Pentax 645Z vs Sony A7R IV
The Pentax 645Z and the Sony Alpha A7R IV are two digital cameras that were officially introduced, respectively, in April 2014 and July 2019. The 645Z is a DSLR, while the A7R IV is a mirrorless interchangeable lens camera. The cameras are based on a medium format (645Z) and a full frame (A7R IV) sensor. The Pentax has a resolution of 51.1 megapixels, whereas the Sony provides 60.2 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 Pentax 645Z and the Sony Alpha A7R IV? 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 Pentax 645Z and the Sony A7R IV. 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.
If the front view area (width x height) of the cameras is taken as an aggregate measure of their size, the Sony A7R IV is considerably smaller (32 percent) than the Pentax 645Z. Moreover, the A7R IV is substantially lighter (57 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 and compare the specifications of available lenses in order to get the full picture of the size and weight of the two camera systems.
Concerning battery life, the 645Z gets 650 shots out of its D-LI90 battery, while the A7R IV can take 670 images on a single charge of its NP-FZ100 power pack. The power pack in the A7R IV can be charged via the USB port, which can be very convenient when travelling.
The adjacent table lists the principal physical characteristics of the two cameras alongside a wider set of alternatives. 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.||Pentax 645Z||156 mm||117 mm||123 mm||1550 g||650||Y||Apr 2014||8,499|
|2.||Sony A7R IV||129 mm||96 mm||78 mm||665 g||670||Y||Jul 2019||3,499|
|3.||Canon 1D X Mark II||158 mm||168 mm||83 mm||1530 g||1210||Y||Feb 2016||5,999|
|4.||Canon 5DS||152 mm||116 mm||76 mm||930 g||700||Y||Feb 2015||3,699|
|5.||Canon 5DS R||152 mm||116 mm||76 mm||930 g||700||Y||Feb 2015||3,699|
|6.||Hasselblad X1D||150 mm||98 mm||71 mm||725 g||..||Y||Jun 2016||8,995|
|7.||Leica SL||147 mm||104 mm||39 mm||847 g||400||Y||Oct 2015||7,450|
|8.||Nikon D850||146 mm||124 mm||79 mm||1005 g||1840||Y||Jul 2017||3,299|
|9.||Nikon D5||160 mm||159 mm||92 mm||1415 g||3780||Y||Jan 2016||6,499|
|10.||Nikon D7200||136 mm||107 mm||76 mm||765 g||1110||Y||Mar 2015||1,199|
|11.||Nikon D4S||160 mm||157 mm||91 mm||1350 g||3020||Y||Feb 2014||6,499|
|12.||Pentax 645D||156 mm||117 mm||119 mm||1480 g||800||Y||Mar 2010||9,995|
|13.||Sony A7S III||127 mm||97 mm||81 mm||699 g||600||Y||Jul 2020||3,499|
|14.||Sony A7R III||127 mm||96 mm||74 mm||650 g||650||Y||Oct 2017||3,199|
|15.||Sony A9||127 mm||96 mm||63 mm||673 g||650||Y||Apr 2017||4,499|
|16.||Sony A7R II||127 mm||96 mm||60 mm||625 g||290||Y||Jun 2015||3,199|
|17.||Sony A7S II||127 mm||96 mm||60 mm||627 g||370||Y||Sep 2015||2,999|
|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 A7R IV was launched at a markedly lower price (by 59 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.
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. 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 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 IV a full frame sensor. The sensor area in the A7R IV is 41 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 IV offers a 3:2 aspect.
