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Sony RX10 IV versus Pentax 645Z

The Sony Cyber-shot DSC-RX10 IV and the Pentax 645Z are two digital cameras that were announced, respectively, in September 2017 and April 2014. The RX10 IV is a fixed lens compact, while the 645Z is a DSLR. The cameras are based on an one-inch (RX10 IV) and a medium format (645Z) sensor. The Sony has a resolution of 20 megapixel, whereas the Pentax provides 51.1 MP. Read on to find out how these two cameras compare with respect to their size, their sensors, their features, and their reception by expert reviewers.

Body comparison: Sony RX10 IV vs Pentax 645Z

The physical size and weight of the Sony RX10 IV and the Pentax 645Z are illustrated in the side-by-side display below. Three consecutive views from the front, the top, and the rear side are shown. All width, height and depth dimensions are rounded to the nearest millimeter. If you prefer, you can also use the toggle button to switch to a comparison in percentage terms (in this case, the camera on the left side – the RX10 IV – represents the basis for the calculations across all the size and weight measures).

Compare Sony RX10 IV vs Pentax 645Z
RX10 IV versus 645Z top view
RX10 IV and 645Z rear side
Body view (RX10 IV on the left)

If the front view area (width x height) of the cameras is taken as an aggregate measure of their size, the Pentax 645Z is considerably larger (46 percent) than the Sony RX10 IV. 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 and possibly misleading, as the RX10 IV has a lens build in, whereas the 645Z is an interchangeable lens camera that requires a separate lens. Attaching the latter will add extra weight and bulk to the setup.

Concerning battery life, the RX10 IV gets 400 shots out of its NP-FW50 battery, while the 645Z can take 650 images on a single charge of its D-LI90 power pack.

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 camera 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)
Sony RX10 IV (⇒ rgt) 133 mm 94 mm 145 mm 1095 g 400 YES 2017 1,699 latest check
Pentax 645Z (⇒ lft) 156 mm 117 mm 123 mm 1550 g 650 YES 2014 8,499 latest check
Canon G1 X Mark III (⇒ lft | rgt) 115 mm 78 mm 51 mm 399 g 200 YES 2017 1,299 latest 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
Fujifilm X-Pro2 (⇒ lft | rgt) 141 mm 83 mm 46 mm 495 g 350 YES 2016 1,699 latest check
Fujifilm X-T2 (⇒ lft | rgt) 133 mm 92 mm 49 mm 507 g 340 YES 2016 1,599 latest check
Leica SL (⇒ lft | rgt) 147 mm 104 mm 39 mm 847 g 400 YES 2015 7,450 latest check
Nikon D500 (⇒ lft | rgt) 147 mm 115 mm 81 mm 860 g 1240 YES 2016 1,999 latest check
Nikon D750 (⇒ lft | rgt) 141 mm 113 mm 78 mm 750 g 1230 YES 2014 2,299 latest check
Pentax 645D (⇒ lft | rgt) 156 mm 117 mm 119 mm 1480 g 800 YES 2010 9,995discont. check
Sony A6300 (⇒ lft | rgt) 120 mm 67 mm 49 mm 404 g 400 YES 2016 999discont. check
Sony A6500 (⇒ lft | rgt) 120 mm 67 mm 53 mm 453 g 350 YES 2016 1,399 latest check
Sony RX10 III (⇒ lft | rgt) 133 mm 94 mm 127 mm 1051 g 420 YES 2016 1,499discont. check
Sony RX100 V (⇒ lft | rgt) 102 mm 58 mm 41 mm 299 g 220 no 2016 999 latest check
Sony RX10 II (⇒ lft | rgt) 129 mm 88 mm 102 mm 813 g 400 YES 2015 1,299discont. check
Sony RX10 (⇒ lft | rgt) 129 mm 88 mm 102 mm 813 g 420 YES 2013 1,299discont. check

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 RX10 IV was launched at a lower price than the 645Z, despite having a lens build in. 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: Sony RX10 IV vs Pentax 645Z

The size of the imaging sensor is a crucial determinant 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 tend to be more expensive and lead to bigger and heavier cameras and lenses.

Of the two cameras under consideration, the Sony RX10 IV features an one-inch sensor and the Pentax 645Z a medium format sensor. The sensor area in the 645Z is 1139 percent bigger. As a result of these sensor size differences, the cameras have a format factor of, respectively, 2.7 and 0.79. The sensor in the RX10 IV has a native 3:2 aspect ratio, while the one in the 645Z offers a 4:3 aspect.

Sony RX10 IV and Pentax 645Z sensor measures
Sensor size

With 51.1MP, the 645Z offers a higher resolution than the RX10 IV (20MP), but the 645Z nevertheless has larger individual pixels (pixel pitch of 5.30μm versus 2.41μm for the RX10 IV) due to its larger sensor. However, the RX10 IV is a much more recent model (by 3 years and 4 months) than the 645Z, 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 645Z has no anti-alias filter installed, so that it can capture all the detail its sensor resolves.

RX10 IV versus 645Z MP
Sensor resolution

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 table below summarizes the physical sensor characteristics and sensor quality findings and compares them across a set of similar cameras.

