Olympus E-M10 III vs Pentax 645D
The Olympus OM-D E-M10 Mark III and the Pentax 645D are two digital cameras that were announced, respectively, in August 2017 and March 2010. The E-M10 III is a mirrorless interchangeable lens camera, while the 645D is a DSLR. The cameras are based on a Four Thirds (E-M10 III) and a medium format (645D) sensor. The Olympus has a resolution of 15.9 megapixels, whereas the Pentax provides 39.5 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-M10 Mark III and the Pentax 645D? 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-M10 III and the Pentax 645D. 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 measures are rounded to the nearest millimeter.
The E-M10 III can be obtained in two different colors (black, silver), while the 645D 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 Pentax 645D is considerably larger (78 percent) than the Olympus E-M10 III. Moreover, the 645D is substantially heavier (261 percent) than the E-M10 III. It is noteworthy in this context that the 645D is splash and dust-proof, while the E-M10 III does not feature any corresponding weather-sealing.
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 want to switch the focus of the display and review another camera pair, you can move across to the CAM-parator tool and choose from the broad selection of possible camera comparisons there.
|1.||Olympus E-M10 III||122 mm||84 mm||50 mm||410 g||330||n||Aug 2017||649|
|2.||Pentax 645D||156 mm||117 mm||119 mm||1480 g||800||Y||Mar 2010||9,995|
|3.||Canon 1D X||158 mm||168 mm||83 mm||1551 g||1120||Y||Oct 2011||6,799|
|4.||Canon 1D Mark IV||156 mm||157 mm||80 mm||1230 g||1500||Y||Oct 2009||4,999|
|5.||Leica S Typ 006||160 mm||120 mm||80 mm||1260 g||..||Y||Sep 2012||21,950|
|6.||Nikon D3S||160 mm||157 mm||88 mm||1240 g||4200||Y||Oct 2009||5,199|
|7.||Olympus E-M10 IV||122 mm||84 mm||49 mm||383 g||360||n||Aug 2020||699|
|8.||Olympus E-PL10||117 mm||68 mm||39 mm||380 g||350||n||Oct 2019||599|
|9.||Olympus E-PL9||117 mm||68 mm||39 mm||380 g||350||n||Feb 2018||599|
|10.||Olympus E-PL8||115 mm||67 mm||38 mm||357 g||350||n||Sep 2016||549|
|11.||Olympus PEN-F||125 mm||72 mm||37 mm||427 g||330||n||Jan 2016||1,199|
|12.||Olympus E-M10 II||120 mm||83 mm||47 mm||390 g||320||n||Aug 2015||649|
|13.||Olympus E-M10||119 mm||82 mm||46 mm||396 g||320||n||Jan 2014||699|
|14.||Olympus E-PL7||115 mm||67 mm||38 mm||357 g||350||n||Aug 2014||599|
|15.||Olympus E-PL6||111 mm||64 mm||38 mm||325 g||360||n||May 2013||599|
|16.||Panasonic GX85||122 mm||71 mm||44 mm||426 g||290||n||Apr 2016||799|
|17.||Pentax 645Z||156 mm||117 mm||123 mm||1550 g||650||Y||Apr 2014||8,499|
|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 listed launch prices provide an indication of the market segment that the manufacturer of the cameras have been targeting. The E-M10 III was launched at a markedly lower price (by 94 percent) than the 645D, 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. 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. Furthermore, a large sensor camera will give the photographer more possibilities to use shallow depth-of-field in order to 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 Olympus E-M10 III features a Four Thirds sensor and the Pentax 645D a medium format sensor. The sensor area in the 645D is 545 percent bigger. As a result of these sensor size differences, the cameras have a format factor of, respectively, 2.0 and 0.79. Both cameras feature a native aspect ratio (sensor width to sensor height) of 4:3.