Despite having a smaller sensor, the A7R IV offers a higher resolution of 60.2 megapixels, compared with 51.1 MP of the 645Z. This megapixels advantage comes at the cost of a higher pixel density and a smaller size of the individual pixel (with a pixel pitch of 3.76μm versus 5.30μm for the 645Z). However, it should be noted that the A7R IV is much more recent (by 5 years and 3 months) than the 645Z, and its sensor will have benefitted from technological advances during this time that make it possible to gather light more efficiently. 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 Sony A7R IV implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the A7R IV for good quality output (200 dots per inch) amounts to 47.5 x 31.7 inches or 120.7 x 80.5 cm, for very good quality (250 dpi) 38 x 25.3 inches or 96.6 x 64.4 cm, and for excellent quality (300 dpi) 31.7 x 21.1 inches or 80.5 x 53.6 cm. The corresponding values for the Pentax 645Z are 41.3 x 31 inches or 104.9 x 78.6 cm for good quality, 33 x 24.8 inches or 83.9 x 62.9 cm for very good quality, and 27.5 x 20.6 inches or 69.9 x 52.4 cm for excellent quality prints.
The A7R IV has on-sensor phase detect pixels, which results in fast and reliable autofocus acquisition even during live view operation.
Unlike the 645Z, the A7R IV has the capacity to capture high quality composite images (241MP) by combining multiple shots after shifting its sensor by miniscule distances. This multi-shot, pixel-shift mode is most suitable for photography of stationary objects (landscapes, studio scenes).
The Pentax 645Z has a native sensitivity range from ISO 100 to ISO 204800. The corresponding ISO settings for the Sony Alpha A7R IV are ISO 100 to ISO 32000, with the possibility to increase the ISO range to 50-102400.
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 Overall DXO ratings for the two cameras under consideration are close, suggesting that they provide similar imaging performance. The following table provides an overview of the physical sensor characteristics, as well as the sensor quality measurements for a selection of comparators.
| DXO |
|1.||Pentax 645Z||Medium Format||51.1||8256||6192||1080/60i||26.0||14.7||4505||101|
|2.||Sony A7R IV||Full Frame||60.2||9504||6336||4K/30p||26.0||14.8||3344||99|
|3.||Canon 1D X Mark II||Full Frame||20.0||5472||3648||4K/60p||24.1||13.5||3207||88|
|4.||Canon 5DS||Full Frame||50.3||8688||5792||1080/30p||24.7||12.4||2381||87|
|5.||Canon 5DS R||Full Frame||50.3||8688||5792||1080/30p||24.6||12.4||2308||86|
|6.||Hasselblad X1D||Medium Format||51.3||8272||6200||1080/25p||26.2||14.8||4489||102|
|7.||Leica SL||Full Frame||24.0||6000||4000||4K/30p||25.0||13.4||1821||88|
|8.||Nikon D850||Full Frame||45.4||8256||5504||4K/30p||26.4||14.8||2660||100|
|9.||Nikon D5||Full Frame||20.7||5588||3712||4K/30p||25.1||12.3||2343||88|
|11.||Nikon D4S||Full Frame||16.2||4928||3280||1080/60p||24.4||13.3||3074||89|
|12.||Pentax 645D||Medium Format||39.5||7264||5440||none||24.6||12.6||1262||82|
|13.||Sony A7S III||Full Frame||12.0||4240||2832||4K/120p||23.7||13.9||2520||86|
|14.||Sony A7R III||Full Frame||42.2||7952||5304||4K/30p||26.0||14.7||3523||100|
|15.||Sony A9||Full Frame||24.0||6000||4000||4K/30p||24.9||13.3||3517||92|
|16.||Sony A7R II||Full Frame||42.2||7952||5304||4K/30p||26.0||13.9||3434||98|
|17.||Sony A7S II||Full Frame||12.0||4240||2832||4K/30p||23.6||13.3||2993||85|
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 A7R IV provides a better video resolution than the 645Z. It can shoot movie footage at 4K/30p, while the Pentax is limited to 1080/60i.