Sensor Characteristics
Camera Sensor
Class
Resolution
(Megapixel)
Horiz.
Pixels
Vert.
Pixels
Video
Format
DXO
Portrait
DXO
Landscape
DXO
Sports
DXO
Overall
Sony RX10 IV (⇒ rgt) 1-inch 20.0 5472 3648 4K/30p .. .. .. ..
Pentax 645Z (⇒ lft) Medium Format 51.1 8256 6192 1080/60i 26.0 14.7 4505 101
Canon G1 X Mark III (⇒ lft | rgt) APS-C 24.0 6000 4000 1080/60p .. .. .. ..
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
Fujifilm X-Pro2 (⇒ lft | rgt) APS-C 24.0 6000 4000 1080/60p - - - -
Fujifilm X-T2 (⇒ lft | rgt) APS-C 24.0 6000 4000 4K/30p - - - -
Leica SL (⇒ lft | rgt) Full Frame 24.0 6000 4000 4K/30p 25.0 13.4 1821 88
Nikon D500 (⇒ lft | rgt) APS-C 20.7 5568 3712 4K/30p 24.0 14.0 1324 83
Nikon D750 (⇒ lft | rgt) Full Frame 24.2 6016 4016 1080/60p 24.8 14.5 2956 93
Pentax 645D (⇒ lft | rgt) Medium Format 39.5 7264 5440 no 24.6 12.6 1262 82
Sony A6300 (⇒ lft | rgt) APS-C 24.0 6000 4000 4K/30p 24.4 13.7 1437 85
Sony A6500 (⇒ lft | rgt) APS-C 24.0 6000 4000 4K/30p 24.5 13.7 1405 85
Sony RX10 III (⇒ lft | rgt) 1-inch 20.0 5472 3648 4K/30p 23.1 12.6 472 70
Sony RX100 V (⇒ lft | rgt) 1-inch 20.0 5472 3648 4K/30p 22.8 12.4 586 70
Sony RX10 II (⇒ lft | rgt) 1-inch 20.0 5472 3648 4K/30p 23.0 12.6 531 70
Sony RX10 (⇒ lft | rgt) 1-inch 20.0 5472 3648 1080/60p 22.9 12.6 474 69

Many modern cameras are not only capable of taking still images, but can also record movies. Both cameras under consideration are equipped with sensors that have a sufficiently high read-out speed for moving images, but the RX10 IV provides a higher video resolution than the 645Z. It can shoot video footage at 4K/30p, while the Pentax is limited to 1080/60i.

Feature comparison: Sony RX10 IV vs Pentax 645Z

Apart from body and sensor, cameras can and do differ across a variety of features. For example, the RX10 IV has an electronic viewfinder (2359k 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 following table reports on some other key feature differences and similarities of the Sony RX10 IV, the Pentax 645Z, and comparable cameras. If needed, the dpreview camera hub, for example, contains further detail on the cameras' specs.

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
Sony RX10 IV (⇒ rgt) 2359 YES 3.0 1440 tilting YES 2000 24.0 10.8 YES
Pentax 645Z (⇒ lft) optical YES 3.2 1037 tilting no 4000 3.0 no no
Canon G1 X Mark III (⇒ lft | rgt) 2360 no 3.0 1040 swivel YES 2000 9.0 9 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
Fujifilm X-Pro2 (⇒ lft | rgt) 2360 no 3.0 1620 fixed no 8000 8.0 no no
Fujifilm X-T2 (⇒ lft | rgt) 2360 no 3.0 1040 tilting no 8000 14.0 no no
Leica SL (⇒ lft | rgt) 4400 YES 3.0 1040 fixed YES 8000 11.0 no no
Nikon D500 (⇒ lft | rgt) optical YES 3.2 2359 tilting YES 8000 10.0 no no
Nikon D750 (⇒ lft | rgt) optical YES 3.2 1229 tilting no 4000 6.0 12 no
Pentax 645D (⇒ lft | rgt) optical YES 3.0 921 fixed no 4000 1.1 no no
Sony A6300 (⇒ lft | rgt) 2300 no 3.0 922 tilting no 4000 11.0 6 no
Sony A6500 (⇒ lft | rgt) 2300 no 3.0 922 tilting YES 4000 11.0 6 YES
Sony RX10 III (⇒ lft | rgt) 2359 YES 3.0 1229 tilting no 2000 14.0 10.8 YES
Sony RX100 V (⇒ lft | rgt) 2359 no 3.0 1229 tilting no 2000 24.0 10.2 YES
Sony RX10 II (⇒ lft | rgt) 2359 YES 3.0 1229 tilting no 3200 14.0 10.2 YES
Sony RX10 (⇒ lft | rgt) 1440 YES 3.0 1229 tilting no 3200 10.0 10.2 YES

Both the RX10 IV and the 645Z are current models that good online retailers will have in stock. You can check the latest prices, for example, at amazon. The 645Z replaced the earlier Pentax 645D, while the RX10 IV followed on from the Sony RX10 III.

