Olympus E-M5 III vs Pentax K-S2
The Olympus OM-D E-M5 Mark III and the Pentax K-S2 are two digital cameras that were announced, respectively, in October 2019 and February 2015. The E-M5 III is a mirrorless interchangeable lens camera, while the K-S2 is a DSLR. The cameras are based on a Four Thirds (E-M5 III) and an APS-C (K-S2) sensor. The Olympus has a resolution of 20.2 megapixels, whereas the Pentax provides 20 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 Olympus OM-D E-M5 Mark III and the Pentax K-S2? 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 Olympus E-M5 III and the Pentax K-S2. The two cameras are presented according to their relative size. Three successive views from the front, the top, and the rear are shown. All width, height and depth dimensions are rounded to the nearest millimeter.
The E-M5 III can be obtained in two different colors (black, silver), while the K-S2 is available in six color-versions (black, grey, pink, orange, green, white).
If the front view area (width x height) of the cameras is taken as an aggregate measure of their size, the Pentax K-S2 is notably larger (5 percent) than the Olympus E-M5 III. Moreover, the K-S2 is substantially heavier (64 percent) than the E-M5 III. 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.
Concerning battery life, the E-M5 III gets 310 shots out of its BLS-50 battery, while the K-S2 can take 410 images on a single charge of its D-LI109 power pack. The power pack in the E-M5 III can be charged via the USB port, so that it is not always necessary to take the battery charger along when travelling.
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.||Olympus E-M5 III||125 mm||85 mm||50 mm||414 g||310||Y||Oct 2019||1,199|
|2.||Pentax K-S2||123 mm||91 mm||73 mm||678 g||410||Y||Feb 2015||749|
|3.||Olympus E-M1 III||134 mm||91 mm||69 mm||580 g||420||Y||Feb 2020||1,799|
|4.||Olympus E-M10 IV||122 mm||84 mm||49 mm||383 g||360||n||Aug 2020||699|
|5.||Olympus E-M1X||144 mm||147 mm||75 mm||997 g||870||Y||Jan 2019||2,999|
|6.||Olympus PEN-F||125 mm||72 mm||37 mm||427 g||330||n||Jan 2016||1,199|
|7.||Olympus E-M5 II||124 mm||85 mm||45 mm||469 g||310||Y||Feb 2015||1,099|
|8.||Olympus E-M1||130 mm||94 mm||63 mm||497 g||350||Y||Sep 2013||1,399|
|9.||Olympus E-M5||122 mm||89 mm||43 mm||425 g||360||Y||Feb 2012||1,299|
|10.||Panasonic G90||130 mm||94 mm||77 mm||536 g||290||Y||Apr 2019||999|
|11.||Panasonic GX8||133 mm||78 mm||63 mm||487 g||330||Y||Jul 2015||1,199|
|12.||Pentax KP||132 mm||101 mm||76 mm||703 g||390||Y||Jan 2017||1,099|
|13.||Pentax K-70||126 mm||93 mm||74 mm||688 g||410||Y||Jun 2016||649|
|14.||Pentax K-3 II||131 mm||100 mm||77 mm||800 g||720||Y||Apr 2015||1,099|
|15.||Pentax K-S1||121 mm||93 mm||70 mm||558 g||410||n||Aug 2014||749|
|16.||Pentax K-3||131 mm||100 mm||77 mm||800 g||560||Y||Oct 2013||1,299|
|17.||Sony A6600||120 mm||67 mm||69 mm||503 g||810||Y||Aug 2019||1,399|
|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-S2 was launched at a markedly lower price (by 38 percent) than the E-M5 III, 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.
The imaging sensor is at the core of digital cameras and its size is one of the main determining factors of image quality. All other things equal, a large sensor will have larger individual pixel-units that offer better low-light sensitivity, wider dynamic range, and richer color-depth than smaller pixels in a sensor of the same technological generation. Further, a large sensor camera will give the photographer additional creative options when using shallow depth-of-field to isolate a subject from its background. On the downside, larger sensors tend to be associated with larger, more expensive camera bodies and lenses.
