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Pentax 645Z versus Olympus E-M10

The Pentax 645Z and the Olympus OM-D E-M10 are two digital cameras that were officially introduced, respectively, in April 2014 and January 2014. The 645Z is a DSLR, while the E-M10 is a mirrorless interchangeable lens camera. The cameras are based on a medium format (645Z) and a Four Thirds sensor. The Pentax has a resolution of 51.1 megapixel, whereas the Olympus provides 15.9 MP.

Body comparison

An illustration of the physical size and weight of the Pentax 645Z and the Olympus E-M10 is provided in the side-by-side display below. 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. You can also toggle the display to switch to a percentage comparison if you prefer that the measures are being expressed in relative terms (in this case, the camera on the left side – the 645Z – represents the basis for the calculations across all the size and weight measures).

Pentax 645Z vs Olympus E-M10 front
645Z versus E-M10 top view
645Z and E-M10 rear side
Body view (645Z on the left)

If the front view area (width x height) of the cameras is taken as an aggregate measure of their size, the Olympus E-M10 is considerably smaller (47 percent) than the Pentax 645Z. Moreover, the E-M10 is substantially lighter (74 percent) than the 645Z. It is worth mentioning in this context that the 645Z is splash and dust resistant, while the E-M10 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 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, just select a new right or left comparator from among the camera models in the table. Alternatively, you can also move across to the CAM-parator tool and choose from the broad selection of possible comparisons there.

Camera Body Specifications
Camera Camera
Width
Camera
Height
Camera
Depth
Camera
Weight
Battery
Life
(CIPA)
Weather
Sealing
(y/n)
Camera
Launch
(year)
Launch
Price
(USD)
Street
Price
(amazon)
Used
Price
(ebay)
Pentax 645Z (⇒ rgt) 156 mm 117 mm 123 mm 1550 g 650 YES 2014 8,499 latest check
Olympus E-M10 (⇒ lft) 119 mm 82 mm 46 mm 396 g 320 no 2014 699discont. check
Canon 5DS R (⇒ lft | rgt) 152 mm 116 mm 76 mm 930 g 700 YES 2015 3,699 latest check
Canon 5DS (⇒ lft | rgt) 152 mm 116 mm 76 mm 930 g 700 YES 2015 3,699 latest check
Hasselblad X1D (⇒ lft | rgt) 150 mm 98 mm 71 mm 725 g .. YES 2016 8,995 latest check
Leica SL (⇒ lft | rgt) 147 mm 104 mm 39 mm 847 g 400 YES 2015 7,450 latest check
Nikon D750 (⇒ lft | rgt) 141 mm 113 mm 78 mm 750 g 1230 YES 2014 2,299 latest check
Nikon D810 (⇒ lft | rgt) 146 mm 123 mm 82 mm 980 g 1200 YES 2014 3,299discont. check
Nikon D4S (⇒ lft | rgt) 160 mm 157 mm 91 mm 1350 g 3020 YES 2014 6,499discont. check
Olympus E-M10 III (⇒ lft | rgt) 122 mm 84 mm 50 mm 410 g 330 no 2017 649 latest check
Olympus E-M10 II (⇒ lft | rgt) 120 mm 83 mm 47 mm 390 g 320 no 2015 799discont. check
Olympus E-M5 II (⇒ lft | rgt) 124 mm 85 mm 45 mm 469 g 310 YES 2015 1,099 latest check
Olympus E-M1 (⇒ lft | rgt) 130 mm 94 mm 63 mm 497 g 350 YES 2013 1,399discont. check
Olympus E-P5 (⇒ lft | rgt) 122 mm 69 mm 37 mm 420 g 330 no 2013 999discont. check
Pentax 645D (⇒ lft | rgt) 156 mm 117 mm 119 mm 1480 g .. YES 2010 9,995discont. check
Sony RX1R II (⇒ lft | rgt) 113 mm 65 mm 72 mm 507 g 220 no 2015 3,299 latest check
Sony A7S (⇒ lft | rgt) 127 mm 94 mm 48 mm 489 g 380 YES 2014 2,499discont. check

The listed prices provide an indication of the market segment that the manufacturer of the cameras have been targeting. The E-M10 was launched at a markedly lower price (by 92 percent) than the 645Z, 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.

