Pentax 645D vs K-3 III
The Pentax 645D and the Pentax K-3 III are two digital cameras that were officially introduced, respectively, in March 2010 and March 2021. Both are DSLR (Digital Single Lens Reflex) cameras that are based on a medium format (645D) and an APS-C (K-3 III) sensor. The 645D has a resolution of 39.5 megapixels, whereas the K-3 III provides 25.6 MP.
Below is an overview of the main specs of the two cameras as a starting point for the comparison.

Check 645D offers at
ebay.com

Check K-3 III price at
amazon.com
Going beyond this snapshot of core features and characteristics, what are the differences between the Pentax 645D and the Pentax K-3 III? 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.
Body comparison
An illustration of the physical size and weight of the Pentax 645D and the Pentax K-3 III is provided in the side-by-side display below. The two cameras are presented according to their relative size. 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.
The K-3 III can be obtained in two different colors (black, silver), while the 645D is only available in black.



If the front view area (width x height) of the cameras is taken as an aggregate measure of their size, the Pentax K-3 III is notably smaller (23 percent) than the Pentax 645D. Moreover, the K-3 III is substantially lighter (45 percent) than the 645D. 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.
The following table provides a synthesis of the main physical specifications of the two cameras and other similar ones. If you would like to visualize and compare a different camera combination, you can navigate to the CAM-parator app and make your selection from a broad list of cameras there.

| Camera Model |
Camera Width |
Camera Height |
Camera Depth |
Camera Weight |
Battery Life |
Weather Sealing |
Camera Launch |
Launch Price |
Street Price |
||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1. | Pentax 645D | 156 mm | 117 mm | 119 mm | 1480 g | 800 | Y | Mar 2010 | US$ 9 995 | ebay.com | |
| 2. | Pentax K-3 III | 135 mm | 104 mm | 74 mm | 820 g | 800 | Y | Mar 2021 | US$ 1 999 | amazon.com | |
| 3. | Canon 1D Mark IV | 156 mm | 157 mm | 80 mm | 1230 g | 1500 | Y | Oct 2009 | US$ 4 999 | ebay.com | |
| 4. | Canon 1D X | 158 mm | 168 mm | 83 mm | 1551 g | 1120 | Y | Oct 2011 | US$ 6 799 | ebay.com | |
| 5. | Canon 1D X Mark II | 158 mm | 168 mm | 83 mm | 1530 g | 1210 | Y | Feb 2016 | US$ 5 999 | ebay.com | |
| 6. | Fujifilm X-H1 | 140 mm | 97 mm | 86 mm | 673 g | 310 | Y | Feb 2018 | US$ 1 899 | ebay.com | |
| 7. | Leica S Typ 006 | 160 mm | 120 mm | 80 mm | 1260 g | .. | Y | Sep 2012 | US$ 21 949 | ebay.com | |
| 8. | Nikon D3S | 160 mm | 157 mm | 88 mm | 1240 g | 4200 | Y | Oct 2009 | US$ 5 199 | ebay.com | |
| 9. | Nikon D5 | 160 mm | 159 mm | 92 mm | 1415 g | 3780 | Y | Jan 2016 | US$ 6 499 | ebay.com | |
| 10. | Nikon D810 | 146 mm | 123 mm | 82 mm | 980 g | 1200 | Y | Jun 2014 | US$ 3 299 | ebay.com | |
| 11. | Nikon D850 | 146 mm | 124 mm | 79 mm | 1005 g | 1840 | Y | Jul 2017 | US$ 3 299 | amazon.com | |
| 12. | Pentax 645Z | 156 mm | 117 mm | 123 mm | 1550 g | 650 | Y | Apr 2014 | US$ 8 499 | ebay.com | |
| 13. | Pentax K-3 | 131 mm | 100 mm | 77 mm | 800 g | 560 | Y | Oct 2013 | US$ 1 299 | ebay.com | |
| 14. | Pentax K-3 II | 131 mm | 100 mm | 77 mm | 800 g | 720 | Y | Apr 2015 | US$ 1 099 | ebay.com | |
| 15. | Pentax K-70 | 126 mm | 93 mm | 74 mm | 688 g | 410 | Y | Jun 2016 | US$ 649 | ebay.com | |
| 16. | Pentax KP | 132 mm | 101 mm | 76 mm | 703 g | 390 | Y | Jan 2017 | US$ 1 099 | ebay.com | |
| 17. | Sony A7R | 127 mm | 94 mm | 48 mm | 465 g | 340 | Y | Oct 2013 | US$ 2 299 | ebay.com | |
| Note: Measurements and pricing do not include easily detachable parts, such as add-on or interchangeable lenses or optional viewfinders. | |||||||||||
Any camera decision will obviously take relative prices into account. 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 K-3 III was launched at a markedly lower price (by 80 percent) than the 645D, which puts it into a different market segment. Normally, street prices remain initially close to the MSRP, but after a couple of months, the first discounts appear. 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.
Sensor comparison
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 are more costly to manufacture and tend to lead to bigger and heavier cameras and lenses.
Of the two cameras under consideration, the Pentax 645D features a medium format sensor and the Pentax K-3 III an APS-C sensor. The sensor area in the K-3 III is 75 percent smaller. As a result of these sensor size differences, the cameras have a format factor of, respectively, 0.79 and 1.5. The sensor in the 645D has a native 4:3 aspect ratio, while the one in the K-3 III offers a 3:2 aspect.
Technology-wise, the K-3 III uses a more advanced image processing engine (PRIME V) than the 645D (PRIME II), with benefits for noise reduction, color accuracy, and processing speed.

