Pentax K-3 vs Sony A900
The Pentax K-3 and the Sony Alpha A900 are two digital cameras that were announced, respectively, in October 2013 and September 2008. Both are DSLR (Digital Single Lens Reflex) cameras that are based on an APS-C (K-3) 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 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 side-by-side display below illustrates the physical size and weight of the Pentax K-3 and the Sony A900. 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 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. Moreover, the A900 is markedly heavier (12 percent) than the K-3. 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 table below summarizes the key physical specs of the two cameras alongside a broader set of comparators. If you would like to visualize and compare a different camera combination, you can navigate to the CAM-parator app and make your selection from a broad list of cameras there.
|1.||Pentax K-3||131 mm||100 mm||77 mm||800 g||560||Y||Oct 2013||1,299|
|2.||Sony A900||156 mm||117 mm||82 mm||895 g||880||Y||Sep 2008||2,999|
|3.||Nikon D7100||136 mm||107 mm||76 mm||765 g||950||Y||Feb 2013||1,199|
|4.||Pentax KP||132 mm||101 mm||76 mm||703 g||390||Y||Jan 2017||1,099|
|5.||Pentax K-70||126 mm||93 mm||74 mm||688 g||410||Y||Jun 2016||649|
|6.||Pentax K-S2||123 mm||91 mm||73 mm||678 g||410||Y||Feb 2015||749|
|7.||Pentax K-3 II||131 mm||100 mm||77 mm||800 g||720||Y||Apr 2015||1,099|
|8.||Pentax K-S1||121 mm||93 mm||70 mm||558 g||410||n||Aug 2014||749|
|9.||Pentax K-50||130 mm||97 mm||71 mm||650 g||410||Y||Jun 2013||599|
|10.||Pentax K-5 II||131 mm||97 mm||73 mm||760 g||740||Y||Sep 2012||1,099|
|11.||Pentax K-5||131 mm||97 mm||73 mm||760 g||740||Y||Sep 2010||1,099|
|12.||Sony A9||127 mm||96 mm||63 mm||673 g||650||Y||Apr 2017||4,499|
|13.||Sony A99 II||143 mm||104 mm||76 mm||849 g||490||Y||Sep 2016||3,199|
|14.||Sony A7S II||127 mm||96 mm||60 mm||627 g||370||Y||Sep 2015||2,999|
|15.||Sony A99||147 mm||111 mm||78 mm||812 g||500||Y||Sep 2012||2,799|
|16.||Sony A77||143 mm||104 mm||81 mm||732 g||470||Y||Aug 2011||1,399|
|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.|
Any camera decision will obviously take relative prices into account. The retail prices at the time of the camera’s release place the model in the market relative to other models in the producer’s line-up and the competition. The K-3 was launched at a markedly lower price (by 57 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 imaging sensor is a crucial determinant of image quality. A large sensor will generally have larger individual pixels that offer better low-light sensitivity, provide wider dynamic range, and have richer color-depth than smaller pixels 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 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.
Technology-wise, both cameras are equipped with CMOS (Complementary Metal–Oxide–Semiconductor) sensors.
With 24.4MP, the A900 offers a higher resolution than the K-3 (24.1MP), but the A900 nevertheless has larger individual pixels (pixel pitch of 5.94μm versus 3.90μm for the K-3) due to its larger sensor. However, the K-3 is a much more recent model (by 5 years) 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 has no anti-alias filter installed, so that it can capture all the detail its sensor resolves.
The Pentax K-3 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.
For many cameras, data on sensor performance has been reported by DXO Mark. This service is based on lab testing and assigns an overall score to each camera sensor, as well as ratings for dynamic range ("DXO Landscape"), color depth ("DXO Portrait"), and low-light sensitivity ("DXO Sports"). The Overall DXO ratings for the two cameras under consideration are close, suggesting that they provide similar imaging performance. The table below summarizes the physical sensor characteristics and sensor quality findings and compares them across a set of similar cameras.
| DXO |
|2.||Sony A900||Full Frame||24.4||6048||4032||none||23.7||12.3||1431||79|
|7.||Pentax K-3 II||APS-C||24.1||6016||4000||1080/60i||23.6||13.6||1106||80|
|10.||Pentax K-5 II||APS-C||16.1||4928||3264||1080/25p||23.8||14.1||1235||82|
|12.||Sony A9||Full Frame||24.0||6000||4000||4K/30p||24.9||13.3||3517||92|
|13.||Sony A99 II||Full Frame||42.2||7952||5304||4K/30p||25.4||13.4||2317||92|
|14.||Sony A7S II||Full Frame||12.0||4240||2832||4K/30p||23.6||13.3||2993||85|
|15.||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 can also record movies. The K-3 indeed provides movie recording capabilities, while the A900 does not. The highest resolution format that the K-3 can use is 1080/60i.
Apart from body and sensor, cameras can and do differ across a variety of features. The K-3 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 (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 and Sony A900 along with similar information for a selection of comparators.
|7.||Pentax K-3 II||optical||Y||3.2||1037||fixed||n||1/8000s||8.3||n||Y|
|10.||Pentax K-5 II||optical||Y||3.0||921||fixed||n||1/8000s||7.0||Y||Y|
|13.||Sony A99 II||2400||Y||3.0||1229||full-flex||n||1/8000s||12.0||n||Y|
|14.||Sony A7S II||2400||n||3.0||1229||tilting||n||1/8000s||5.0||n||Y|
One difference between the cameras concerns the presence of an on-board flash. The K-3 has one, while the A900 does not. While the built-in flash of the K-3 is not very powerful, it can at times be useful as a fill-in light.