Apart from body and sensor, cameras can and do differ across a variety of features. For example, the A7R IV has an electronic viewfinder (5760k 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 viewfinders of both cameras offer the same magnification (0.78x), but the one in the A7R IV has a wider field of view (100%) than the finder in the 645Z (98%), so that a larger proportion of the captured image is visible. The table below summarizes some of the other core capabilities of the Pentax 645Z and Sony A7R IV in connection with corresponding information for a sample of similar cameras.
|2.||Sony A7R IV||5760||n||3.0||1440||tilting||Y||1/8000s||10.0||n||Y|
|3.||Canon 1D X Mark II||optical||Y||3.2||1620||fixed||Y||1/8000s||16.0||n||n|
|5.||Canon 5DS R||optical||Y||3.2||1040||fixed||n||1/8000s||5.0||n||n|
|13.||Sony A7S III||9440||n||3.0||1440||swivel||Y||1/8000s||10.0||n||Y|
|14.||Sony A7R III||3686||n||3.0||1440||tilting||Y||1/8000s||10.0||n||Y|
|16.||Sony A7R II||2400||n||3.0||1229||tilting||n||1/8000s||5.0||n||Y|
|17.||Sony A7S II||2400||n||3.0||1229||tilting||n||1/8000s||5.0||n||Y|
One feature that is present on the 645Z, but is missing on the A7R IV is a top-level LCD. While being, of course, smaller than the rear screen, the control panel conveys some of the essential shooting information and can be convenient for quick and easy settings verification.
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 A7R IV 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 Pentax 645Z and the Sony A7R IV 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 645Z and the A7R IV write their files to SDXC cards. Both cameras feature dual card slots, which can be very useful in case a memory card fails. The A7R IV supports UHS-II cards (on both slots), while the 645Z can use UHS-I 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 Pentax 645Z and Sony Alpha A7R IV and, in particular, the interfaces the cameras (and selected comparators) provide for accessory control and data transfer.
| WiFi |
| NFC |
|2.||Sony A7R IV||Y||stereo||mono||Y||Y||micro||3.1||Y||Y||Y|
|3.||Canon 1D X Mark II||Y||mono||mono||Y||Y||mini||3.0||-||-||-|
|5.||Canon 5DS R||Y||mono||mono||Y||-||mini||3.0||-||-||-|
|13.||Sony A7S III||Y||stereo||mono||Y||Y||full||3.2||Y||-||Y|
|14.||Sony A7R III||Y||stereo||mono||Y||Y||micro||3.1||Y||Y||Y|
|16.||Sony A7R II||Y||stereo||mono||Y||Y||micro||2.0||Y||Y||-|
|17.||Sony A7S II||Y||stereo||mono||Y||Y||micro||2.0||Y||Y||-|
It is notable that the A7R IV offers wifi support, which can be a very convenient means to transfer image data to an off-camera location. In contrast, the 645Z does not provide wifi capability.
Both cameras feature a PC Sync terminal to control professional strobe lights, which will be appreciated by studio photographers.
Both the 645Z and the A7R IV are recent models that are part of the current product line-up. The 645Z replaced the earlier Pentax 645D, while the A7R IV followed on from the Sony A7R III. Further information on the two cameras (e.g. user guides, manuals), as well as related accessories, can be found on the official Pentax and Sony websites.
So what conclusions can be drawn? Is the Pentax 645Z better than the Sony A7R IV or vice versa? A synthesis of the relative strong points of each of the models is listed below.
Reasons to prefer the Pentax 645Z:
- 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: Features 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.
- More heavily discounted: Has been available for much longer (launched in April 2014).
Advantages of the Sony Alpha A7R IV:
- More detail: Has more megapixels (60.2 vs 51.1MP), which boosts linear resolution by 11%.
- High quality composites: Can combine several shots after pixel-shifting its sensor.
- Better video: Provides higher definition movie capture (4K/30p vs 1080/60i).
- Better live-view autofocus: Features on-sensor phase-detection for more confident autofocus.
- Better sound control: Has a headphone port that enables audio monitoring while recording.
- 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 (1440k vs 1037k dots).
- Fewer buttons to press: Has a touchscreen to facilitate handling and shooting adjustments.