Review summary: Sony RX10 IV vs Pentax 645Z

So what is the bottom line? Is there a clear favorite between the Sony RX10 IV and the Pentax 645Z? A synthesis of the relative strong points of each of the models is listed below.


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Reasons to prefer the Sony Cyber-shot DSC-RX10 IV:

  • Better moiré control: Has an anti-alias filter to avoid artificial patterns to appear in images.
  • 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 (1440k vs 1037k dots).
  • Fewer buttons to press: Is equipped with a touch-sensitive rear screen to facilitate handling.
  • Faster burst: Shoots at higher frequency (24 vs 3 flaps/sec) to capture the decisive moment.
  • Ready to shoot: Comes with a build-in lens, while the 645Z requires a separate lens.
  • More compact: Is smaller (133x94mm vs 156x117mm) and thus needs less room in the bag.
  • Less heavy: Is lighter even though it comes with a build-in lens (unlike the 645Z).
  • Easier fill-in: Is equipped with a small onboard flash to brighten deep shadow areas.
  • Sharper images: Has hand-shake reducing image stabilization build-in.
  • More affordable: Was introduced at a lower price, despite coming with a build-in lens.
  • More modern: Reflects 3 years and 4 months of technical progress since the 645Z launch.

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Arguments in favor of the Pentax 645Z:

  • More detail: Has more megapixels (51.1 vs 20MP), which boosts linear resolution by 57%.
  • Maximized detail: Lacks an anti-alias filter to exploit the sensor's full resolution potential.
  • Brighter framing: Features an optical viewfinder for clear, lag-free composition.
  • Larger screen: Has a bigger rear LCD (3.2" vs 3.0") for image review and settings control.
  • Faster shutter: Has higher mechanical shutter speed (4000/sec vs 2000/sec) to freeze action.
  • More flexible: Makes it possible to change lenses and thus to use specialty optics.
  • Longer lasting: Gets more shots (650 versus 400) out of a single battery charge.
  • More heavily discounted: Has been around for much longer (launched in April 2014).

If the count of individual advantages (bullet points above) is taken as a guide, the RX10 IV is the clear winner of the match-up (13 : 8 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.

RX10 IV 13:08 645Z

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 RX10 IV and the 645Z in practical situations. At times, user reviews, such as those published at amazon, address these issues in a useful manner, but such feedback is on many occasions incomplete, inconsistent, and unreliable. This is where reviews by experts come in. The table below summarizes the assessments of some of the best known camera review sites. You can find the full text of the reviews, respectively, at cameralabs.com, dpreview.com, ephotozine.com, imaging-resource.com, and photographyblog.com.

Review scores
Camera camera
labs
.com
dp
review
.com
ephoto
zine
.com
imaging
resource
.com
photography
blog
.com
Camera
Launch
(year)
Launch
Price
(USD)
Street
Price
(amazon)
Used
Price
(ebay)
Sony RX10 IV (⇒ rgt) Rec 84/100 Gold 4.5/5 .. 5/5 2017 1,699 latest check
Pentax 645Z (⇒ lft) - - 4.5/5 5/5 5/5 2014 8,499 latest check
Canon G1 X Mark III (⇒ lft | rgt) Rec 79/100 4.5/5 .. 4.5/5 2017 1,299 latest 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
Fujifilm X-Pro2 (⇒ lft | rgt) Rec 83/100 Silver 4.5/5 4.5/5 4.5/5 2016 1,699 latest check
Fujifilm X-T2 (⇒ lft | rgt) HiRec 86/100 Gold 4.5/5 5/5 5/5 2016 1,599 latest check
Leica SL (⇒ lft | rgt) - 84/100 4.5/5 4/5 4/5 2015 7,450 latest check
Nikon D500 (⇒ lft | rgt) HiRec 91/100 Gold 4.5/5 5/5 5/5 2016 1,999 latest check
Nikon D750 (⇒ lft | rgt) HiRec 90/100 Gold 4.5/5 5/5 4.5/5 2014 2,299 latest check
Pentax 645D (⇒ lft | rgt) - - - 4.5/5 - 2010 9,995discont. check
Sony A6300 (⇒ lft | rgt) Rec 85/100 Gold 5/5 5/5 5/5 2016 999discont. check
Sony A6500 (⇒ lft | rgt) HiRec 85/100 Silver 4.5/5 5/5 4.5/5 2016 1,399 latest check
Sony RX10 III (⇒ lft | rgt) Rec 84/100 Silver 4.5/5 4.5/5 4.5/5 2016 1,499discont. check
Sony RX100 V (⇒ lft | rgt) HiRec 83/100 Silver 4/5 5/5 4.5/5 2016 999 latest check
Sony RX10 II (⇒ lft | rgt) HiRec 82/100 Gold 4.5/5 4.5/5 4/5 2015 1,299discont. check
Sony RX10 (⇒ lft | rgt) Rec 80/100 Gold 4.5/5 4.5/5 4.5/5 2013 1,299discont. 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. 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 would like to check on the differences and similarities of other camera models, just make your choice using the following search menu. Alternatively, you can follow any of the listed hyperlinks for comparisons that others found interesting. 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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