Of the two cameras under consideration, the Olympus E-M5 III features a Four Thirds sensor and the Pentax K-S2 an APS-C sensor. The sensor area in the K-S2 is 63 percent bigger. As a result of these sensor size differences, the cameras have a format factor of, respectively, 2.0 and 1.5. The sensor in the E-M5 III has a native 4:3 aspect ratio, while the one in the K-S2 offers a 3:2 aspect.
Despite having a smaller sensor, the Olympus E-M5 III offers a higher resolution of 20.2 megapixels, compared with 20 MP of the Pentax K-S2. This megapixels advantage comes at the cost of a higher pixel density and a smaller size of the individual pixel (with a pixel pitch of 3.34μm versus 4.28μm for the K-S2). However, it should be noted that the E-M5 III is much more recent (by 4 years and 8 months) than the K-S2, and its sensor will have benefitted from technological advances during this time that make it possible to gather light more efficiently. Coming back to sensor resolution, it should be mentioned that neither of the two cameras has an anti-alias filter installed, so they are able to capture all the detail the sensor resolves.
The E-M5 III has on-sensor phase detect pixels, which results in fast and reliable autofocus acquisition even during live view operation.
Unlike the K-S2, the E-M5 III has the capacity to capture high quality composite images (80MP) 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 Olympus OM-D E-M5 Mark III has a native sensitivity range from ISO 200 to ISO 25600, which can be extended to ISO 64-25600. The corresponding ISO settings for the Pentax K-S2 are ISO 100 to ISO 51200 (no boost).
Since 2007, DXO Mark has published sensor performance measurements that have been derived using a consistent methodology. This service determines an overall sensor rating, as well as sub-scores for low-light sensitivity ("DXO Sports"), dynamic range ("DXO Landscape"), and color depth ("DXO Portrait"). The adjacent table reports on the physical sensor characteristics and the outcomes of the DXO sensor quality tests for a sample of comparator-cameras.
| DXO |
|1.||Olympus E-M5 III||Four Thirds||20.2||5184||3888||4K/30p||..||..||..||..|
|3.||Olympus E-M1 III||Four Thirds||20.2||5184||3888||4K/30p||..||..||..||..|
|4.||Olympus E-M10 IV||Four Thirds||20.2||5184||3888||4K/30p||..||..||..||..|
|5.||Olympus E-M1X||Four Thirds||20.2||5184||3888||4K/30p||..||..||..||..|
|6.||Olympus PEN-F||Four Thirds||20.2||5184||3888||1080/60p||23.1||12.4||894||74|
|7.||Olympus E-M5 II||Four Thirds||15.9||4608||3456||1080/60p||23.0||12.5||842||73|
|8.||Olympus E-M1||Four Thirds||15.9||4608||3456||1080/30p||23.0||12.7||757||73|
|9.||Olympus E-M5||Four Thirds||15.9||4608||3456||1080/60i||22.8||12.3||826||71|
|10.||Panasonic G90||Four Thirds||20.2||5184||3888||4K/30p||..||..||..||..|
|11.||Panasonic GX8||Four Thirds||20.2||5184||3888||4K/30p||23.5||12.6||806||75|
|14.||Pentax K-3 II||APS-C||24.1||6016||4000||1080/60i||23.6||13.6||1106||80|
Many modern cameras are not only capable of taking still images, but can also record movies. Both cameras under consideration have a sensor with sufficiently fast read-out times for moving pictures, but the E-M5 III provides a higher video resolution than the K-S2. It can shoot video footage at 4K/30p, while the Pentax is limited to 1080/30p.
