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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 officially introduced, 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

An illustration of the physical size and weight of the Sony RX10 IV and the Pentax 645Z is provided in the side-by-side display below. The two cameras are presented according to their relative size. 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. 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 – the RX10 IV – represents the basis or 100 percent across all the size and weight measures).

Compare Sony RX10 IV vs Pentax 645Z
Compare RX10 IV versus 645Z top
Compare RX10 IV and 645Z rear

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 adjacent table lists the principal physical characteristics of the two cameras alongside a wider set of alternatives. If you would like to visualize and compare a different camera combination, just use the right or left arrows in the table to switch to the respective camera. Alternatively, you can also navigate to the CAM-parator app and make your selection from the full list of cameras there.

Camera Body Specifications
  Camera
Model
Camera
Width
Camera
Height
Camera
Depth
Camera
Weight
Battery
Life
(CIPA)
Weather
Sealing
(yes/no)
Camera
Launch
(announced)
Launch
Price
(USD)
Street
Price
(USD)
Used
Price
(USD)
Camera
Model
Sony RX10 IV» 5.2 in 3.7 in 5.7 in 38.6 oz 400 Y Sep 2017 1,699 i i Sony RX10 IV
Pentax 645Z« 6.1 in 4.6 in 4.8 in 54.7 oz 650 Y Apr 2014 8,499 i i Pentax 645Z
Canon G1 X Mark III« » 4.5 in 3.1 in 2.0 in 14.1 oz 200 Y Oct 2017 1,299 i i Canon G1 X Mark III
Canon 5DS R« » 6.0 in 4.6 in 3.0 in 32.8 oz 700 Y Feb 2015 3,699 i i Canon 5DS R
Canon 5DS« » 6.0 in 4.6 in 3.0 in 32.8 oz 700 Y Feb 2015 3,699 i i Canon 5DS
Fujifilm X-Pro2« » 5.6 in 3.3 in 1.8 in 17.5 oz 350 Y Jan 2016 1,699 i i Fujifilm X-Pro2
Fujifilm X-T2« » 5.2 in 3.6 in 1.9 in 17.9 oz 340 Y Jul 2016 1,599 i i Fujifilm X-T2
Leica SL« » 5.8 in 4.1 in 1.5 in 29.9 oz 400 Y Oct 2015 7,450 i i Leica SL
Nikon D500« » 5.8 in 4.5 in 3.2 in 30.3 oz 1240 Y Jan 2016 1,999 i i Nikon D500
Nikon D750« » 5.6 in 4.4 in 3.1 in 26.5 oz 1230 Y Sep 2014 2,299 i i Nikon D750
Pentax 645D« » 6.1 in 4.6 in 4.7 in 52.2 oz 800 Y Mar 2010 9,995- i Pentax 645D
Sony A6300« » 4.7 in 2.6 in 1.9 in 14.3 oz 400 Y Feb 2016 999- i Sony A6300
Sony A6500« » 4.7 in 2.6 in 2.1 in 16.0 oz 350 Y Oct 2016 1,399 i i Sony A6500
Sony RX10 III« » 5.2 in 3.7 in 5.0 in 37.1 oz 420 Y Mar 2016 1,499- i Sony RX10 III
Sony RX100 V« » 4.0 in 2.3 in 1.6 in 10.5 oz 220 n Oct 2016 999 i i Sony RX100 V
Sony RX10 II« » 5.1 in 3.5 in 4.0 in 28.7 oz 400 Y Jun 2015 1,299- i Sony RX10 II
Sony RX10« » 5.1 in 3.5 in 4.0 in 28.7 oz 420 Y Oct 2013 1,299- i Sony RX10

Any camera purchase will naturally be influenced heavily by the price. The manufacturer’s suggested retail prices give an idea on the placement of the camera in the maker’s lineup and the broader market. 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 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 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. Moreover, a large sensor camera will give the photographer more control over depth-of-field in the image and, thus, the ability to better isolate a subject from the 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 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

