In summary
The Pentax K-3 III is compact, robustly-built, weather-resistant, and boasts an impressive array of controls. When coupled with a weather-resistant lens, it becomes a take-anywhere camera that will suit outdoors shooters and is compact enough for travel use.
It’s also a highly sophisticated camera, best suited to professional and advanced amateur photographers who are prepared to take the time to learn how to ‘drive’ it. With a menu that contains more than 200 individual settings – just for shooting stills – it’s not for basic hobbyists.
Full review
Announced at the end of March, 2021, the Pentax K-3 Mark III is the third edition in the flagship K-3 series of APS-C-format DSLR cameras. The new model may retain much of the physical styling of the six-year-old K3 II but internally it has been significantly redesigned. A new BSI-CMOS sensor with a resolution of approximately 26 megapixels and an AA (anti-aliasing)-filter-free optical design is coupled with the latest PRIME V imaging engine and new-generation accelerator unit greatly improving the noise-reduction performance.
Angled front view of the Pentax K-3 III with the Pentax DA 20-40mm f/2.8-4 ED Limited DC WR HD DA lens. (Source: Ricoh Imaging.)
The K3 Mark III is available in all-black and silver and black and also comes in a limited-edition Premium Silver version that includes the D-BG8 battery grip. It is not usually sold with a kit lens but we received the HD PENTAX-D FA 28-105mm f/3.5-5.6ED DC WR lens with the review camera. It is reviewed separately.
Who’s it For?
This is a highly sophisticated and very complicated camera that is best suited to professional and advanced amateur photographers who are prepared to take the time to learn how to ‘drive’ it. With a menu that contains more than 200 individual settings – just for shooting stills – it’s not for basic hobbyists.
Like its predecessor, the K-3 III’s compact, robustly-built camera body is weather-resistant and boasts an impressive array of controls. When coupled with a weather-resistant lens, it becomes a take-anywhere camera that will suit outdoors shooters and is compact enough for travel use.
The front, rear and top panels of the Pentax K-3 III. (Source: Ricoh Imaging.)
Unfortunately, the price of the camera body has roughly doubled since the K-3 II was released in late 2015, putting it out of the reach of cash-strapped photographers. It’s more expensive than similarly-featured APS-C DSLRs from other manufacturers but a bit cheaper than their full frame models.
Videographers and photographers who shoot a lot of video should give this camera miss, even though it’s capable of 4K 30p recording. Being tied to using Live View mode and the limited video options puts this camera well behind the current crop of mirrorless cameras, even some fairly basic models.
What’s New?
The new BSI-CMOS sensor provides a slight increase in resolution over the previous model, although it’s barely enough to signify in ‘big picture’ terms. The AA (anti-aliasing)-filter-free optical design carries over from the previous two models.
However, the improved PRIME V processor and new-generation accelerator unit in the pre-processor combine to improve detail retention and low-light noise reduction performance. The new camera can record images at sensitivities up to ISO 1,600,000 – up from ISO 512,000 in the K-3 II – although we found image quality at the highest settings left a lot to be desired.
One significant physical improvement is the new optical viewfinder, which covers almost 100% of the image frame and has a magnification of approximately 1.05x to provide better shot-framing capabilities. Featuring a new high-refraction glass prism, along with a distortion-correcting optical element and optimised lens coatings it has a generous 22 mm eye relief and the back end sticks out further to reduce the chance of your nose leaving grease on the monitor screen.
Ricoh claims it provides a wide field of view equivalent to that of a full-frame SLR plus a 10% increase in brightness over the OVF in the Pentax K-3. Other features include a Natural Bright Matte III focusing screen and a transparent display that lets the user monitor a wide range of operational data in the viewfinder window.
The resolution of the LCD monitor has increased slightly from 1,037,000 to 1,620,000 dots, although it remains a 3.2-inch. But it’s still non-articulating and its touch controls are largely unchanged, although the camera’s menus have been tweaked to make them easier to use via touch controls.
The K3 Mark III also features a new SAFOX 13 phase-matching AF sensor module with 101 focus sensors, 25 of which are cross-type sensors positioned mid-frame to provide faster, more accurate autofocusing. The system claims an ability to achieve pinpoint focus on subjects in light levels down to -4 EV.
Aided by a new, high-capacity RGBIr image sensor with approximately 307,000 pixels plus a newly developed image-tracking algorithm, the camera can also accurately track subjects moving with changing speeds or irregular directions. A new 8-way joystick AF point selector provides user selectable control over up to 41 focus points.
The new joystick control for focus positioning. (Source: Ricoh Imaging.)
The PRIME V processor includes an improved Real-time Scene Analysis System that offers face and eye selection using advanced image recognition technology plus real-time analysis of subject movement. This helps to optimise exposure settings as well as improving focus accuracy. Deep Learning AI technology further refines subject detection and scene analysis.
The in-body image stabilisation system has also been improved with a new, five-axis mechanism that claims up to 5.5 stops of shake correction with compatible lenses. It includes a new Panning mode for recording sharp images of slow-moving subjects, which can adjust the AF response if the Auto mode fails to detect deliberately slow pans.
The mirror and shutter mechanism have been reworked and the system uses a coreless motor to provide faster response times. The mirror mechanism is also lighter allowing the mirror to settle faster and reduce viewfinder blackout.
Continuous shooting speed has been increased from up to 8.3 fps in the K-3 II to 12 fps (or 11 fps with continuous AF) in the new camera. The shutter is CIPA rated for 300,000 cycles.
The proprietary Hyper Operation system features a new Advanced mode for more flexible exposure control plus an Operation Control Lock function for preventing accidental re-setting of exposure-setting buttons and the four-way controller. A dedicated Smart Function button allows speedy selection and setting of various functions without the need to use on-screen menus and 10 different control buttons are available for customisation.
Some changes have been made to the array of buttons down the left hand side of the lens mounting area. The X-sync port has been move up to near where the now-defunct GPS button used to be on the K-3 II. A new Shake Reduction button takes its place. The RAW and AF mode buttons and AF/MF switch remain largely unchanged.
There’s also been a bit of button shuffling on the rear panel to allow for the new joystick. This has seen the Green button move down a little, the Movie/LiveView/Stills selector move to the top panel, the playback button replace the red movie recording button and the removal of the change AF Point/Card slot switch button on the lower right hand corner. The flash button on the four-way controller has been replaced by an Outdoor View button that lets users switch to a brighter monitor screen.
Finally, 4K video recording has been added to the previous model’s FHD settings. But it’s limited to 30 or 24 fps. Full HD 1080p recording is available at 60p/30p/24p frame rates using the H-264 recording format. Interestingly, the K-3 III includes microphone and headphone jacks and supports stereo audio recording.
Instead of the now-defunct O-FC1 FluCard, updated communications functions include the now-standard low-energy Bluetooth and wireless LAN connections for linking the camera with smartphones and tablet computers. The proprietary Image Sync app lets users view images from the camera’s live view screen on a smartphone, adjust basic camera settings, transfer them to the mobile device and upload them to various SNS sites.
What Hasn’t Changed
Like its predecessor, the K-3 III’s exterior casing (top and bottom panels and front and back frames) is made from lightweight magnesium alloy and it has the same generous grip with rubberised cladding. Most of the physical controls are unchanged, although the mode dial on the top panel now has five Custom settings instead of three.
The Pixel Shift Resolution System is largely unchanged and still used to improve the quality of the image, rather than for increasing resolution. The camera must be tripod-mounted when this mode is used.
The three-dial system used in the K-3 II, which adds a separate function dial to the regular front and rear dials, also carries over from the previous model. In conjunction with an S.Fn button in front of the dial, it allows users to quickly access functions that are otherwise not selectable with the other dials. The S.Fn button lets users change which functions are assigned to the dial.
The K-3 III retains the dual SD card slots of its predecessor, with Slot One conforming to the UHS-II standard. It also uses the same D-LI90 rechargeable lithium-ion battery, although it is now rechargeable via a USB Type-C terminal. Consequently, a separate charger is not supplied with the camera.
Minor improvements have been made to the DR II (Dust Removal II) mechanism, which uses ultrasonic vibrations to dislodge dust and particulate matter from the sensor. The GPS and Astrotracer functions are largely unchanged.
Sensor and Image Processing
Despite the increase in resolution the image formats available are essentially the same as in the previous two models. Users can access four JPEG sizes, each with three compression ratios and also choose between the Pentax proprietary PEF and ‘open’ DNG raw file formats. RAW+JPEG recording is supported and the different file formats can be directed to separate SD cards.
Interestingly, JPEG compression ratios appear to be higher in the new camera, leading to smaller files. Typical image and file sizes at the three compression ratios are shown in the table below.
| Image size | Quality | *** | ** | * |
| 6192 x 4128 | RAW | 56.74MB | ||
| JPEG | 16.16MB | 7.14MB | 3.65MB | |
| 4752 x 3168 | JPEG | 9.56MB | 4.27MB | 2.22MB |
| 3648 x 2432 | JPEG | 5.71MB | 2.58MB | 1.37MB |
| 1920 x 1280 | JPEG | 1.70MB | 0.815MB | 0.49MB |
As before, photographers looking for the highest resolution from camera and lens will shoot with the AA filter simulator off (the default). But in situations where moiré patterns may occur, they can choose between the lighter and heavier anti-aliasing.
For video recording, the slight loss of resolution due to the AA filter simulation is immaterial as resolution is down-sampled by a huge amount to fit the image data into each frame. Video clips are recorded in the MPEG-4 AVC format with H.264 compression. The highest quality is 4K 30p and up to 4GB of video r 25 minutes of recording is the limit for each clip. Recording will also stop if the internal temperature of the camera gets too high.
Playback and Software
The K-3 III provides the same image playback settings as the K-3 II and includes the same effects filters and raw file conversion options (JPEG only). The same basic in-camera editing functions are provided for still images and movie clips.
No software was supplied with the review camera but you can download either the software or the user manuals from the Pentax Australia website, which links you to the head office in Japan, via this link.
There’s not much model-specific software for the new camera but both PEF and DNG files from the camera can be converted into editable TIFFs with the latest versions of Adobe Camera Raw, our preferred raw file processor.
Performance
Our Imatest tests and sample shots were recorded with the HD PENTAX-D FA 28-105mm f/3.5-5.6 ED DC WR lens, which was supplied with the review camera. The AA filter simulator was set on ‘Low’ and all filters and effects were disabled to minimise the influence of special processing.
The default sRGB colour space was re-set to Adobe RGB to record the maximum colour gamut and our test shots were recorded at the highest JPEG resolution and quality. Raw files were captured in the ‘universal’ DNG format.
We didn’t bother with PEF.RAW files since the results of our previous tests showed little or no difference in performance with the two available raw formats. Similarly, the Pixel Shift Resolution function was not tested since it hasn’t changed since the K3 Mark II and it didn’t make much difference to image resolution.
Imatest showed the review camera and lens were capable of delivering high resolution, although the best JPEG files fell a little short of expectations for the camera’s 24-megapixel sensor. Some raw files just exceeded expectations, but only mid-way out from the centre of the frame and for a few aperture settings with the shorter focal lengths.
Resolution tailed off steadily as sensitivity was increased, as shown in the graph of our test results across the camera’s sensitivity range below. There was a steep drop, especially for JPEGs with the two highest ISO settings, as shown in the graph of our Imatest results below.
Test shots at night confirmed our Imatest results, showing a noticeable increase in image noise and loss of sharpness from ISO 51200 on. Converted raw files were more noise-resistant then JPEGs, with noise becoming evident at ISO 102400 and DNG files recorded at ISO 204800 being usable at small output sizes and for certain applications.
Shots taken at the two highest sensitivity settings were effectively unusable, regardless of whether they were JPEGs or DNG raw files. We really can’t fathom why Ricoh pushed sensitivity to such a degree because the camera runs out of usable shutter speed and aperture combinations at the light levels that would justify their use.
Colour accuracy was generally quite good and there was a close correspondence between JPEG rendition and the reproduction of the colours in DNG.RAW files. In both cases, saturation was very restrained, although there were few actual colour shifts.
Auto white balance performance was similar to the K-3 Mark II’s and we couldn’t see any difference between shots taken with the AWB setting and those taken using the Multi Auto setting. Shots taken under both warm-toned LED and domestic fluorescent lighting showed no evidence of colour casts, while shots taken under incandescent lighting retained the characteristic orange cast.
The in-camera pre-sets went some way towards correcting colour biases and the camera provides plenty or adjustments for tweaking colour balance. Colour biases are also easily correctable with even basic image editors.
Autofocusing was generally fast and accurate for both still photography and in movie mode and, thanks to the increased number of focus points, the review camera had few problems focusing in very low light levels. We found the new joystick control made it much easier to position the focus measurement area, enabling a high degree of focusing accuracy under a wide range of conditions.