Apart from body and sensor, cameras can and do differ across a range of features. For example, the E-M5 III has an electronic viewfinder (2360k dots), while the K-S2 has an optical one. Both systems have their advantages, with the electronic viewfinder making it possible to project supplementary shooting information into the framing view, whereas the optical viewfinder offers lag-free viewing and a very clear framing image. The viewfinders of both cameras offer the same field of view (100%), but the viewfinder of the E-M5 III has a higher magnification than the one of the K-S2 (0.68x vs 0.63x), so that the size of the image transmitted appears closer to the size seen with the naked human eye. The following table reports on some other key feature differences and similarities of the Olympus E-M5 III, the Pentax K-S2, and comparable cameras.
|1.||Olympus E-M5 III||2360||n||3.0||1040||swivel||Y||1/8000s||10.0||n||Y|
|3.||Olympus E-M1 III||2360||n||3.0||1037||swivel||Y||1/8000s||18.0||n||Y|
|4.||Olympus E-M10 IV||2360||n||3.0||1040||tilting||Y||1/4000s||15.0||Y||Y|
|7.||Olympus E-M5 II||2360||n||3.0||1037||swivel||Y||1/8000s||10.0||n||Y|
|14.||Pentax K-3 II||optical||Y||3.2||1037||fixed||n||1/8000s||8.3||n||Y|
One differentiating feature between the two cameras concerns the touch sensitivity of the rear screen. The E-M5 III has a touchscreen, while the K-S2 has a conventional panel. Touch control can be particularly helpful, for example, for setting the focus point.Both cameras have an articulated rear screen that can be turned to be front-facing. This feature will be particularly appreciated by vloggers and photographers who are interested in taking selfies.
The reported shutter speed information refers to the use of the mechanical shutter. Yet, some cameras only have an electronic shutter, while others have an electronic shutter in addition to a mechanical one. In fact, the E-M5 III is one of those camera that have an additional electronic shutter, which makes completely silent shooting possible. However, this mode is less suitable for photographing moving objects (risk of rolling shutter) or shooting under artificial light sources (risk of flickering).
The Olympus E-M5 III and the Pentax K-S2 both have 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.
Concerning the storage of imaging data, both the E-M5 III and the K-S2 write their files to SDXC cards. The E-M5 III supports UHS-II cards (Ultra High Speed data transfer of up to 312 MB/s), while the K-S2 can use UHS-I cards (up to 104 MB/s).
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 Olympus OM-D E-M5 Mark III and Pentax K-S2 and, in particular, the interfaces the cameras (and selected comparators) provide for accessory control and data transfer.
| WiFi |
| NFC |
|1.||Olympus E-M5 III||Y||stereo||mono||Y||-||micro||2.0||Y||-||Y|
|3.||Olympus E-M1 III||Y||stereo||mono||Y||Y||micro||3.1||Y||-||Y|
|4.||Olympus E-M10 IV||Y||stereo||mono||-||-||micro||2.0||Y||-||Y|
|7.||Olympus E-M5 II||Y||stereo||mono||Y||-||micro||2.0||Y||-||-|
|14.||Pentax K-3 II||Y||mono||mono||Y||Y||mini||3.0||-||-||-|
Both the E-M5 III and the K-S2 are recent models that are part of the current product line-up. The K-S2 replaced the earlier Pentax K-S1, while the E-M5 III followed on from the Olympus E-M5 II. Further information on the two cameras (e.g. user guides, manuals), as well as related accessories, can be found on the official Olympus and Pentax websites.
So how do things add up? Is the Olympus E-M5 III better than the Pentax K-S2 or vice versa? The listing below highlights the relative strengths of the two models.
Arguments in favor of the Olympus OM-D E-M5 Mark III:
- High quality composites: Can combine several shots after pixel-shifting its sensor.
- Better video: Provides higher definition movie capture (4K/30p vs 1080/30p).
- Better live-view autofocus: Features on-sensor phase-detection for more confident autofocus.
- More framing info: Has an electronic viewfinder that displays shooting data.