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

Consistent information on actual sensor performance is available from DXO Mark for many cameras. 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
Model
Sensor
Class
Resolution
(MP)
Horiz.
Pixels
Vert.
Pixels
Video
Format
DXO
Portrait
DXO
Landscape
DXO
Sports
DXO
Overall
Camera
Model
Sony RX10 IV» 1-inch 20.0 5472 36484K/30p----Sony RX10 IV
Pentax 645Z« Medium Format 51.1 8256 61921080/60i26.014.74505101Pentax 645Z
Canon G1 X Mark III« » APS-C 24.0 6000 40001080/60p----Canon G1 X Mark III
Canon 5DS R« » Full Frame 50.3 8688 57921080/60p24.612.4230886Canon 5DS R
Canon 5DS« » Full Frame 50.3 8688 57921080/60p24.712.4238187Canon 5DS
Fujifilm X-Pro2« » APS-C 24.0 6000 40001080/60p----Fujifilm X-Pro2
Fujifilm X-T2« » APS-C 24.0 6000 40004K/30p----Fujifilm X-T2
Leica SL« » Full Frame 24.0 6000 40004K/30p25.013.4182188Leica SL
Nikon D500« » APS-C 20.7 5568 37124K/30p24.014.0132483Nikon D500
Nikon D750« » Full Frame 24.2 6016 40161080/60p24.814.5295693Nikon D750
Pentax 645D« » Medium Format 39.5 7264 5440-24.612.6126282Pentax 645D
Sony A6300« » APS-C 24.0 6000 40004K/30p24.413.7143785Sony A6300
Sony A6500« » APS-C 24.0 6000 40004K/30p24.513.7140585Sony A6500
Sony RX10 III« » 1-inch 20.0 5472 36484K/30p23.112.647270Sony RX10 III
Sony RX100 V« » 1-inch 20.0 5472 36484K/30p22.812.458670Sony RX100 V
Sony RX10 II« » 1-inch 20.0 5472 36484K/30p23.012.653170Sony RX10 II
Sony RX10« » 1-inch 20.0 5472 36481080/60p22.912.647469Sony RX10

Many modern cameras are not only capable of taking still images, but also of capturing video footage. 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

Beyond body and sensor, cameras can and do differ across a range 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 you need more detail on the specs, you can find comprehensive listings, for example, in the dpreview camera hub.

Core Features
  Camera
Model
Viewfinder
(Type or
'000 dots)
Control
Panel
(yes/no)
LCD
Size
(inch)
LCD
Resolution
('000 dots)
LCD
Attach-
ment
Touch
Screen
(yes/no)
Shutter
speed
(1/sec)
Shutter
flaps
(1/sec))
Build-in
Flash
(yes/no)
Build-in
Image
Stab
Camera
Model
Sony RX10 IV»2359 Y 3.0 1440 tilting Y 2000 24.0 Y Y Sony RX10 IV
Pentax 645Z«optical Y 3.2 1037 tilting n 4000 3.0 n n Pentax 645Z
Canon G1 X Mark III« »2360 n 3.0 1040 swivel Y 2000 9.0 Y Y Canon G1 X Mark III
Canon 5DS R« »optical Y 3.2 1040 fixed n 8000 5.0 n n Canon 5DS R
Canon 5DS« »optical Y 3.2 1040 fixed n 8000 5.0 n n Canon 5DS
Fujifilm X-Pro2« »2360 n 3.0 1620 fixed n 8000 8.0 n n Fujifilm X-Pro2
Fujifilm X-T2« »2360 n 3.0 1040 tilting n 8000 14.0 n n Fujifilm X-T2
Leica SL« »4400 Y 3.0 1040 fixed Y 8000 11.0 n n Leica SL
Nikon D500« »optical Y 3.2 2359 tilting Y 8000 10.0 n n Nikon D500
Nikon D750« »optical Y 3.2 1229 tilting n 4000 6.0 Y n Nikon D750
Pentax 645D« »optical Y 3.0 921 fixed n 4000 1.1 n n Pentax 645D
Sony A6300« »2300 n 3.0 922 tilting n 4000 11.0 Y n Sony A6300
Sony A6500« »2300 n 3.0 922 tilting Y 4000 11.0 Y Y Sony A6500
Sony RX10 III« »2359 Y 3.0 1229 tilting n 2000 14.0 Y Y Sony RX10 III
Sony RX100 V« »2359 n 3.0 1229 tilting n 2000 24.0 Y Y Sony RX100 V
Sony RX10 II« »2359 Y 3.0 1229 tilting n 3200 14.0 Y Y Sony RX10 II
Sony RX10« »1440 Y 3.0 1229 tilting n 3200 10.0 Y Y Sony RX10