- Faster shutter: Has higher mechanical shutter speed (1/8000s vs 1/4000s) to freeze action.
- Faster burst: Shoots at higher frequency (10 vs 3 flaps/sec) to capture the decisive moment.
- Less disturbing: Has an electronic shutter option for completely silent shooting.
- More compact: Is smaller (129x96mm vs 156x117mm) and will fit more readily into a bag.
- Less heavy: Has a lower weight (by 885g or 57 percent) and is thus easier to take along.
- Easier travel charging: Can be conveniently charged via its USB port.
- Sharper images: Has stabilization technology built-in to reduce the impact of hand-shake.
- More legacy lens friendly: Can use many non-native lenses via adapters.
- Easier file upload: Has wifi built in for automatic backup or image transfer to the web.
- Easier device pairing: Supports NFC for fast wireless image transfer over short distances.
- Easier wireless transfer: Supports Bluetooth for image sharing without cables.
- Faster buffer clearing: Supports a more advanced SD data transfer standard (UHS-II vs UHS-I).
- More affordable: Was introduced into a lower priced category (59 percent cheaper at launch).
- More modern: Reflects 5 years and 3 months of technical progress since the 645Z launch.
If the count of relative strengths (bullet points above) is taken as a measure, the A7R IV is the clear winner of the contest (24 : 5 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 Pentax 645Z and the Sony A7R IV place the cameras among the top in their class? Find out in the latest Best DSLR Camera and Best Mirrorless Interchangeable Lens Camera listings whether the two cameras rank among the cream of the crop.
In any case, while the specs-based evaluation of cameras can be instructive in revealing their potential as photographic tools, it says little about, for example, the shooting experience and imaging performance of the 645Z and the A7R IV 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 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.||Pentax 645Z||5/5||..||..||4.5/5||5/5||Apr 2014||8,499|
|2.||Sony A7R IV||5/5||+||91/100||4.5/5||5/5||Jul 2019||3,499|
|3.||Canon 1D X Mark II||..||..||89/100||4.5/5||4.5/5||Feb 2016||5,999|
|4.||Canon 5DS||..||+||83/100||4.5/5||4.5/5||Feb 2015||3,699|
|5.||Canon 5DS R||5/5||+||83/100||5/5||4.5/5||Feb 2015||3,699|
|6.||Hasselblad X1D||..||o||81/100||..||4/5||Jun 2016||8,995|
|7.||Leica SL||4/5||..||84/100||4.5/5||4/5||Oct 2015||7,450|
|8.||Nikon D850||4.5/5||+ +||89/100||4.5/5||5/5||Jul 2017||3,299|
|9.||Nikon D5||..||..||89/100||4.5/5||5/5||Jan 2016||6,499|
|10.||Nikon D7200||4/5||+ +||84/100||4.5/5||4.5/5||Mar 2015||1,199|
|11.||Nikon D4S||5/5||..||..||4.5/5||4.5/5||Feb 2014||6,499|
|12.||Pentax 645D||5/5||..||..||..||..||Mar 2010||9,995|
|13.||Sony A7S III||..||+ +||91/100||4.5/5||5/5||Jul 2020||3,499|
|14.||Sony A7R III||..||+ +||90/100||4.5/5||5/5||Oct 2017||3,199|
|15.||Sony A9||5/5||+ +||89/100||5/5||5/5||Apr 2017||4,499|
|16.||Sony A7R II||5/5||+ +||90/100||5/5||5/5||Jun 2015||3,199|
|17.||Sony A7S II||5/5||+||..||4.5/5||5/5||Sep 2015||2,999|
|Notes: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.|