With 39.5MP, the 645D offers a higher resolution than the E-M10 III (15.9MP), but the 645D nevertheless has larger individual pixels (pixel pitch of 6.06μm versus 3.76μm for the E-M10 III) due to its larger sensor. However, the E-M10 III is a much more recent model (by 7 years and 5 months) than the 645D, 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 neither of the two cameras has an anti-alias filter installed, so they are able to capture all the detail the sensor resolves.
The resolution advantage of the Pentax 645D implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the 645D for good quality output (200 dots per inch) amounts to 36.3 x 27.2 inches or 92.3 x 69.1 cm, for very good quality (250 dpi) 29.1 x 21.8 inches or 73.8 x 55.3 cm, and for excellent quality (300 dpi) 24.2 x 18.1 inches or 61.5 x 46.1 cm. The corresponding values for the Olympus E-M10 III are 23 x 17.3 inches or 58.5 x 43.9 cm for good quality, 18.4 x 13.8 inches or 46.8 x 35.1 cm for very good quality, and 15.4 x 11.5 inches or 39 x 29.3 cm for excellent quality prints.
The Olympus OM-D E-M10 Mark III has a native sensitivity range from ISO 200 to ISO 25600, which can be extended to ISO 100-25600. The corresponding ISO settings for the Pentax 645D are ISO 100 to ISO 1600 (no boost).
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 table below summarizes the physical sensor characteristics and sensor quality findings and compares them across a set of similar cameras.
| DXO |
|1.||Olympus E-M10 III||Four Thirds||15.9||4608||3456||4K/30p||..||..||..||..|
|2.||Pentax 645D||Medium Format||39.5||7264||5440||none||24.6||12.6||1262||82|
|3.||Canon 1D X||Full Frame||17.9||5184||3456||1080/30p||23.8||11.8||2786||82|
|4.||Canon 1D Mark IV||APS-H||16.0||4896||3264||1080/30p||22.8||12.0||1320||74|
|5.||Leica S Typ 006||Medium Format||37.5||7500||5000||none||23.9||12.2||824||76|
|6.||Nikon D3S||Full Frame||12.1||4256||2832||720/24p||23.5||12.0||3253||82|
|7.||Olympus E-M10 IV||Four Thirds||20.2||5184||3888||4K/30p||..||..||..||..|
|8.||Olympus E-PL10||Four Thirds||15.9||4608||3456||4K/30p||..||..||..||..|
|9.||Olympus E-PL9||Four Thirds||15.9||4608||3456||4K/30p||..||..||..||..|
|10.||Olympus E-PL8||Four Thirds||15.9||4608||3456||1080/30p||..||..||..||..|
|11.||Olympus PEN-F||Four Thirds||20.2||5184||3888||1080/60p||23.1||12.4||894||74|
|12.||Olympus E-M10 II||Four Thirds||15.9||4608||3456||1080/60p||23.1||12.5||842||73|
|13.||Olympus E-M10||Four Thirds||15.9||4608||3456||1080/30p||22.8||12.3||884||72|
|14.||Olympus E-PL7||Four Thirds||15.9||4608||3456||1080/30p||22.7||12.4||873||72|
|15.||Olympus E-PL6||Four Thirds||15.9||4608||3456||1080/30p||..||..||..||..|
|16.||Panasonic GX85||Four Thirds||15.8||4592||3448||4K/30p||22.9||12.6||662||71|
|17.||Pentax 645Z||Medium Format||51.1||8256||6192||1080/60i||26.0||14.7||4505||101|
Many modern cameras are not only capable of taking still images, but also of capturing video footage. The E-M10 III indeed provides movie recording capabilities, while the 645D does not. The highest resolution format that the E-M10 III can use is 4K/30p.
