Pentax K-3 II vs Sony A900
The Pentax K-3 II and the Sony Alpha A900 are two digital cameras that were officially introduced, respectively, in April 2015 and September 2008. Both are DSLR (Digital Single Lens Reflex) cameras that are based on an APS-C (K-3 II) and a full frame (A900) sensor. The Pentax has a resolution of 24.1 megapixels, whereas the Sony provides 24.4 MP.
Below is an overview of the main specs of the two cameras as a starting point for the comparison.
Going beyond this snapshot of core features and characteristics, what are the differences between the Pentax K-3 II and the Sony Alpha A900? Which one should you buy? Read on to find out how these two cameras compare with respect to their body size, their imaging sensors, their shooting features, their input-output connections, and their reception by expert reviewers.
The physical size and weight of the Pentax K-3 II and the Sony A900 are illustrated in the side-by-side display below. The two cameras are presented according to their relative size. Three consecutive perspectives from the front, the top, and the back are available. All width, height and depth dimensions are rounded to the nearest millimeter.
The K-3 II can be obtained in two different colors (black, silver), while the A900 is only available in black.
If the front view area (width x height) of the cameras is taken as an aggregate measure of their size, the Sony A900 is notably larger (39 percent) than the Pentax K-3 II. Moreover, the A900 is markedly heavier (12 percent) than the K-3 II. In this context, it is worth noting that both cameras are splash and dust-proof and can, hence, be used in inclement weather conditions or harsh environments.
The above size and weight comparisons are to some extent incomplete since they do not consider the interchangeable lenses that both of these cameras require. Hence, you might want to study and compare the specifications of available lenses in order to get the full picture of the size and weight of the two camera systems.
The following table provides a synthesis of the main physical specifications of the two cameras and other similar ones. In case you want to display and compare another camera duo, you can use the CAM-parator app to select your camera combination among a large number of options.
|1.||Pentax K-3 II||131 mm||100 mm||77 mm||800 g||720||Y||Apr 2015||1,099|
|2.||Sony A900||156 mm||117 mm||82 mm||895 g||880||Y||Sep 2008||2,999|
|3.||Canon 80D||139 mm||105 mm||79 mm||730 g||960||Y||Feb 2016||1,199|
|4.||Canon 5D Mark II||152 mm||114 mm||75 mm||850 g||850||Y||Sep 2008||3,499|
|5.||Nikon D7200||136 mm||107 mm||76 mm||765 g||1110||Y||Mar 2015||1,199|
|6.||Panasonic S1||149 mm||110 mm||97 mm||1017 g||400||Y||Feb 2019||2,499|
|7.||Panasonic GX8||133 mm||78 mm||63 mm||487 g||330||Y||Jul 2015||1,199|
|8.||Pentax K-3 III||135 mm||104 mm||74 mm||820 g||800||Y||Mar 2021||1,999|
|9.||Pentax KP||132 mm||101 mm||76 mm||703 g||390||Y||Jan 2017||1,099|
|10.||Pentax K-70||126 mm||93 mm||74 mm||688 g||410||Y||Jun 2016||649|
|11.||Pentax K-S2||123 mm||91 mm||73 mm||678 g||410||Y||Feb 2015||749|
|12.||Pentax K-3||131 mm||100 mm||77 mm||800 g||560||Y||Oct 2013||1,299|
|13.||Pentax K-5 II||131 mm||97 mm||73 mm||760 g||740||Y||Sep 2012||1,099|
|14.||Pentax K-5||131 mm||97 mm||73 mm||760 g||740||Y||Sep 2010||1,099|
|15.||Sony A99 II||143 mm||104 mm||76 mm||849 g||490||Y||Sep 2016||3,199|
|16.||Sony A99||147 mm||111 mm||78 mm||812 g||500||Y||Sep 2012||2,799|
|17.||Sony A850||156 mm||117 mm||82 mm||895 g||880||Y||Aug 2009||1,999|
|Notes: Measurements and pricing do not include easily detachable parts, such as add-on or interchangeable lenses or optional viewfinders.|
The price is, of course, an important factor in any camera decision. The manufacturer’s suggested retail prices give an idea on the placement of the camera in the maker’s lineup and the broader market. The K-3 II was launched at a markedly lower price (by 63 percent) than the A900, which puts it into a different market segment. Usually, retail prices stay at first close to the launch price, but after several months, discounts become available. Later in the product cycle and, in particular, when the replacement model is about to appear, further discounting and stock clearance sales often push the camera price considerably down. Then, after the new model is out, very good deals can frequently be found on the pre-owned market.