With 39.5MP, the 645D offers a higher resolution than the K-3 III (25.6MP), but the 645D nevertheless has larger individual pixels (pixel pitch of 6.06μm versus 3.76μm for the K-3 III) due to its larger sensor. However, the K-3 III is a much more recent model (by 11 years) than the 645D, and its sensor will have benefitted from technological advances during this time that further 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.
The resolution advantage of the Pentax 645D implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the 645D for good quality output (200 dots per inch) amounts to 36.3 x 27.2 inches or 92.3 x 69.1 cm, for very good quality (250 dpi) 29.1 x 21.8 inches or 73.8 x 55.3 cm, and for excellent quality (300 dpi) 24.2 x 18.1 inches or 61.5 x 46.1 cm. The corresponding values for the Pentax K-3 III are 31 x 20.6 inches or 78.6 x 52.4 cm for good quality, 24.8 x 16.5 inches or 62.9 x 41.9 cm for very good quality, and 20.6 x 13.8 inches or 52.4 x 35 cm for excellent quality prints.
Unlike the 645D, the K-3 III has the capacity to capture high quality composite images (YESMP) 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 645D has a native sensitivity range from ISO 100 to ISO 1600. The corresponding ISO settings for the Pentax K-3 III are ISO 100 to ISO 160000 (no boost).
In terms of underlying technology, the 645D is build around a CCD sensor, while the K-3 III uses a CMOS imager. Both cameras use a Bayer filter for capturing RGB colors on a square grid of photosensors. This arrangement is found in most digital cameras.

For many cameras, data on sensor performance has been reported by DXO Mark. 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 adjacent table reports on the physical sensor characteristics and the outcomes of the DXO sensor quality tests for a sample of comparator-cameras.