Apart from body and sensor, cameras can and do differ across a variety of features. For example, the E-M10 III has an electronic viewfinder (2360k dots), while the 645D 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 viewfinder in the E-M10 III offers a wider field of view (100%) than the one in the 645D (98%), so that a larger proportion of the captured image is visible in the finder. On the other hand, the viewfinder of the 645D has a higher magnification (0.78x vs 0.62x), so that the size of the image transmitted appears closer to the size seen with the naked human eye. The table below summarizes some of the other core capabilities of the Olympus E-M10 III and Pentax 645D in connection with corresponding information for a sample of similar cameras.
|1.||Olympus E-M10 III||2360||n||3.0||1040||tilting||Y||1/4000s||8.6||Y||Y|
|3.||Canon 1D X||optical||Y||3.2||1040||fixed||n||1/8000s||14.0||n||n|
|4.||Canon 1D Mark IV||optical||Y||3.0||920||fixed||n||1/8000s||10.0||n||n|
|5.||Leica S Typ 006||optical||Y||3.0||922||fixed||n||1/4000s||1.5||n||n|
|7.||Olympus E-M10 IV||2360||n||3.0||1040||tilting||Y||1/4000s||15.0||Y||Y|
|12.||Olympus E-M10 II||2360||n||3.0||1040||tilting||Y||1/4000s||8.0||Y||Y|
One difference between the cameras concerns the presence of an on-board flash. The E-M10 III has one, while the 645D does not. While the built-in flash of the E-M10 III is not very powerful, it can at times be useful as a fill-in light.
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-M10 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-M10 III and the Pentax 645D 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-M10 III and the 645D write their files to SDXC cards. The 645D features dual card slots, which can be very useful in case a memory card fails. In contrast, the E-M10 III only has one slot. The E-M10 III supports UHS-II cards (Ultra High Speed data transfer of up to 312 MB/s), while the 645D cannot take advantage of Ultra High Speed SD cards.
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-M10 Mark III and Pentax 645D and, in particular, the interfaces the cameras (and selected comparators) provide for accessory control and data transfer.
| WiFi |
| NFC |
|1.||Olympus E-M10 III||Y||stereo||mono||-||-||micro||2.0||Y||-||-|
|3.||Canon 1D X||Y||mono||-||Y||-||mini||2.0||-||-||-|
|4.||Canon 1D Mark IV||Y||stereo||-||Y||-||mini||2.0||-||-||-|
|5.||Leica S Typ 006||Y||-||-||-||-||mini||2.0||-||-||-|
|7.||Olympus E-M10 IV||Y||stereo||mono||-||-||micro||2.0||Y||-||Y|
|12.||Olympus E-M10 II||Y||stereo||mono||-||-||micro||2.0||Y||-||-|
It is notable that the E-M10 III offers wifi support, while the 645D does not. Wifi can be a very convenient means to transfer image data to an off-camera location.
Studio photographers will appreciate that the Pentax 645D (unlike the E-M10 III) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.
Both the E-M10 III and the 645D have been discontinued, but can regularly be found used on eBay. The 645D was replaced by the Pentax 645Z, while the E-M10 III was followed by the Olympus E-M10 IV. 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 what is the bottom line? Which of the two cameras – the Olympus E-M10 III or the Pentax 645D – has the upper hand? Is one clearly better than the other? Below is a summary of the relative strengths of each of the two contestants.
Advantages of the Olympus OM-D E-M10 Mark III:
- Broader imaging potential: Can record not only still images but also 4K/30p movies.
- More framing info: Has an electronic viewfinder that displays shooting data.
- More complete view: Has a viewfinder with a larger field of view (100% vs 98%).
- More detailed LCD: Has a higher resolution rear screen (1040k vs 921k dots).
- More flexible LCD: Has a tilting screen for odd-angle shots in landscape orientation.
- Fewer buttons to press: Is equipped with a touch-sensitive rear screen to facilitate handling.
- Faster burst: Shoots at higher frequency (8.6 vs 1.1 flaps/sec) to capture the decisive moment.
- Less disturbing: Has an electronic shutter option for completely silent shooting.
- More compact: Is smaller (122x84mm vs 156x117mm) and thus needs less room in the bag.