- Larger viewfinder image: Features a viewfinder with a higher magnification (0.68x vs 0.63x).
- More detailed LCD: Has a higher resolution rear screen (1040k vs 921k dots).
- Fewer buttons to press: Is equipped with a touch-sensitive rear screen to facilitate handling.
- Faster shutter: Has higher mechanical shutter speed (1/8000s vs 1/6000s) to freeze action.
- Faster burst: Shoots at higher frequency (10 vs 5.4 flaps/sec) to capture the decisive moment.
- Less disturbing: Has an electronic shutter option for completely silent shooting.
- Less heavy: Is lighter (by 264g or 39 percent) and hence easier to carry around.
- Easier travel charging: Can be conveniently charged via its USB port.
- More legacy lens friendly: Can take a broad range of non-native lenses via adapters.
- Easier wireless transfer: Supports Bluetooth for image sharing without cables.
- Faster buffer clearing: Supports a more advanced SD data transfer standard (UHS-II vs UHS-I).
- More modern: Reflects 4 years and 8 months of technical progress since the K-S2 launch.
Reasons to prefer the Pentax K-S2:
- Brighter framing: Features an optical viewfinder for clear, lag-free composition.
- Longer lasting: Gets more shots (410 versus 310) out of a single battery charge.
- Easier fill-in: Has a small integrated flash to brighten shadows of backlit subjects.
- Easier device pairing: Supports NFC for fast wireless image transfer over short distances.
- More affordable: Was introduced into a lower priced category (38 percent cheaper at launch).
- More heavily discounted: Has been around for much longer (launched in February 2015).
If the count of individual advantages (bullet points above) is taken as a guide, the E-M5 III is the clear winner of the match-up (16 : 6 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 Olympus E-M5 III and the Pentax K-S2 place the cameras among the top in their class? Find out in the latest Best Mirrorless Interchangeable Lens Camera and Best DSLR Camera listings 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 E-M5 III and the K-S2 in practical situations. 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 why expert reviews are important. The following table reports the overall ratings of the cameras as published by some of the major 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.||Olympus E-M5 III||5/5||+||82/100||4.5/5||4.5/5||Oct 2019||1,199|
|2.||Pentax K-S2||4.5/5||..||..||5/5||4.5/5||Feb 2015||749|
|3.||Olympus E-M1 III||5/5||..||83/100||4.5/5||4/5||Feb 2020||1,799|
|4.||Olympus E-M10 IV||4.5/5||..||..||4.5/5||4.5/5||Aug 2020||699|
|5.||Olympus E-M1X||4.5/5||o||..||4.5/5||..||Jan 2019||2,999|
|6.||Olympus PEN-F||..||..||82/100||4.5/5||5/5||Jan 2016||1,199|
|7.||Olympus E-M5 II||5/5||+ +||81/100||5/5||5/5||Feb 2015||1,099|
|8.||Olympus E-M1||5/5||+ +||84/100||4.5/5||4.5/5||Sep 2013||1,399|
|9.||Olympus E-M5||4/5||+ +||80/100||4.5/5||5/5||Feb 2012||1,299|
|10.||Panasonic G90||4.5/5||+||83/100||4.5/5||4.5/5||Apr 2019||999|
|11.||Panasonic GX8||5/5||+||82/100||4.5/5||4.5/5||Jul 2015||1,199|
|12.||Pentax KP||4/5||..||82/100||5/5||4.5/5||Jan 2017||1,099|
|13.||Pentax K-70||4.5/5||..||79/100||4.5/5||4.5/5||Jun 2016||649|
|14.||Pentax K-3 II||4.5/5||..||..||5/5||5/5||Apr 2015||1,099|
|15.||Pentax K-S1||4/5||..||..||4.5/5||4/5||Aug 2014||749|
|16.||Pentax K-3||4/5||..||83/100||5/5||5/5||Oct 2013||1,299|
|17.||Sony A6600||4/5||+||83/100||4.5/5||4/5||Aug 2019||1,399|
|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 rating-comparisons among cameras that span long time periods or concern very differently equipped models make little sense. 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. As an alternative, you can also directly jump to any one of the listed comparisons that were previously generated by the CAM-parator tool.