Sensor comparison

The imaging sensor is at the core of digital cameras and its size is one of the main determining factors 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. 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 Pentax 645Z features a medium format sensor and the Olympus E-M10 a Four Thirds sensor. The sensor area in the E-M10 is 84 percent smaller. As a result of these sensor size differences, the cameras have a format factor of, respectively, 0.79 and 2.0. Both cameras feature a native aspect ratio (sensor width to sensor height) of 4:3.

Pentax 645Z and Olympus E-M10 sensor measures
Sensor size

With 51.1MP, the 645Z offers a higher resolution than the E-M10 (15.9MP), but the 645Z nevertheless has larger individual pixels (pixel pitch of 5.30μm versus 3.76μm for the E-M10) due to its larger sensor. It is noteworthy in this context that the two cameras were released in close succession, so that their sensors are from the same technological generation. 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.

645Z versus E-M10 MP
Sensor resolution

Consistent information on actual sensor performance is available from DXO Mark for most 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. Of the two cameras under review, the 645Z provides substantially higher image quality than the E-M10, with an overall score that is 29 points higher. This advantage is based on 3.2 bits higher color depth, 2.4 EV in additional dynamic range, and 2.3 stops in additional low light sensitivity. The adjacent table reports on the physical sensor characteristics and the outcomes of the DXO sensor quality tests for a sample of comparator-cameras.

Sensor Characteristics
Camera Sensor
Class
Resolution
(Megapixel)
Horiz.
Pixels
Vert.
Pixels
Video
Format
DXO
Portrait
DXO
Landscape
DXO
Sports
DXO
Overall
Pentax 645Z (⇒ rgt) Medium Format 51.1 8256 6192 1080/60i 26.0 14.7 4505 101
Olympus E-M10 (⇒ lft) Four Thirds 15.9 4608 3456 1080/30p 22.8 12.3 884 72
Canon 5DS R (⇒ lft | rgt) Full Frame 50.3 8688 5792 1080/60p 24.6 12.4 2308 86
Canon 5DS (⇒ lft | rgt) Full Frame 50.3 8688 5792 1080/60p 24.7 12.4 2381 87
Hasselblad X1D (⇒ lft | rgt) Medium Format 51.3 8272 6200 1080/25p 26.2 14.8 4489 102
Leica SL (⇒ lft | rgt) Full Frame 24.0 6000 4000 4K/30p 25.0 13.4 1821 88
Nikon D750 (⇒ lft | rgt) Full Frame 24.2 6016 4016 1080/60p 24.8 14.5 2956 93
Nikon D810 (⇒ lft | rgt) Full Frame 36.2 7360 4912 1080/60p 25.7 14.8 2853 97
Nikon D4S (⇒ lft | rgt) Full Frame 16.2 4928 3280 1080/60p 24.4 13.3 3074 89
Olympus E-M10 III (⇒ lft | rgt) Four Thirds 15.9 4608 3456 4K/30p .. .. .. ..
Olympus E-M10 II (⇒ lft | rgt) Four Thirds 15.9 4608 3456 1080/60p 23.1 12.5 842 73
Olympus E-M5 II (⇒ lft | rgt) Four Thirds 15.9 4608 3456 1080/60p 23.0 12.5 842 73
Olympus E-M1 (⇒ lft | rgt) Four Thirds 15.9 4608 3456 1080/30p 23.0 12.7 757 73
Olympus E-P5 (⇒ lft | rgt) Four Thirds 15.9 4608 3456 1080/30p 22.8 12.4 895 72
Pentax 645D (⇒ lft | rgt) Medium Format 39.5 7264 5440 no 24.6 12.6 1262 82
Sony RX1R II (⇒ lft | rgt) Full Frame 42.2 7952 5304 1080/60p 25.8 13.9 3204 97
Sony A7S (⇒ lft | rgt) Full Frame 12.0 4240 2832 1080/60p 23.9 13.2 3702 87

Many modern cameras are not only capable of taking still images, but also of capturing video footage. Both cameras under consideration have a sensor with sufficiently fast read-out times for moving pictures, but the 645Z provides a higher frame rate than the E-M10. It can shoot video footage at 1080/60i, while the Olympus is limited to 1080/30p.