The Pentax K-3 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 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 and Sony Alpha A900 and, in particular, the interfaces the cameras (and selected comparators) provide for accessory control and data transfer.
| WiFi |
| NFC |
|7.||Pentax K-3 II||Y||mono||mono||Y||Y||mini||3.0||-||-||-|
|10.||Pentax K-5 II||Y||stereo||mono||Y||-||mini||2.0||-||-||-|
|13.||Sony A99 II||Y||stereo||mono||Y||Y||micro||2.0||Y||Y||Y|
|14.||Sony A7S II||Y||stereo||mono||Y||Y||micro||2.0||Y||Y||-|
Both cameras feature a PC Sync terminal to control professional strobe lights, which will be appreciated by studio photographers.
Both the K-3 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 was followed by the Pentax K-3 II. 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 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:
- Maximized detail: Lacks an anti-alias filter to exploit the sensor's full resolution potential.
- More dynamic range: Captures a larger spectrum of light and dark details (1.1 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 fill-in: Is equipped with a small onboard flash to brighten deep shadow areas.
- Faster data transfer: Supports a more advanced USB protocol (3.0 vs 2.0).
- More affordable: Was introduced into a lower priced category (57 percent cheaper at launch).
- More modern: Reflects 5 years 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.
- Larger viewfinder image: Features a viewfinder with a higher magnification (0.74x vs 0.63x).
- Longer lasting: Gets more shots (880 versus 560) out of a single battery charge.
- More heavily discounted: Has been around for much longer (launched in September 2008).
If the count of relative strengths (bullet points above) is taken as a measure, the K-3 is the clear winner of the match-up (13 : 4 points). However, the relative importance of the various individual camera aspects will vary according to personal preferences and needs, so that you might like to apply corresponding weights to the particular features before making a decision on a new camera. A professional wildlife photographer will view the differences between cameras in a way that diverges from the perspective of a family photog, and a person interested in architecture has distinct needs from a sports 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 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 technical specifications can provide a useful overview of the capabilities of different cameras, it remains incomplete and does no justice, for example, to the way the K-3 or the A900 perform in practice. User reviews that are available, for instance, at amazon can sometimes shed light on these issues, but such feedback is all too often partial, inconsistent, and inaccurate.
This is where reviews by experts come in. The adjacent summary-table relays the overall verdicts of several of the most popular camera review sites (amateurphotographer [AP], cameralabs [CL], 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||4/5||..||83/100||5/5||5/5||Oct 2013||1,299|
|2.||Sony A900||..||+ +||+ +||4.5/5||5/5||Sep 2008||2,999|
|3.||Nikon D7100||5/5||+ +||85/100||4.5/5||4.5/5||Feb 2013||1,199|
|4.||Pentax KP||4/5||..||82/100||5/5||4.5/5||Jan 2017||1,099|
|5.||Pentax K-70||4.5/5||..||79/100||4.5/5||4.5/5||Jun 2016||649|
|6.||Pentax K-S2||4.5/5||..||..||5/5||4.5/5||Feb 2015||749|
|7.||Pentax K-3 II||4.5/5||..||..||5/5||5/5||Apr 2015||1,099|
|8.||Pentax K-S1||4/5||..||..||4.5/5||4/5||Aug 2014||749|
|9.||Pentax K-50||5/5||..||..||5/5||4.5/5||Jun 2013||599|
|10.||Pentax K-5 II||5/5||..||80/100||5/5||4.5/5||Sep 2012||1,099|
|11.||Pentax K-5||4/5||..||83/100||5/5||4.5/5||Sep 2010||1,099|
|12.||Sony A9||5/5||+ +||89/100||5/5||5/5||Apr 2017||4,499|
|13.||Sony A99 II||..||..||85/100||4.5/5||4.5/5||Sep 2016||3,199|
|14.||Sony A7S II||5/5||+||..||4.5/5||5/5||Sep 2015||2,999|
|15.||Sony A99||5/5||..||84/100||4.5/5||4.5/5||Sep 2012||2,799|
|16.||Sony A77||5/5||91/100||81/100||..||5/5||Aug 2011||1,399|
|17.||Sony A850||3/5||..||75/100||..||4.5/5||Aug 2009||1,999|
|Notes: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.|
The review scores listed above should be treated with care, though. The assessments were made in relation to similar cameras of the same technological generation. 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. Also, please note that some of the review sites have changed their methodology and reporting over time.
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. Alternatively, you can follow any of the listed hyperlinks for comparisons that others found interesting.
Specifications: Pentax K-3 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||Sony A900|
|Camera Type||Digital single lens reflex||Digital single lens reflex|
|Camera Lens||Pentax K mount lenses||Sony A mount lenses|
|Launch Date||October 2013||September 2008|
|Launch Price||USD 1,299||USD 2,999|
|Sensor Specs||Pentax K-3||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)||23.7||23.7|
|DXO Dynamic Range (EV)||13.4||12.3|
|DXO Low Light (ISO)||1216||1431|
|Screen Specs||Pentax K-3||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||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||Built-in 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||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|
|Body Specs||Pentax K-3||Sony A900|
|Environmental Sealing||Weathersealed body||Weathersealed body|
|Battery Life (CIPA)||560 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)|
Did you notice an error on this page? If so, please get in touch, so that we can correct the information.