- Less heavy: Is lighter (by 1070g or 72 percent) and hence easier to carry around.
- Sharper images: Has hand-shake reducing image stabilization built-in.
- More legacy lens friendly: Can take a broad range of non-native lenses via adapters.
- Easier fill-in: Is equipped with a small onboard flash to brighten deep shadow areas.
- Easier file upload: Has wifi built in for automatic backup or image transfer to the web.
- Faster buffer clearing: Supports Ultra High Speed (UHS-II) SDXC cards.
- More affordable: Was introduced into a lower priced category (94 percent cheaper at launch).
- More modern: Reflects 7 years and 5 months of technical progress since the 645D launch.
Reasons to prefer the Pentax 645D:
- More detail: Has more megapixels (39.5 vs 15.9MP), which boosts linear resolution by 58%.
- Brighter framing: Features an optical viewfinder for clear, lag-free composition.
- Larger viewfinder image: Features a viewfinder with a higher magnification (0.78x vs 0.62x).
- Easier setting verification: Features a control panel on top to check shooting parameters.
- Longer lasting: Gets more shots (800 versus 330) out of a single battery charge.
- Better sealing: Is splash and dust sealed for shooting in inclement weather conditions.
- Better studio light control: Has a PC Sync socket to connect to professional strobe lights.
- Greater peace of mind: Features a second card slot as a backup in case of memory card failure.
- More heavily discounted: Has been around for much longer (launched in March 2010).
If the count of individual advantages (bullet points above) is taken as a guide, the E-M10 III is the clear winner of the match-up (17 : 9 points). However, the relevance of individual strengths will vary across photographers, so that you might want to apply your own weighing scheme to the summary points when reflecting and deciding on a new camera. A professional sports photographer will view the differences between cameras in a way that diverges from the perspective of a street photog, and a person interested in family portraits has distinct needs from a landscape 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-M10 III and the Pentax 645D 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 technical specifications can provide a useful overview of the capabilities of different cameras, it remains partial and cannot reveal, for example, the shooting experience and imaging performance when actually working with the E-M10 III or the 645D. 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 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-M10 III||..||+||80/100||4.5/5||4.5/5||Aug 2017||649|
|2.||Pentax 645D||5/5||..||..||..||..||Mar 2010||9,995|
|3.||Canon 1D X||5/5||..||..||4.5/5||4.5/5||Oct 2011||6,799|
|4.||Canon 1D Mark IV||5/5||..||89/100||..||..||Oct 2009||4,999|
|5.||Leica S Typ 006||..||..||..||..||..||Sep 2012||21,950|
|6.||Nikon D3S||5/5||..||89/100||4.5/5||5/5||Oct 2009||5,199|
|7.||Olympus E-M10 IV||4.5/5||..||..||4.5/5||4.5/5||Aug 2020||699|
|8.||Olympus E-PL10||..||..||77/100||..||4/5||Oct 2019||599|
|9.||Olympus E-PL9||..||+||..||4.5/5||4/5||Feb 2018||599|
|10.||Olympus E-PL8||..||..||..||4.5/5||4/5||Sep 2016||549|
|11.||Olympus PEN-F||..||..||82/100||4.5/5||5/5||Jan 2016||1,199|
|12.||Olympus E-M10 II||4.5/5||+ +||80/100||5/5||5/5||Aug 2015||649|
|13.||Olympus E-M10||4/5||..||80/100||5/5||5/5||Jan 2014||699|
|14.||Olympus E-PL7||4/5||+||..||5/5||4/5||Aug 2014||599|
|15.||Olympus E-PL6||..||..||..||..||..||May 2013||599|
|16.||Panasonic GX85||4.5/5||+ +||82/100||5/5||5/5||Apr 2016||799|
|17.||Pentax 645Z||5/5||..||..||4.5/5||5/5||Apr 2014||8,499|
|Notes: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.|
The above review scores should be interpreted with care, though. The ratings were established in reference to similarly priced cameras that were available in the market at the time of the review. Hence, a score should always be seen in the context of the camera's market launch date and its price, 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 a corresponding selection in the search boxes below. There is also a set of direct links to comparison reviews that other users of the CAM-parator app explored.