Feature comparison

Beyond body and sensor, cameras can and do differ across a range of features. For example, the E-M10 has an electronic viewfinder (1440k dots), while the 645Z 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 adjacent table lists some of the other core features of the Pentax 645Z and Olympus E-M10 along with similar information for a selection of comparators. The full specs-sheets can be found in the camera manual or, for example, in the dpreview camera hub.

Core Features
Camera Viewfinder
(Type or
'000 dots)
Control
Panel
(Y/n)
LCD
Size
(inch)
LCD
Resolution
('000 dots)
LCD
Attach-
ment
Touch
Screen
(Y/n)
Shutter
speed
(1/sec)
Shutter
flaps
(1/sec))
Build-in
Flash
(GN)
Build-in
Image
Stab
Pentax 645Z (⇒ rgt) optical YES 3.2 1037 tilting no 4000 3.0 no no
Olympus E-M10 (⇒ lft) 1440 no 3.0 1037 tilting YES 4000 8.0 5.8 YES
Canon 5DS R (⇒ lft | rgt) optical YES 3.2 1040 fixed no 8000 5.0 no no
Canon 5DS (⇒ lft | rgt) optical YES 3.2 1040 fixed no 8000 5.0 no no
Hasselblad X1D (⇒ lft | rgt) 2360 no 3.0 920 fixed YES 2000 2.3 no no
Leica SL (⇒ lft | rgt) 4400 YES 3.0 1040 fixed YES 8000 11.0 no no
Nikon D750 (⇒ lft | rgt) optical YES 3.2 1229 tilting no 4000 6.0 12 no
Nikon D810 (⇒ lft | rgt) optical YES 3.2 1229 fixed no 4000 5.0 12 no
Nikon D4S (⇒ lft | rgt) optical YES 3.2 921 fixed no 8000 11.0 no no
Olympus E-M10 III (⇒ lft | rgt) 2360 no 3.0 1040 tilting YES 4000 8.6 5.8 YES
Olympus E-M10 II (⇒ lft | rgt) 2360 no 3.0 1040 tilting YES 4000 8.0 5.8 YES
Olympus E-M5 II (⇒ lft | rgt) 2360 no 3.0 1037 swivel YES 8000 10.0 no YES
Olympus E-M1 (⇒ lft | rgt) 2360 no 3.0 1037 tilting YES 8000 10.0 no YES
Olympus E-P5 (⇒ lft | rgt) no no 3.0 1037 tilting YES 8000 9.0 7 YES
Pentax 645D (⇒ lft | rgt) optical YES 3.0 921 fixed no 4000 1.1 no no
Sony RX1R II (⇒ lft | rgt) 2360 no 3.0 1229 tilting no 4000 5.0 no no
Sony A7S (⇒ lft | rgt) 2400 no 3.0 921 tilting no 8000 5.0 no no

The 645Z is a current model that online retailers, such as amazon, will have in stock. In contrast, the E-M10 has been discontinued (but it can be found pre-owned on ebay). As a replacement in the same line of cameras, the E-M10 was succeeded by the Olympus E-M10 II.

Summary

So what conclusions can be drawn? Is the Pentax 645Z better than the Olympus E-M10 or vice versa? Below is a summary of the relative strengths of each of the two contestants.


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Advantages of the Pentax 645Z:

  • More detail: Offers more megapixels (51.1 vs 15.9MP) with a 79% higher linear resolution.
  • Better image quality: Scores substantially higher (29 points) in the DXO overall assessment.
  • Richer colors: Generates images with noticeably better colors (3.2 bits more color depth).
  • More dynamic range: Captures a larger spectrum of light and dark details (2.4 EV of extra DR).
  • Better low-light sensitivity: Requires less light for good images (2.3 stops ISO advantage).
  • Better video: Provides higher movie framerates (1080/60i vs 1080/30p).
  • Brighter framing: Features an optical viewfinder for clear, lag-free composition.
  • Easier setting verification: Has an LCD display on top to control shooting parameters.
  • Larger screen: Has a bigger rear LCD (3.2" vs 3.0") for image review and settings control.
  • Longer lasting: Can take more shots (650 versus 320) on a single battery charge.
  • Better sealing: Is weather sealed to enable shooting in dusty or wet environments.

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Arguments in favor of the Olympus OM-D E-M10:

  • More framing info: Has an electronic viewfinder that displays shooting data.
  • Fewer buttons to press: Has a touchscreen to facilitate handling and shooting adjustments.
  • Faster burst: Shoots at higher frequency (8 vs 3 flaps/sec) to capture the decisive moment.
  • More compact: Is smaller (119x82mm vs 156x117mm) and will fit more readily into a bag.
  • Less heavy: Has a lower weight (by 1154g or 74 percent) and is thus easier to take along.
  • More legacy lens friendly: Can use many non-native lenses via adapters.
  • Easier fill-in: Has a small integrated flash to brighten shadows of backlit subjects.
  • Sharper images: Has stabilization technology build-in to reduce the impact of hand-shake.
  • More affordable: Was introduced into a lower priced category (92 percent cheaper at launch).

If the count of individual advantages (bullet points above) is taken as a guide, the 645Z emerges as the winner of the contest (11 : 9 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.

645Z 11:09 E-M10

In any case, while the specs-based evaluation of cameras is instructive in revealing their potential as photographic tools, it says nothing about, for example, the handling, responsiveness, and overall imaging quality of the 645Z and the E-M10 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 hands-on reviews by experts are important. The table below summarizes the assessments of some of the best known camera review sites. The full reviews are available, respectively, at cameralabs.com, dpreview.com, ephotozine.com, imaging-resource.com, and photographyblog.com.

Review scores
Camera camera
labs
dp
review
ephoto
zine
imaging
resource
photography
blog
Camera
Launch
(year)
Launch
Price
(USD)
Street
Price
(amazon)
Used
Price
(ebay)
Pentax 645Z (⇒ rgt) - - 4.5/5 5/5 5/5 2014 8,499 latest check
Olympus E-M10 (⇒ lft) - 80/100 Gold 5/5 4.5/5 5/5 2014 699discont. check
Canon 5DS R (⇒ lft | rgt) Rec 83/100 Silver 5/5 5/5 4.5/5 2015 3,699 latest check
Canon 5DS (⇒ lft | rgt) Rec 83/100 Silver 4.5/5 5/5 4.5/5 2015 3,699 latest check
Hasselblad X1D (⇒ lft | rgt) - - - - 4/5 2016 8,995 latest check
Leica SL (⇒ lft | rgt) - 84/100 4.5/5 4/5 4/5 2015 7,450 latest check
Nikon D750 (⇒ lft | rgt) HiRec 90/100 Gold 4.5/5 5/5 4.5/5 2014 2,299 latest check
Nikon D810 (⇒ lft | rgt) - 86/100 Gold 5/5 4.5/5 4.5/5 2014 3,299discont. check
Nikon D4S (⇒ lft | rgt) - - 4.5/5 5/5 4.5/5 2014 6,499discont. check
Olympus E-M10 III (⇒ lft | rgt) Rec 80/100 4.5/5 .. 4.5/5 2017 649 latest check
Olympus E-M10 II (⇒ lft | rgt) HiRec 80/100 Silver 5/5 5/5 5/5 2015 799discont. check
Olympus E-M5 II (⇒ lft | rgt) HiRec 81/100 Silver 5/5 4.5/5 5/5 2015 1,099 latest check
Olympus E-M1 (⇒ lft | rgt) HiRec 84/100 Gold 4.5/5 4.5/5 4.5/5 2013 1,399discont. check
Olympus E-P5 (⇒ lft | rgt) HiRec 78/100 Silver 4.5/5 4.5/5 5/5 2013 999discont. check
Pentax 645D (⇒ lft | rgt) - - - 4.5/5 - 2010 9,995discont. check
Sony RX1R II (⇒ lft | rgt) - 82/100 Silver - reviewed 4.5/5 2015 3,299 latest check
Sony A7S (⇒ lft | rgt) - 86/100 Gold 4.5/5 4.5/5 5/5 2014 2,499discont. check

Care should be taken when interpreting the review scores above, though. The assessments were made in relation to similar cameras of the same technological generation. Thus, a score needs to be put into the context of the launch date and the launch price of the camera, and comparing ratings of very distinct cameras or ones that are far apart in terms of their release date 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 comparisons

In case you would like to check on the differences and similarities of other camera models, just use the search menu below. An an alternative, you can also directly jump to any one of the listed comparisons that were previously generated by the CAM-parator tool. If you do not see the camera that you are looking for, please contact me, and I will try to update the database with the necessary infos.

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