| Camera Model |
Sensor Class |
Resolution (MP) |
Horiz. Pixels |
Vert. Pixels |
Video Format |
DXO Portrait |
DXO Landscape |
DXO Sports |
DXO Overall |
||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1. | Pentax 645D | Medium Format | 39.5 | 7264 | 5440 | none | 24.6 | 12.6 | 1262 | 82 | |
| 2. | Pentax K-3 III | APS-C | 25.6 | 6192 | 4128 | 4K/30p | 24.2 | 13.7 | 2083 | 85 | |
| 3. | Canon 1D Mark IV | APS-H | 16.0 | 4896 | 3264 | 1080/30p | 22.8 | 12.0 | 1320 | 74 | |
| 4. | Canon 1D X | Full Frame | 17.9 | 5184 | 3456 | 1080/30p | 23.8 | 11.8 | 2786 | 82 | |
| 5. | Canon 1D X Mark II | Full Frame | 20.0 | 5472 | 3648 | 4K/60p | 24.1 | 13.5 | 3207 | 88 | |
| 6. | Fujifilm X-H1 | APS-C | 24.0 | 6000 | 4000 | 4K/30p | 24.0 | 13.3 | 1806 | 82 | |
| 7. | Leica S Typ 006 | Medium Format | 37.5 | 7500 | 5000 | none | 23.9 | 12.2 | 824 | 76 | |
| 8. | Nikon D3S | Full Frame | 12.1 | 4256 | 2832 | 720/24p | 23.5 | 12.0 | 3253 | 82 | |
| 9. | Nikon D5 | Full Frame | 20.7 | 5588 | 3712 | 4K/30p | 25.1 | 12.3 | 2343 | 88 | |
| 10. | Nikon D810 | Full Frame | 36.2 | 7360 | 4912 | 1080/60p | 25.7 | 14.8 | 2853 | 97 | |
| 11. | Nikon D850 | Full Frame | 45.4 | 8256 | 5504 | 4K/30p | 26.4 | 14.8 | 2660 | 100 | |
| 12. | Pentax 645Z | Medium Format | 51.1 | 8256 | 6192 | 1080/60i | 26.0 | 14.7 | 4505 | 101 | |
| 13. | Pentax K-3 | APS-C | 24.1 | 6016 | 4000 | 1080/60i | 23.7 | 13.4 | 1216 | 80 | |
| 14. | Pentax K-3 II | APS-C | 24.1 | 6016 | 4000 | 1080/60i | 23.6 | 13.6 | 1106 | 80 | |
| 15. | Pentax K-70 | APS-C | 24.0 | 6000 | 4000 | 1080/60i | 23.8 | 13.1 | 1639 | 80 | |
| 16. | Pentax KP | APS-C | 24.1 | 6016 | 4000 | 1080/60i | 23.9 | 13.2 | 1699 | 81 | |
| 17. | Sony A7R | Full Frame | 36.2 | 7360 | 4912 | 1080/60p | 25.6 | 14.1 | 2746 | 95 | |
| Note: DXO values in italics represent estimates based on sensor size and age. | |||||||||||
Many modern cameras are not only capable of taking still images, but can also record movies. The K-3 III indeed provides for movie recording, while the 645D does not. The highest resolution format that the K-3 III can use is 4K/30p.
Feature comparison
Apart from body and sensor, cameras can and do differ across a range of features. The 645D and the K-3 III are similar in the sense that both have an optical viewfinder. The latter is useful for getting a clear image for framing even in brightly lit environments. The viewfinder in the K-3 III offers a wider field of view (100%) than the one in the 645D (98%), so that a larger proportion of the captured image is visible in the finder. On the other hand, the viewfinder of the 645D has a higher magnification (0.78x vs 0.70x), so that the size of the image transmitted appears closer to the size seen with the naked human eye. The following table reports on some other key feature differences and similarities of the Pentax 645D, the Pentax K-3 III, and comparable cameras.