The size of the sensor inside a digital camera is one of the key determinants of image quality. A large sensor will tend to have larger individual pixels that provide better low-light sensitivity, wider dynamic range, and richer color-depth than smaller pixel-units in a sensor of the same technological generation. Moreover, a large sensor camera will give the photographer more control over depth-of-field in the image and, thus, the ability to better isolate a subject from the background. On the downside, larger sensors are more costly to manufacture and tend to lead to bigger and heavier cameras and lenses.
Of the two cameras under consideration, the Pentax K-3 II features an APS-C sensor and the Sony A900 a full frame sensor. The sensor area in the A900 is 135 percent bigger. As a result of these sensor size differences, the cameras have a format factor of, respectively, 1.5 and 1.0. Both cameras have a native aspect ratio (sensor width to sensor height) of 3:2.
With 24.4MP, the A900 offers a higher resolution than the K-3 II (24.1MP), but the A900 nevertheless has larger individual pixels (pixel pitch of 5.94μm versus 3.90μm for the K-3 II) due to its larger sensor. However, the K-3 II is a much more recent model (by 6 years and 7 months) than the A900, and its sensor will have benefitted from technological advances during this time that enhance the light gathering capacity of its pixel-units. Coming back to sensor resolution, it should be mentioned that the K-3 II has no anti-alias filter installed, so that it can capture all the detail its sensor resolves.
Unlike the A900, the K-3 II has the capacity to capture high quality composite images by combining multiple shots after shifting its sensor by miniscule distances. This multi-shot, pixel-shift mode is most suitable for photography of stationary objects (landscapes, studio scenes).
The Pentax K-3 II has a native sensitivity range from ISO 100 to ISO 51200. The corresponding ISO settings for the Sony Alpha A900 are ISO 200 to ISO 3200, with the possibility to increase the ISO range to 100-6400.
Consistent information on actual sensor performance is available from DXO Mark for many cameras. This service assesses and scores the color depth ("DXO Portrait"), dynamic range ("DXO Landscape"), and low-light sensitivity ("DXO Sports") of camera sensors, and also publishes an overall camera score. The Overall DXO ratings for the two cameras under consideration are close, suggesting that they provide similar imaging performance. The following table provides an overview of the physical sensor characteristics, as well as the sensor quality measurements for a selection of comparators.
|1.||Pentax K-3 II||APS-C||24.1||6016||4000||1080/60i||23.6||13.6||1106||80|
|2.||Sony A900||Full Frame||24.4||6048||4032||none||23.7||12.3||1431||79|
|4.||Canon 5D Mark II||Full Frame||21.0||5616||3744||1080/30p||23.7||11.9||1815||79|
|6.||Panasonic S1||Full Frame||24.0||6000||4000||4K/60p||25.2||14.5||3333||95|
|7.||Panasonic GX8||Four Thirds||20.2||5184||3888||4K/30p||23.5||12.6||806||75|
|8.||Pentax K-3 III||APS-C||25.6||6192||4128||4K/30p||..||..||..||..|
|13.||Pentax K-5 II||APS-C||16.1||4928||3264||1080/25p||23.8||14.1||1235||82|
|15.||Sony A99 II||Full Frame||42.2||7952||5304||4K/30p||25.4||13.4||2317||92|
|16.||Sony A99||Full Frame||24.0||6000||4000||1080/60p||25.0||14.0||1555||89|
|17.||Sony A850||Full Frame||24.4||6048||4032||none||23.8||12.2||1415||79|
Many modern cameras are not only capable of taking still images, but also of capturing video footage. The K-3 II indeed provides movie recording capabilities, while the A900 does not. The highest resolution format that the K-3 II can use is 1080/60i.