Specifications: Olympus E-M5 III vs Pentax K-S2
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||Olympus E-M5 III||Pentax K-S2|
|Camera Type||Mirrorless system camera||Digital single lens reflex|
|Camera Lens||Micro Four Thirds lenses||Pentax K mount lenses|
|Launch Date||October 2019||February 2015|
|Launch Price||USD 1,199||USD 749|
|Sensor Specs||Olympus E-M5 III||Pentax K-S2|
|Sensor Format||Four Thirds Sensor||APS-C Sensor|
|Sensor Size||17.3 x 13.0 mm||23.5 x 15.6 mm|
|Sensor Area||224.9 mm2||366.6 mm2|
|Sensor Diagonal||21.6 mm||28.2 mm|
|Sensor Resolution||20.2 Megapixels||20 Megapixels|
|Image Resolution||5184 x 3888 pixels||5472 x 3648 pixels|
|Pixel Pitch||3.34 μm||4.28 μm|
|Pixel Density||8.96 MP/cm2||5.45 MP/cm2|
|Moiré control||no AA filter||no AA filter|
|Movie Capability||4K/30p Video||1080/30p Video|
|ISO Setting||200 - 25,600 ISO||100 - 51,200 ISO|
|ISO Boost||64 - 25,600 ISO||no Enhancement|
|Image Processor||TruePic VIII||PRIME MII|
|Screen Specs||Olympus E-M5 III||Pentax K-S2|
|Viewfinder Type||Electronic viewfinder||Optical viewfinder|
|Viewfinder Field of View||100%||100%|
|Viewfinder Resolution||2360k dots|
|LCD Framing||Live View||Live View|
|Rear LCD Size||3.0inch||3.0inch|
|LCD Resolution||1040k dots||921k dots|
|LCD Attachment||Swivel screen||Swivel screen|
|Touch Input||Touchscreen||no Touchscreen|
|Shooting Specs||Olympus E-M5 III||Pentax K-S2|
|Focus System||On-Sensor Phase-detect||Phase-detect AF|
|Manual Focusing Aid||Focus Peaking||Focus Peaking|
|Max Shutter Speed (mechanical)||1/8000s||1/6000s|
|Continuous Shooting||10 shutter flaps/s||5.4 shutter flaps/s|
|Electronic Shutter||up to 1/32000s||no E-Shutter|
|Time-Lapse Photography||Intervalometer built-in||Intervalometer built-in|
|Image Stabilization||In-body stabilization||In-body stabilization|
|Fill Flash||no On-Board Flash||Build-in Flash|
|Storage Medium||SDXC cards||SDXC cards|
|Second Storage Option||Single card slot||Single card slot|
|UHS card support||UHS-II||UHS-I|
|Connectivity Specs||Olympus E-M5 III||Pentax K-S2|
|USB Connector||USB 2.0||USB 2.0|
|HDMI Port||micro HDMI||micro HDMI|
|Microphone Port||External MIC port||External MIC port|
|Wifi Support||Wifi built-in||Wifi built-in|
|Near-Field Communication||no NFC||NFC built-in|
|Bluetooth Support||Bluetooth built-in||no Bluetooth|
|Body Specs||Olympus E-M5 III||Pentax K-S2|
|Environmental Sealing||Weathersealed body||Weathersealed body|
|Battery Life (CIPA)||310 shots per charge||410 shots per charge|
|In-Camera Charging||USB charging||no USB charging|
125 x 85 x 50 mm
(4.9 x 3.3 x 2.0 in)
123 x 91 x 73 mm
(4.8 x 3.6 x 2.9 in)
|Camera Weight||414 g (14.6 oz)||678 g (23.9 oz)|
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