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. A score, therefore, has to be seen in close connection to the price and market introduction time of the camera, and rating-comparisons among cameras that span long time periods or concern very differently equipped models make little sense. 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: Pentax 645Z vs Sony A7R IV
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||Pentax 645Z||Sony A7R IV|
|Camera Type||Digital single lens reflex||Mirrorless system camera|
|Camera Lens||Pentax 645 mount lenses||Sony E mount lenses|
|Launch Date||April 2014||July 2019|
|Launch Price||USD 8,499||USD 3,499|
|Sensor Specs||Pentax 645Z||Sony A7R IV|
|Sensor Format||Medium Format Sensor||Full Frame Sensor|
|Sensor Size||43.8 x 32.8 mm||35.7 x 23.8 mm|
|Sensor Area||1436.64 mm2||849.66 mm2|
|Sensor Diagonal||54.7 mm||42.9 mm|
|Sensor Resolution||51.1 Megapixels||60.2 Megapixels|
|Image Resolution||8256 x 6192 pixels||9504 x 6336 pixels|
|Pixel Pitch||5.30 μm||3.76 μm|
|Pixel Density||3.56 MP/cm2||7.09 MP/cm2|
|Moiré control||no AA filter||no AA filter|
|Movie Capability||1080/60i Video||4K/30p Video|
|ISO Setting||100 - 204,800 ISO||100 - 32,000 ISO|
|ISO Boost||no Enhancement||50 - 102,400 ISO|
|Image Processor||PRIME III||BIONZ X|
|DXO Sensor Quality (score)||101||99|
|DXO Color Depth (bits)||26.0||26.0|
|DXO Dynamic Range (EV)||14.7||14.8|
|DXO Low Light (ISO)||4505||3344|
|Screen Specs||Pentax 645Z||Sony A7R IV|
|Viewfinder Type||Optical viewfinder||Electronic viewfinder|
|Viewfinder Field of View||98%||100%|
|Viewfinder Resolution||5760k dots|
|Top-Level Screen||Control Panel||no Top Display|
|LCD Framing||Live View||Live View|
|Rear LCD Size||3.2inch||3.0inch|
|LCD Resolution||1037k dots||1440k dots|
|LCD Attachment||Tilting screen||Tilting screen|
|Touch Input||no Touchscreen||Touchscreen|
|Shooting Specs||Pentax 645Z||Sony A7R IV|
|Focus System||Phase-detect AF||On-Sensor Phase-detect|
|Manual Focusing Aid||Focus Peaking||Focus Peaking|
|Max Shutter Speed (mechanical)||1/4000s||1/8000s|
|Continuous Shooting||3 shutter flaps/s||10 shutter flaps/s|
|Electronic Shutter||no E-Shutter||YES|
|Time-Lapse Photography||Intervalometer built-in||Intervalometer built-in|
|Image Stabilization||Lens stabilization only||In-body stabilization|
|Fill Flash||no On-Board Flash||no On-Board Flash|
|Storage Medium||SDXC cards||SDXC cards|
|Second Storage Option||Dual card slots||Dual card slots|
|UHS card support||UHS-I||Dual UHS-II|
|Connectivity Specs||Pentax 645Z||Sony A7R IV|
|Studio Flash||PC Sync socket||PC Sync socket|
|USB Connector||USB 3.0||USB 3.1|
|HDMI Port||mini HDMI||micro HDMI|
|Microphone Port||External MIC port||External MIC port|
|Headphone Socket||no Headphone port||Headphone port|
|Wifi Support||no Wifi||Wifi built-in|
|Near-Field Communication||no NFC||NFC built-in|
|Bluetooth Support||no Bluetooth||Bluetooth built-in|
|Body Specs||Pentax 645Z||Sony A7R IV|
|Environmental Sealing||Weathersealed body||Weathersealed body|
|Battery Life (CIPA)||650 shots per charge||670 shots per charge|
|In-Camera Charging||no USB charging||USB charging|
156 x 117 x 123 mm
(6.1 x 4.6 x 4.8 in)
129 x 96 x 78 mm
(5.1 x 3.8 x 3.1 in)
|Camera Weight||1550 g (54.7 oz)||665 g (23.5 oz)|
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