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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Arguments in favor of 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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Reasons to prefer 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 number of relative strengths (bullet points above) is taken as a guide, the RX10 IV is the clear winner of the match-up (13 : 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 before making a decision on a new camera.

RX10 IV 13:08 645Z

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 RX10 IV or the 645Z. 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 hands-on reviews by experts are important. The following table reports the overall rankings of the cameras as published by some of the major camera review sites (cameralabs, dpreview, ephotozine, imaging-resource, photographyblog). The detailed reviews can be accessed by clicking on the site logo in the table header.

Review Scores
  Camera
Model
cameralabs dpreview ephotozine imaging-resource photographyblog Camera
Launch
(announced)
Launch
Price
(USD)
Street
Price
(USD)
Used
Price
(USD)
Camera
Model
Sony RX10 IV»Rec84/1004.5/5-5/5 Sep 2017 1,699 i i Sony RX10 IV
Pentax 645Z«--4.5/55/55/5 Apr 2014 8,499 i i Pentax 645Z
Canon G1 X Mark III« »Rec79/1004.5/5-4.5/5 Oct 2017 1,299 i i Canon G1 X Mark III
Canon 5DS R« »Rec83/1005/55/54.5/5 Feb 2015 3,699 i i Canon 5DS R
Canon 5DS« »Rec83/1004.5/55/54.5/5 Feb 2015 3,699 i i Canon 5DS
Fujifilm X-Pro2« »Rec83/1004.5/54.5/54.5/5 Jan 2016 1,699 i i Fujifilm X-Pro2
Fujifilm X-T2« »HiRec86/1004.5/55/55/5 Jul 2016 1,599 i i Fujifilm X-T2
Leica SL« »-84/1004.5/54/54/5 Oct 2015 7,450 i i Leica SL
Nikon D500« »HiRec91/1004.5/55/55/5 Jan 2016 1,999 i i Nikon D500
Nikon D750« »HiRec90/1004.5/55/54.5/5 Sep 2014 2,299 i i Nikon D750
Pentax 645D« »---4.5/5- Mar 2010 9,995- i Pentax 645D
Sony A6300« »Rec85/1005/55/55/5 Feb 2016 999- i Sony A6300
Sony A6500« »HiRec85/1004.5/55/54.5/5 Oct 2016 1,399 i i Sony A6500
Sony RX10 III« »Rec84/1004.5/54.5/54.5/5 Mar 2016 1,499- i Sony RX10 III
Sony RX100 V« »HiRec83/1004/55/54.5/5 Oct 2016 999 i i Sony RX100 V
Sony RX10 II« »HiRec82/1004.5/54.5/54/5 Jun 2015 1,299- i Sony RX10 II
Sony RX10« »Rec80/1004.5/54.5/54.5/5 Oct 2013 1,299- i Sony RX10

The above review scores should be interpreted with care, 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 rating-comparisons among cameras that span long time periods or concern very differently equipped models make little sense. It should also be noted that some of the review sites have over time altered the way they render their verdicts.

 

Other camera comparisons

Did this review help to inform your camera decision process? If you would like to see a different side-by-side camera review, just make a corresponding selection in the search boxes below. 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, kindly get in touch, and I will try to add information on that model to the database.

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