller.

But what if you want to shoot more than just 52 frames?  Well, even though the K-3 can only sustain its maximum framerate for a few seconds, it will continue chugging along at 2-3 FPS until the card is full.  We were able to get over 300 frames out of the K-3 in JPEG Fine mode and it didn't want to stop!  This was true for both cards that we tried.

If you don't have a high-speed card and you start shooting bursts with the K-3, you will find yourself having to wait much longer for its large files to finish writing compared to the K-5 II.  With a high-speed card, however, the K-3 performs almost just as well as the K-5 II: thus, it essentially makes up for its larger file size by being able to utilize faster memory cards.  We highly recommend that you pick up at least one SanDisk 95Mb/s 32GB Extreme Pro SDHC Class 10 UHS-I card for use with the K-3.

While the K-3 is writing files to its card, playback mode and the menu system are inaccessible for about 6 seconds (JPEG fine mode) or 15 seconds (RAW mode) after the last frame.  You can always enter live view mode or continue shooting through the viewfinder, however.

The USB3 connectivity that the K-3 supports will help ensure that files stored on high-speed memory cards will be downloaded quickly (i.e. above the 35Mb/s limit of USB2).

Live View Framerate

The K-3's live view has a refresh rate of 60 frames per second and has virtually no latency, which means that it is on par with what we've seen in the K-30/K-50 and better than what the K-5/K-5 II/K-5 IIs had to offer.  The live view image only gets a bit choppy in low ambient light.

The live view display tries to do its best to keep the image well-exposed.  It does not stop the lens down until you shoot or unless you use the camera's digital preview feature.

In order to allow for increased AF performance, focus peaking is disabled while the AF system is in operation.  Unlike on the K-50, however, the live view resolution does not decrease during AF, which is good to see.  The improved performance can be attributed to the K-3's faster processor.

Even though the K-3 does not exit live view if you change modes on the mode dial, the mirror does flip down whenever you try to access the info screen to make quick settings changes.  Live view is automatically re-enabled when you press the info button again, but this wastes power and means that returning to live view isn't instant.

Note that when Shake Reduction is enabled, the live view image is stabilizated.  This creates a bit of audible noise when using live view, but it isn't an annoyance unless you put your ear close to the camera.  Note that even with SR disabled, there will still be a slight noise as the camera needs to keep the SR magnets active to "lock" the sensor in place.

Desktop File Transfer

For those who don't have a fast SD card reader, or if you don't want to remove your memory cards from the camera, you can transfer files from the K-3 to your PC using a USB3 connection.  The Micro B USB3 cable must be purchased separately.  Once you connect the camera to your computer, power it on and it should appear as a mass storage device in your operating system.

The overall transfer speed will depend on both your memory card speed and your desktop's bus/drive speed.  With either of the memory cards we tested and typical PC hardware, you can expect a transfer speed of 30Mb/s or higher, assuming that your computer has a USB3 port.

We measured a file transfer rate of 30 Mb/s with a USB 3 cord and 19 Mb/s with a USB 2 cord.  Faster transfer speeds up to the card's maximum speed are possible via external card readers.

Battery Life

The K-3 takes the same D-Li90 batteries as the K-5 IIs, K-5 II, K-5, K-7, and 645D.  While using it in the field we did not observe it to be any more power-hungry than its predecessor.  If you wish to expand your camera's battery life, you can purchase the optional D-BG5 battery grip which can carry an additional battery or 6 AA's.  Without flash use, you can expect to be able to capture well over 1000 photos per charge per battery.

A nice feature of the K-3 (and earlier cameras) is its auto power-off setting.  By default, the camera will turn itself off after one minute of inactivity, so if you accidentally forget to turn it off, your battery won't be drained.  The auto power-off setting can also be disabled or set as high as 30 minutes.

Performance Verdict

The processor in the Pentax K-3 really packs a punch.  Overall, its performance is unquestionably state-of-the-art.  It does an excellent job of handling the K-3's larger files, and routine tasks such as processing lens corrections or entering live view have become faster.  Playback mode- even in 81-thumbnail view- display photos almost instantly.  If you pair the camera with a non-UHS-I card, however, you will find it to be a noticeable bottleneck in burst mode, and with a slow card, you'll continue to see the hourglass icon for a noticable period of time.  For the best burst performance, we recommend fast SDHC/SDXC cards such as the SanDisk 95Mb/s or 80Mb/s cards, or Lexar 1000x or 800x cards.  The great thing about the K-3 is that the number of shots you can take in burst mode is only limited by the size of your card as long as you can settle for a reduced framerate. The faster your card, however, the longer you can sustain the higher framerate and the faster the buffer will be flushed.  The only thing we hoped for but didn't get in the K-3 was a larger RAW buffer.

When using the K-3 in the field, it simply feels faster than the K-5 IIs as you'll spend less time looking at the hourglass icon and more time shooting and reviewing photos.  Pentax has really improved this camera's performance all-around.  Even more importantly, perhaps, the PRIME III processor also enables more reliable live view autofocus.  See the next page for details.