Apart from body and sensor, cameras can and do differ across a variety of features. The K-3 II and the A900 are similar in the sense that both have an optical viewfinder. The latter is useful for getting a clear image for framing even in brightly lit environments. The viewfinders of both cameras offer the same field of view (100%), but the viewfinder of the A900 has a higher magnification than the one of the K-3 II (0.74x vs 0.63x), so that the size of the image transmitted appears closer to the size seen with the naked human eye. The adjacent table lists some of the other core features of the Pentax K-3 II and Sony A900 along with similar information for a selection of comparators.
|1.||Pentax K-3 II||optical||Y||3.2 / 1037||fixed||n||1/8000s||8.3||n||Y|
|2.||Sony A900||optical||Y||3.0 / 922||fixed||n||1/8000s||5.0||n||Y|
|3.||Canon 80D||optical||Y||3.0 / 1040||swivel||Y||1/8000s||7.0||Y||n|
|4.||Canon 5D Mark II||optical||Y||3.0 / 920||fixed||n||1/8000s||3.9||n||n|
|5.||Nikon D7200||optical||Y||3.2 / 1229||fixed||n||1/8000s||6.0||Y||n|
|6.||Panasonic S1||5760||Y||3.2 / 2100||full-flex||Y||1/8000s||9.0||n||Y|
|7.||Panasonic GX8||2360||n||3.0 / 1040||swivel||Y||1/8000s||10.0||n||Y|
|8.||Pentax K-3 III||optical||Y||3.2 / 1620||fixed||Y||1/8000s||12.0||n||Y|
|9.||Pentax KP||optical||n||3.0 / 921||tilting||n||1/6000s||7.0||Y||Y|
|10.||Pentax K-70||optical||n||3.0 / 921||swivel||n||1/6000s||6.0||Y||Y|
|11.||Pentax K-S2||optical||n||3.0 / 921||swivel||n||1/6000s||5.4||Y||Y|
|12.||Pentax K-3||optical||Y||3.2 / 1037||fixed||n||1/8000s||8.3||Y||Y|
|13.||Pentax K-5 II||optical||Y||3.0 / 921||fixed||n||1/8000s||7.0||Y||Y|
|14.||Pentax K-5||optical||Y||3.0 / 921||fixed||n||1/8000s||7.0||Y||Y|
|15.||Sony A99 II||2400||Y||3.0 / 1229||full-flex||n||1/8000s||12.0||n||Y|
|16.||Sony A99||2359||Y||3.0 / 1229||full-flex||n||1/8000s||6.0||n||Y|
|17.||Sony A850||optical||Y||3.0 / 922||fixed||n||1/8000s||3.0||n||Y|
The Pentax K-3 II has an intervalometer built-in. This enables the photographer to capture time lapse sequences, such as flower blooming, a sunset or moon rise, without purchasing an external camera trigger and related software.
The K-3 II writes its imaging data to SDXC cards, while the A900 uses Compact Flash or Memory Stick PRO Duo cards. Both cameras feature dual card slots, which can be very useful in case a memory card fails.
For some imaging applications, the extent to which a camera can communicate with its environment can be an important aspect in the camera decision process. The table below provides an overview of the connectivity of the Pentax K-3 II and Sony Alpha A900 and, in particular, the interfaces the cameras (and selected comparators) provide for accessory control and data transfer.