| Camera Model |
Viewfinder (Type or 000 dots) |
Control Panel (yes/no) |
LCD Specifications (inch/000 dots) |
LCD Attach- ment |
Touch Screen (yes/no) |
Max Shutter Speed * |
Max Shutter Flaps * |
Built-in Flash (yes/no) |
Built-in Image Stab |
||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1. | Pentax 645D | optical | Y | 3.0 / 921 | fixed | n | 1/4000s | 1.1/s | n | n | |
| 2. | Pentax K-3 III | optical | Y | 3.2 / 1620 | fixed | Y | 1/8000s | 12.0/s | n | Y | |
| 3. | Canon 1D Mark IV | optical | Y | 3.0 / 920 | fixed | n | 1/8000s | 10.0/s | n | n | |
| 4. | Canon 1D X | optical | Y | 3.2 / 1040 | fixed | n | 1/8000s | 14.0/s | n | n | |
| 5. | Canon 1D X Mark II | optical | Y | 3.2 / 1620 | fixed | Y | 1/8000s | 16.0/s | n | n | |
| 6. | Fujifilm X-H1 | 3690 | Y | 3.0 / 1040 | full-flex | Y | 1/8000s | 14.0/s | n | Y | |
| 7. | Leica S Typ 006 | optical | Y | 3.0 / 922 | fixed | n | 1/4000s | 1.5/s | n | n | |
| 8. | Nikon D3S | optical | Y | 3.0 / 921 | fixed | n | 1/8000s | 11.0/s | n | n | |
| 9. | Nikon D5 | optical | Y | 3.2 / 2359 | fixed | Y | 1/8000s | 14.0/s | n | n | |
| 10. | Nikon D810 | optical | Y | 3.2 / 1229 | fixed | n | 1/8000s | 5.0/s | Y | n | |
| 11. | Nikon D850 | optical | Y | 3.2 / 2359 | tilting | Y | 1/8000s | 9.0/s | n | n | |
| 12. | Pentax 645Z | optical | Y | 3.2 / 1037 | tilting | n | 1/4000s | 3.0/s | n | n | |
| 13. | Pentax K-3 | optical | Y | 3.2 / 1037 | fixed | n | 1/8000s | 8.3/s | Y | Y | |
| 14. | Pentax K-3 II | optical | Y | 3.2 / 1037 | fixed | n | 1/8000s | 8.3/s | n | Y | |
| 15. | Pentax K-70 | optical | n | 3.0 / 921 | swivel | n | 1/6000s | 6.0/s | Y | Y | |
| 16. | Pentax KP | optical | n | 3.0 / 921 | tilting | n | 1/6000s | 7.0/s | Y | Y | |
| 17. | Sony A7R | 2400 | n | 3.0 / 1230 | tilting | n | 1/8000s | 4.0/s | n | n | |
| Note: *) Information refers to the mechanical shutter, unless the camera only has an electronic one. | |||||||||||
One differentiating feature between the two cameras concerns the touch sensitivity of the rear screen. The K-3 III has a touchscreen, while the 645D has a conventional panel. Touch control can be particularly helpful, for example, for setting the focus point.
The Pentax 645D and the Pentax K-3 III 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 645D and the K-3 III write their files to SDXC cards. Both cameras feature dual card slots, which can be very useful in case a memory card fails. The K-3 III supports UHS-II cards on its first slot and UHS-I on its second one, while the 645D cannot take advantage of Ultra High Speed SD cards.
Connectivity comparison
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 645D and Pentax K-3 III and, in particular, the interfaces the cameras (and selected comparators) provide for accessory control and data transfer.

| Camera Model |
Hotshoe Port |
Internal Mic / Speaker |
Microphone Port |
Headphone Port |
HDMI Port |
USB Port |
WiFi Support |
NFC Support |
Bluetooth Support |
||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1. | Pentax 645D | Y | stereo / - | - | - | - | 2.0 | - | - | - | |
| 2. | Pentax K-3 III | Y | stereo / mono | Y | Y | micro | 3.2 | Y | - | Y | |
| 3. | Canon 1D Mark IV | Y | stereo / - | Y | - | mini | 2.0 | - | - | - | |
| 4. | Canon 1D X | Y | mono / - | Y | - | mini | 2.0 | - | - | - | |
| 5. | Canon 1D X Mark II | Y | mono / mono | Y | Y | mini | 3.0 | - | - | - | |
| 6. | Fujifilm X-H1 | Y | stereo / mono | Y | - | micro | 3.0 | Y | - | - | |
| 7. | Leica S Typ 006 | Y | - / - | - | - | mini | 2.0 | - | - | - | |
| 8. | Nikon D3S | Y | stereo / - | - | - | mini | 2.0 | - | - | - | |
| 9. | Nikon D5 | Y | stereo / mono | Y | Y | mini | 3.0 | - | - | - | |
| 10. | Nikon D810 | Y | stereo / mono | Y | Y | mini | 3.0 | Y | - | - | |
| 11. | Nikon D850 | Y | stereo / mono | Y | Y | mini | 3.0 | Y | Y | Y | |
| 12. | Pentax 645Z | Y | stereo / mono | Y | - | mini | 3.0 | - | - | - | |
| 13. | Pentax K-3 | Y | mono / mono | Y | Y | mini | 3.0 | - | - | - | |
| 14. | Pentax K-3 II | Y | mono / mono | Y | Y | mini | 3.0 | - | - | - | |
| 15. | Pentax K-70 | Y | stereo / mono | Y | - | mini | 2.0 | Y | - | - | |
| 16. | Pentax KP | Y | stereo / mono | Y | - | - | 2.0 | Y | - | - | |
| 17. | Sony A7R | Y | stereo / mono | Y | Y | micro | 2.0 | