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Pentax 645Z versus Sony A7R II

The Pentax 645Z and the Sony Alpha A7R II are two digital cameras that were officially introduced, respectively, in April 2014 and June 2015. The 645Z is a DSLR, while the A7R II is a mirrorless interchangeable lens camera. The cameras are based on a medium format (645Z) and a full frame sensor. The Pentax has a resolution of 51.1 megapixel, whereas the Sony provides 42.2 MP.

Body comparison

The physical size and weight of the Pentax 645Z and the Sony A7R II are illustrated in the side-by-side display below. Three consecutive perspectives from the front, the top, and the back are presented. All width, height and depth measures are rounded to the nearest millimeter. You can also use the toggle button 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 – the 645Z – represents 100 percent across all the size and weight measures).

Pentax 645Z vs Sony A7R II front
645Z versus A7R II top view
645Z and A7R II 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 Sony A7R II is notably smaller (33 percent) than the Pentax 645Z. Moreover, the A7R II is substantially lighter (60 percent) than the 645Z. 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 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
Sony A7R II (⇒ lft) 127 mm 96 mm 60 mm 625 g 290 YES 2015 3,199discont. 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
Pentax 645D (⇒ lft | rgt) 156 mm 117 mm 119 mm 1480 g .. YES 2010 9,995discont. check
Sony A7R III (⇒ lft | rgt) 127 mm 96 mm 74 mm 650 g 650 YES 2017 3,199 latest check
Sony A99 II (⇒ lft | rgt) 143 mm 104 mm 76 mm 849 g 490 YES 2016 3,199 latest check
Sony A7S II (⇒ lft | rgt) 127 mm 96 mm 60 mm 627 g 370 YES 2015 2,999 latest check
Sony RX1R II (⇒ lft | rgt) 113 mm 65 mm 72 mm 507 g 220 no 2015 3,299 latest check
Sony A7 II (⇒ lft | rgt) 127 mm 96 mm 60 mm 599 g 350 YES 2014 1,999 latest check
Sony A7S (⇒ lft | rgt) 127 mm 94 mm 48 mm 489 g 380 YES 2014 2,499discont. check
Sony A7R (⇒ lft | rgt) 127 mm 94 mm 48 mm 465 g 340 YES 2013 2,299discont. check

The listed prices provide an indication of the market segment that the manufacturer of the cameras have been targeting. The A7R II was launched at a markedly lower price (by 62 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 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. 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 tend to be more expensive and lead to bigger and heavier cameras and lenses.

Of the two cameras under consideration, the Pentax 645Z features a medium format sensor and the Sony A7R II a full frame sensor. The sensor area in the A7R II is 40 percent smaller. As a result of these sensor size differences, the cameras have a format factor of, respectively, 0.79 and 1.0. The sensor in the 645Z has a native 4:3 aspect ratio, while the one in the A7R II offers a 3:2 aspect.

Pentax 645Z and Sony A7R II sensor measures
Sensor size
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Sensor size

With 51.1MP, the 645Z offers a higher resolution than the A7R II (42.2MP), but the 645Z nevertheless has larger individual pixels (pixel pitch of 5.30μm versus 4.52μm for the A7R II) due to its larger sensor. However, the A7R II is a somewhat more recent model (by 1 year and 1 month) than the 645Z, and its sensor might have benefitted from technological advances during this time that enhance the light gathering capacity of its pixels. 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 A7R II MP
Sensor resolution
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Sensor resolution

Since 2007, DXO Mark has published sensor performance measurements that have been derived using a consistent methodology. 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 image quality. The following table provides an overview of the physical sensor characteristics, as well as the sensor quality measurements for a selection of comparators.

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
Sony A7R II (⇒ lft) Full Frame 42.2 7952 5304 4K/30p 26.0 13.9 3434 98
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
Pentax 645D (⇒ lft | rgt) Medium Format 39.5 7264 5440 no 24.6 12.6 1262 82
Sony A7R III (⇒ lft | rgt) Full Frame 42.2 7952 5304 4K/30p .. .. .. ..
Sony A99 II (⇒ lft | rgt) Full Frame 42.2 7952 5304 4K/30p 25.4 13.4 2317 92
Sony A7S II (⇒ lft | rgt) Full Frame 12.0 4240 2832 4K/30p 23.6 13.3 2993 85
Sony RX1R II (⇒ lft | rgt) Full Frame 42.2 7952 5304 1080/60p 25.8 13.9 3204 97
Sony A7 II (⇒ lft | rgt) Full Frame 24.0 6000 4000 1080/60p 24.9 13.6 2449 90
Sony A7S (⇒ lft | rgt) Full Frame 12.0 4240 2832 1080/60p 23.9 13.2 3702 87
Sony A7R (⇒ lft | rgt) Full Frame 36.2 7360 4912 1080/60p 25.6 14.1 2746 95

Many modern cameras cannot only take still pictures, but also record videos. Both cameras under consideration have a sensor with sufficiently fast read-out times for moving pictures, but the A7R II provides a better video resolution than the 645Z. It can shoot movie footage at 4K/30p, while the Pentax is limited to 1080/60i.

Feature comparison

Apart from body and sensor, cameras can and do differ across a variety of features. For example, the A7R II has an electronic viewfinder (2400k 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 table below summarizes some of the other core capabilities of the Pentax 645Z and Sony A7R II in connection with corresponding information for a sample of similar cameras. If you need more detail on the specs, you can find comprehensive listings, 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
Sony A7R II (⇒ lft) 2400 no 3.0 1229 tilting no 8000 5.0 no 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
Pentax 645D (⇒ lft | rgt) optical YES 3.0 921 fixed no 4000 1.1 no no
Sony A7R III (⇒ lft | rgt) 3686 no 3.0 1440 tilting YES 8000 10.0 no YES
Sony A99 II (⇒ lft | rgt) 2400 YES 3.0 1229 tilting no 8000 12.0 no YES
Sony A7S II (⇒ lft | rgt) 2400 no 3.0 1229 tilting no 8000 5.0 no YES
Sony RX1R II (⇒ lft | rgt) 2360 no 3.0 1229 tilting no 4000 5.0 no no
Sony A7 II (⇒ lft | rgt) 2400 no 3.0 1230 tilting no 8000 5.0 no YES
Sony A7S (⇒ lft | rgt) 2400 no 3.0 921 tilting no 8000 5.0 no no
Sony A7R (⇒ lft | rgt) 2400 no 3.0 1230 tilting no 8000 4.0 no no

The 645Z is a current model that online retailers, such as amazon, will have in stock. In contrast, the A7R II has been discontinued (but it can be found pre-owned on ebay). As a replacement in the same line of cameras, the A7R II was succeeded by the Sony Alpha A7R III.

Summary

So what is the bottom line? Is there a clear favorite between the Pentax 645Z and the Pentax 645Z? The listing below highlights the relative strengths of the two models.


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Arguments in favor of the Pentax 645Z:

  • More detail: Offers more megapixels (51.1 vs 42.2MP) with a 8% higher linear resolution.
  • More dynamic range: Captures a larger spectrum of light and dark details (0.8 EV of extra DR).
  • Better low-light sensitivity: Requires less light for good images (0.4 stops ISO advantage).
  • 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 290) on a single battery charge.
  • More heavily discounted: Has been on the market for longer (launched in April 2014).

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Reasons to prefer the Sony Alpha A7R II:

  • Better video: Provides higher definition movie capture (4K/30p vs 1080/60i).
  • More framing info: Has an electronic viewfinder that displays shooting data.
  • More detailed LCD: Has a higher resolution rear screen (1229k vs 1037k dots).
  • Faster shutter: Has a higher mechanical shutter speed (8000/sec vs 4000/sec) to freeze action.
  • Faster burst: Shoots at higher frequency (5 vs 3 flaps/sec) to capture the decisive moment.
  • More compact: Is smaller (127x96mm vs 156x117mm) and will fit more readily into a bag.
  • Less heavy: Has a lower weight (by 925g or 60 percent) and is thus easier to take along.
  • More legacy lens friendly: Can use many non-native lenses via adapters.
  • Sharper images: Has stabilization technology build-in to reduce the impact of hand-shake.
  • More affordable: Was introduced into a lower priced category (62 percent cheaper at launch).
  • More modern: Was introduced somewhat (1 year and 1 month) more recently.

If the count of individual advantages (bullet points above) is taken as a guide, the A7R II emerges as the winner of the match-up (11 : 8 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.

645Z 08:11 A7R II

In any case, while the comparison of the spec-sheets of cameras can offer a general idea of their imaging potential, it remains partial and cannot reveal, for example, the handling experience and imaging performance when actually working with the 645Z or the A7R II. 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 detailed reviews can be accessed, respectively, on the websites of 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
Sony A7R II (⇒ lft) HiRec 90/100 Gold 5/5 4.5/5 5/5 2015 3,199discont. 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
Pentax 645D (⇒ lft | rgt) - - - 4.5/5 - 2010 9,995discont. check
Sony A7R III (⇒ lft | rgt) .. 90/100 Gold .. .. .. 2017 3,199 latest check
Sony A99 II (⇒ lft | rgt) - 85/100 Silver 4.5/5 4.5/5 4.5/5 2016 3,199 latest check
Sony A7S II (⇒ lft | rgt) Rec - 4.5/5 5/5 5/5 2015 2,999 latest check
Sony RX1R II (⇒ lft | rgt) - 82/100 Silver - reviewed 4.5/5 2015 3,299 latest check
Sony A7 II (⇒ lft | rgt) Rec 82/100 Silver 4.5/5 5/5 5/5 2014 1,999 latest check
Sony A7S (⇒ lft | rgt) - 86/100 Gold 4.5/5 4.5/5 5/5 2014 2,499discont. check
Sony A7R (⇒ lft | rgt) HiRec 82/100 Gold 4.5/5 5/5 5/5 2013 2,299discont. check

Care should be taken when interpreting the review scores above, though. The ratings are only valid when refering to cameras in the same category and of the same age. Thus, a score needs to be put into the context of the launch date and the launch price 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 comparisons

If you would like to see a different side-by-side camera review, just make a corresponding selection in the search boxes 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 cannot find the camera you are interested in, please send me an email, and I will try to locate and add the respective data to the application.

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