Mic / Speaker
|1.||Pentax K-3 II||Y||mono / mono||Y||Y||mini||3.0||-||-||-|
|2.||Sony A900||Y||- / -||-||-||mini||2.0||-||-||-|
|3.||Canon 80D||Y||stereo / mono||Y||Y||mini||2.0||Y||Y||-|
|4.||Canon 5D Mark II||Y||mono / mono||Y||-||mini||2.0||-||-||-|
|5.||Nikon D7200||Y||stereo / mono||Y||Y||mini||2.0||Y||Y||-|
|6.||Panasonic S1||Y||stereo / mono||Y||Y||full||3.1||Y||-||Y|
|7.||Panasonic GX8||Y||stereo / mono||Y||-||micro||2.0||Y||Y||-|
|8.||Pentax K-3 III||Y||stereo / mono||Y||Y||micro||3.2||Y||-||Y|
|9.||Pentax KP||Y||stereo / mono||Y||-||-||2.0||Y||-||-|
|10.||Pentax K-70||Y||stereo / mono||Y||-||mini||2.0||Y||-||-|
|11.||Pentax K-S2||Y||mono / mono||Y||-||micro||2.0||Y||Y||-|
|12.||Pentax K-3||Y||mono / mono||Y||Y||mini||3.0||-||-||-|
|13.||Pentax K-5 II||Y||stereo / mono||Y||-||mini||2.0||-||-||-|
|14.||Pentax K-5||Y||stereo / mono||Y||-||mini||2.0||-||-||-|
|15.||Sony A99 II||Y||stereo / mono||Y||Y||micro||2.0||Y||Y||Y|
|16.||Sony A99||Y||stereo / mono||Y||Y||mini||2.0||-||-||-|
|17.||Sony A850||Y||- / -||-||-||mini||2.0||-||-||-|
Both cameras feature a PC Sync terminal to control professional strobe lights, which will be appreciated by studio photographers.
Travel and landscape photographers will find it useful that the K-3 II has an internal geolocalization sensor and can record GPS coordinates in its EXIF data.
Both the K-3 II and the A900 have been discontinued, but can regularly be found used on eBay. The A900 was replaced by the Sony A99, while the K-3 II was followed by the Pentax K-3 III. Further information on the two cameras (e.g. user guides, manuals), as well as related accessories, can be found on the official Pentax and Sony websites.
So what is the bottom line? Which of the two cameras – the Pentax K-3 II or the Sony A900 – has the upper hand? Is one clearly better than the other? A synthesis of the relative strong points of each of the models is listed below.
Arguments in favor of the Pentax K-3 II:
- Maximized detail: Lacks an anti-alias filter to exploit the sensor's full resolution potential.
- High quality composites: Can combine several shots after pixel-shifting its sensor.
- More dynamic range: Captures a larger spectrum of light and dark details (1.3 EV of extra DR).
- Broader imaging potential: Can record not only still images but also 1080/60i movies.
- Larger screen: Has a bigger rear LCD (3.2" vs 3.0") for image review and settings control.
- More detailed LCD: Has a higher resolution rear screen (1037k vs 922k dots).
- Faster burst: Shoots at higher frequency (8.3 vs 5 flaps/sec) to capture the decisive moment.
- Easier time-lapse photography: Has an intervalometer built-in for low frequency shooting.
- More compact: Is smaller (131x100mm vs 156x117mm) and thus needs less room in the bag.
- Less heavy: Is lighter (by 95g or 11 percent) and hence easier to carry around.
- Easier geotagging: Features an internal GPS sensor to log localization data.
- Faster data transfer: Supports a more advanced USB protocol (3.0 vs 2.0).
- More affordable: Was introduced into a lower priced category (63 percent cheaper at launch).
- More modern: Reflects 6 years and 7 months of technical progress since the A900 launch.
Advantages of the Sony Alpha A900:
- Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
- Better low-light sensitivity: Can shoot in dim conditions (0.4 stops ISO advantage).
- Larger viewfinder image: Features a viewfinder with a higher magnification (0.74x vs 0.63x).
- Longer lasting: Gets more shots (880 versus 720) out of a single battery charge.
- More heavily discounted: Has been around for much longer (launched in September 2008).
If the count of individual advantages (bullet points above) is taken as a guide, the K-3 II is the clear winner of the match-up (14 : 5 points). However, the pertinence of the various camera strengths will differ across photographers, so that you might want to weigh individual camera traits according to their importance for your own imaging needs before making a camera decision. A professional wedding photographer will view the differences between cameras in a way that diverges from the perspective of a travel photog, and a person interested in cityscapes has distinct needs from a macro shooter. Hence, the decision which camera is best and worth buying is often a very personal one.