Specifications: Olympus E-M10 III vs Pentax 645D
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-M10 III||Pentax 645D|
|Camera Type||Mirrorless system camera||Digital single lens reflex|
|Camera Lens||Micro Four Thirds lenses||Pentax 645 mount lenses|
|Launch Date||August 2017||March 2010|
|Launch Price||USD 649||USD 9,995|
|Sensor Specs||Olympus E-M10 III||Pentax 645D|
|Sensor Format||Four Thirds Sensor||Medium Format Sensor|
|Sensor Size||17.3 x 13.0 mm||44.0 x 33.0 mm|
|Sensor Area||224.9 mm2||1452 mm2|
|Sensor Diagonal||21.6 mm||55 mm|
|Sensor Resolution||15.9 Megapixels||39.5 Megapixels|
|Image Resolution||4608 x 3456 pixels||7264 x 5440 pixels|
|Pixel Pitch||3.76 μm||6.06 μm|
|Pixel Density||7.08 MP/cm2||2.72 MP/cm2|
|Moiré control||no AA filter||no AA filter|
|Movie Capability||4K/30p Video||no Video|
|ISO Setting||200 - 25,600 ISO||100 - 1,600 ISO|
|ISO Boost||100 - 25,600 ISO||no Enhancement|
|Image Processor||TruePic VIII||PRIME II|
|DXO Sensor Quality (score)||..||82|
|DXO Color Depth (bits)||..||24.6|
|DXO Dynamic Range (EV)||..||12.6|
|DXO Low Light (ISO)||..||1262|
|Screen Specs||Olympus E-M10 III||Pentax 645D|
|Viewfinder Type||Electronic viewfinder||Optical viewfinder|
|Viewfinder Field of View||100%||98%|
|Viewfinder Resolution||2360k dots|
|Top-Level Screen||no Top Display||Control Panel|
|LCD Framing||Live View|
|Rear LCD Size||3.0inch||3.0inch|
|LCD Resolution||1040k dots||921k dots|
|LCD Attachment||Tilting screen||Fixed screen|
|Touch Input||Touchscreen||no Touchscreen|
|Shooting Specs||Olympus E-M10 III||Pentax 645D|
|Focus System||Contrast-detect AF||Phase-detect AF|
|Manual Focusing Aid||Focus Peaking||no Peaking Feature|
|Continuous Shooting||8.6 shutter flaps/s||1.1 shutter flaps/s|
|Electronic Shutter||up to 1/16000s||no E-Shutter|
|Time-Lapse Photography||Intervalometer built-in||Intervalometer built-in|
|Image Stabilization||In-body stabilization||Lens stabilization only|
|Fill Flash||Build-in Flash||no On-Board Flash|
|Storage Medium||SDXC cards||SDXC cards|
|Second Storage Option||Single card slot||Dual card slots|
|UHS card support||UHS-II||no|
|Connectivity Specs||Olympus E-M10 III||Pentax 645D|
|Studio Flash||no PC Sync||PC Sync socket|
|USB Connector||USB 2.0||USB 2.0|
|HDMI Port||micro HDMI||no HDMI|
|Wifi Support||Wifi built-in||no Wifi|
|Body Specs||Olympus E-M10 III||Pentax 645D|
|Environmental Sealing||not weather sealed||Weathersealed body|
|Battery Life (CIPA)||330 shots per charge||800 shots per charge|
122 x 84 x 50 mm
(4.8 x 3.3 x 2.0 in)
156 x 117 x 119 mm
(6.1 x 4.6 x 4.7 in)
|Camera Weight||410 g (14.5 oz)||1480 g (52.2 oz)|
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