We carried out our timing tests with a 32GB SanDisk Ultra SDHC II U3 memory card in one slot and a 16GB Lexar Professional SDHC-I card in the other. Raw files were directed to the faster SanDisk card, with JPEGs going to the other card. The viewfinder was used for framing shots to minimise delays associated with Live View shooting.
The review camera took just under one second to power up but shut down instantaneously. We measured an average capture lag of 0.55 seconds, which is marginally faster than we found with the Mark II. When shots were pre-focused, this lag dropped to 0.2 seconds, due in part to a slow shutter button response.
JPEG files took roughly one second to process on average, going by the indicator light on the back of the camera. DNG.RAW files averaged 2.7 seconds and RAW+JPEG pairs averaged just under three seconds. Shot-to shot times averaged 0.5 seconds with the viewfinder, but roughly 2.3 seconds in Live View mode.
In the high-speed continuous shooting mode with focus and exposure locked on the first frame, the camera was able to record 63 frames in 15.3 seconds before the first pause. It took more than 30 seconds to clear the buffer memory.
With DNG.RAW files, the first hesitation occurred after 45 frames were recorded in 10.9 seconds. Processing was completed within 11.9 seconds of the last frame recorded. Similar figures were recorded for RAW+JPEG pairs, although the number of recorded files fell to 41 in 10 seconds. The processing time was reduced to 11.7 seconds.
Video performance was much as you’d expect from a DSLR camera but 4K footage is recorded with the frame cropped, whereas Full HD video uses the width of the frame. The camera’s built-in stabiliser doesn’t work in video mode, which means hand-held recordings can be shaky and unsharp, further complicating the AF system.
We found focusing speeds were seldom fast enough to keep track of moving subjects, and while touch focusing will allow for smooth focus transitions the camera must be kept rock steady. Tripod mounting is advisable.
Conclusion
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SPECS
Image sensor: 23 x 15.5 mm BSI-CMOS sensor with 26.78 million photosites (25.73 megapixels effective); no AA filter
Image processor: PRIME V
Lens mount: Pentax KAF2 bayonet mount
Focal length crop factor: 1.5x
Image formats: Stills: JPEG (Exif Ver. 2.3), PEF/DNG.RAW (14-bit), RAW+JPEG; Movies: MPEG-4 AVC/ H.264 (MOV)
Audio: Linear PCM
Image Sizes: Stills: 6192 x 4128, 4752 x 3168, 3648 x 2432, 1920 x 1280 Movies: 4K (3840 x 2160) at 30/25/24p, 1920 x 1080 at 60/50/30/25/24p
Aspect ratios: 4:3, 3:2, 16:9, 1:1
Image Stabilisation: 5-axis sensor-shift IBIS; 5.5 stops of shake correction (CIPA rating)
Dust removal: Ultrasonic vibration
Shutter (speed range): Electronically-controlled focal plane shutter (30-1/8000 seconds plus Bulb (1 sec. to 20 min.); Electronic shutter is used for Pixel Shift Resolution
Exposure Compensation: +/- 5EV in 1/3 and 1/2EV steps (+/-EV for movies)
Exposure bracketing: +/- 5EV across 2, 3, 5 frames in 1/3 EV, 1/2 EV steps
Other bracketing options: White balance, motion, depth of field
Self-timer: or seconds delay plus
Interval recording: Yes, for time-lapse
Focus system: SAFOX 13 TTL phase-matching detection system with 101 points (25 cross-type), EV -4 to 18
AF selection: Multi-area, Centre, Selective single-point, Tracking, Single, Continuous, Touch, Face Detection, Live View (contrast AF)
Focus modes: AFS (Single) / AFC (Continuous) / MF
Exposure metering: TTL open-aperture sensing system using 307,000 pixel RGB-lr sensor with Multi-segment, Centre-weighted, Highlight-weighted and Spot metering patterns; range -3EV to 20EV
Shooting modes: Scene-analyse Auto, Program AE, Sensitivity Priority AE, Aperture Priority AE, Shutter Priority AE, shutter & Aperture Priority AE, Manual Exposure plus 4 User-programmable modes