How about other alternatives? Do the specifications of the Pentax K-3 II and the Sony A900 place the cameras among the top in their class? Find out in the latest Best DSLR Camera listing whether the two cameras rank among the cream of the crop.
In any case, while the comparison of the spec-sheets of cameras can offer a general idea of their imaging potential, it says little about, for example, the shooting experience and imaging performance of the K-3 II and the A900 in practical situations. User reviews, such as those found at amazon, can sometimes inform about these issues, but such feedback is often incomplete, inconsistent, and biased.
This is why expert reviews are important. The table below provides a synthesis of the camera assessments of some of the best known photo-gear review sites (amateurphotographer [AP], cameralabs [CL], digitalcameraworld [DCW], dpreview [DPR], ephotozine [EPZ], photographyblog [PB]). As can be seen, the professional reviewers agree in many cases on the quality of different cameras, but sometimes their assessments diverge, reinforcing the earlier point that a camera decision is often a very personal choice.
|1.||Pentax K-3 II||4.5/5||..||..||..||5/5||5/5||Apr 2015||1,099|
|2.||Sony A900||..||+ +||..||+ +||4.5/5||5/5||Sep 2008||2,999|
|3.||Canon 80D||4/5||+ +||4.5/5||84/100||4.5/5||4.5/5||Feb 2016||1,199|
|4.||Canon 5D Mark II||4/5||91/100||..||79/100||4/5||..||Sep 2008||3,499|
|5.||Nikon D7200||4/5||+ +||..||84/100||4.5/5||4.5/5||Mar 2015||1,199|
|6.||Panasonic S1||4.5/5||+ +||4.5/5||88/100||4.5/5||4/5||Feb 2019||2,499|
|7.||Panasonic GX8||5/5||+||..||82/100||4.5/5||4.5/5||Jul 2015||1,199|
|8.||Pentax K-3 III||..||..||..||..||..||..||Mar 2021||1,999|
|9.||Pentax KP||4/5||..||3/5||82/100||5/5||4.5/5||Jan 2017||1,099|
|10.||Pentax K-70||4.5/5||..||..||79/100||4.5/5||4.5/5||Jun 2016||649|
|11.||Pentax K-S2||4.5/5||..||..||..||5/5||4.5/5||Feb 2015||749|
|12.||Pentax K-3||4/5||..||..||83/100||5/5||5/5||Oct 2013||1,299|
|13.||Pentax K-5 II||5/5||..||..||80/100||5/5||4.5/5||Sep 2012||1,099|
|14.||Pentax K-5||4/5||..||..||83/100||5/5||4.5/5||Sep 2010||1,099|
|15.||Sony A99 II||..||..||4.5/5||85/100||4.5/5||4.5/5||Sep 2016||3,199|
|16.||Sony A99||5/5||..||..||84/100||4.5/5||4.5/5||Sep 2012||2,799|
|17.||Sony A850||3/5||..||..||75/100||..||4.5/5||Aug 2009||1,999|
|Notes: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.|
The above review scores should be interpreted with care, though. The ratings are only valid when referring to cameras in the same category and of the same age. A score, therefore, has to be seen in close connection to the price and market introduction time of the camera, and comparisons of ratings among very different cameras or across long time periods have little meaning. It should also be noted that some of the review sites have over time altered the way they render their verdicts.
Other camera comparisons
Did this review help to inform your camera decision process? In case you are interested in seeing how other cameras pair up, just make your choice using the following search menu. As an alternative, you can also directly jump to any one of the listed comparisons that were previously generated by the CAM-parator tool.
- Canon 1D Mark II vs Sony A900
- Canon 5D vs Sony A900
- Canon G7 X vs Pentax K-3 II
- Canon XS vs Pentax K-3 II
- Fujifilm X-H1 vs Pentax K-3 II
- Fujifilm XP120 vs Sony A900
- Olympus E-30 vs Sony A900
- Olympus E-510 vs Pentax K-3 II
- Olympus E-PL6 vs Sony A900
- Panasonic G85 vs Pentax K-3 II
- Panasonic LX10 vs Pentax K-3 II
- Sony A900 vs Sony HX400V
Specifications: Pentax K-3 II vs Sony A900
Below is a side-by-side comparison of the specs of the two cameras to facilitate a quick review of their differences and common features.
|Camera Model||Pentax K-3 II||Sony A900|
|Camera Type||Digital single lens reflex||Digital single lens reflex|
|Camera Lens||Pentax K mount lenses||Sony A mount lenses|
|Launch Date||April 2015||September 2008|
|Launch Price||USD 1,099||USD 2,999|
|Sensor Specs||Pentax K-3 II||Sony A900|
|Sensor Format||APS-C Sensor||Full Frame Sensor|
|Sensor Size||23.5 x 15.6 mm||35.9 x 24.0 mm|
|Sensor Area||366.6 mm2||861.6 mm2|
|Sensor Diagonal||28.2 mm||43.2 mm|
|Sensor Resolution||24.1 Megapixels||24.4 Megapixels|
|Image Resolution||6016 x 4000 pixels||6048 x 4032 pixels|
|Pixel Pitch||3.90 μm||5.94 μm|
|Pixel Density||6.56 MP/cm2||2.83 MP/cm2|
|Moiré control||no AA filter||Anti-Alias filter|
|Movie Capability||1080/60i Video||no Video|
|ISO Setting||100 - 51,200 ISO||200 - 3,200 ISO|
|ISO Boost||no Enhancement||100 - 6,400 ISO|
|Image Processor||PRIME III||BIONZ|
|DXO Sensor Quality (score)||80||79|
|DXO Color Depth (bits)||23.6||23.7|
|DXO Dynamic Range (EV)||13.6||12.3|
|DXO Low Light (ISO)||1106||1431|
|Screen Specs||Pentax K-3 II||Sony A900|
|Viewfinder Type||Optical viewfinder||Optical viewfinder|
|Viewfinder Field of View||100%||100%|
|Top-Level Screen||Control Panel||Control Panel|
|LCD Framing||Live View|
|Rear LCD Size||3.2inch||3.0inch|
|LCD Resolution||1037k dots||922k dots|
|LCD Attachment||Fixed screen||Fixed screen|
|Shooting Specs||Pentax K-3 II||Sony A900|
|Focus System||Phase-detect AF||Phase-detect AF|
|Manual Focusing Aid||Focus Peaking||no Peaking Feature|
|Continuous Shooting||8.3 shutter flaps/s||5 shutter flaps/s|
|Time-Lapse Photography||Intervalometer built-in||no Intervalometer|
|Image Stabilization||In-body stabilization||In-body stabilization|
|Fill Flash||no On-Board Flash||no On-Board Flash|
|Storage Medium||SDXC cards||CF or MS cards|
|Second Storage Option||Dual card slots||Dual card slots|
|Connectivity Specs||Pentax K-3 II||Sony A900|
|Studio Flash||PC Sync socket||PC Sync socket|
|USB Connector||USB 3.0||USB 2.0|
|HDMI Port||mini HDMI||mini HDMI|
|Microphone Port||External MIC port||no MIC socket|
|Headphone Socket||Headphone port||no Headphone port|
|Wifi Support||no Wifi||no Wifi|
|Geotagging||GPS built-in||no internal GPS|
|Body Specs||Pentax K-3 II||Sony A900|
|Environmental Sealing||Weathersealed body||Weathersealed body|
|Battery Life (CIPA)||720 shots per charge||880 shots per charge|
131 x 100 x 77 mm
(5.2 x 3.9 x 3.0 in)
156 x 117 x 82 mm
(6.1 x 4.6 x 3.2 in)
|Camera Weight||800 g (28.2 oz)||895 g (31.6 oz)|
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