Custom modes: Auto Select, Bright, Natural, Portrait, Landscape, Vibrant, Radiant, Muted, Flat, Bleach Bypass, Reversal Film, Monotone, Cross Processing (7 settings)
Filter modes: Extract Colour, Replace Colour, Retro, High Contrast, Invert Colour, Unicolour Bold, Bold Monochrome
Colour space options: sRGB and Adobe RGB
ISO range: Auto, ISO 100-1600000
White balance: Auto, Multi Auto, Daylight, Cloudy, Shade, Incandescent, Fluorescent (x4), Manual (x 3), Colour temperature setting (x 3); +/-14 steps of adjustment A-B and G-M
Flash: External flashguns only
Flash modes: Auto, Auto + Red-eye Reduction, Flash On, Flash On + Red-eye Reduction, Slow- speed Sync, Slow-speed Sync + Red-eye, P-TTL, Contrast-control-sync, High-speed sync, Wireless sync
Flash exposure adjustment: -2 to +1 EV
Sequence shooting: Max. 12 frames/sec. with locked AF
Buffer capacity: Max. 37 Large/Fine JPEGs, 32 RAW files
Storage Media: Dual SD, SDHC, SDXC slots (UHS-II supported in Slot 1)
Viewfinder: Pentaprism with 100% frame coverage, 1.05x magnification, 22 mm eye relief, -4 to +1 dpt adjustment, Natural-Bright-Matte focusing screen
LCD monitor: Fixed 3.2-inch TFT LCD touch-screen (capacitance type) with 1,620,000 dots, brightness adjustable, night vision display
Interface terminals: USB 3.2 Gen 1 (5 GBit/sec), micro HDMI, microphone and headphone ports, 2.5mm cable release terminal, X-sync socket
Wi-Fi function: Built-in Wi-Fi (IEEE 802.11b/g/n) ; Bluetooth v4.2 (Bluetooth Low Energy)
Power supply: D-LI90 rechargeable Li-ion battery; CIPA rated for approx. 800 shots/charge with monitor, shots/charge with EVF
Dimensions (wxhxd): Approx. 134.5 x 103.5 x 73.5 mm (excluding protrusions)
Weight: Approx. 820 grams with battery and card
Distributor: C.R. Kennedy & Company, (03) 9823 1555
TESTS
Based on JPEG image files taken with the HD PENTAX-D FA 28-105mm f/3.5-5.6 ED DC WR lens.
Based on DNG.RAW image files recorded simultaneously and converted into 16-bit TIFF format with Adobe Camera Raw.
SAMPLES
All test images were captured with the HD PENTAX-D FA 28-105mm f/3.5-5.6 ED DC WR lens.
Auto white balance with incandescent lighting.
Auto white balance with fluorescent lighting.
Auto white balance with warm-toned LED lighting.
30-second exposure at ISO 100 at f/4, 37mm focal length.
20-second exposure at ISO 800 at f/5, 37mm focal length.
8-second exposure at ISO 6400 at f/7.1, 37mm focal length.
6-second exposure at ISO 25600 at f/9, 37mm focal length.
4-second exposure at ISO 51200 at f/11, 37mm focal length.
1.6-second exposure at ISO 102400 at f/14, 37mm focal length.
1-second exposure at ISO 204800 at f/16, 37mm focal length.
0.6-second exposure at ISO 409600 at f/16, 37mm focal length.
1/10-second exposure at ISO 1600000 at f/22, 37mm focal length.
Example of wide dynamic range: 28mm focal length, ISO 100, 1/800 second at f/9.
Close-up; 28mm focal length at ISO 100, 1/125 second at f/3.5.
Close-up; 105mm focal length at ISO 100, 1/125 second at f/5.6.
68mm focal length, ISO 200, 1/60 second at f/4.5.
28mm focal length, ISO 25600, 1/1000 second at f/8.
72mm focal length, ISO 200, 1/60 second at f/4.5.
Still frame from 4K movie clip recorded at 30p.
Still frame from 4K movie clip recorded at 24p.
Still frame from Full HD movie clip recorded at 60p.
Still frame from Full HD movie clip recorded at 24p.
Additional image samples can be found with our review of the HD PENTAX-D FA 28-105mm f/3.5-5.6 ED DC WR lens.
Rating
RRP: AU$2799 (body only); US$1999.95 (body only)
- Build: 9.0
- Features: 8.9
- Ease of use: 8.0
- Autofocusing: 8.6
- Still image quality JPEG: 8.6
- Still image quality RAW: 8.9
- Video quality: 8.3
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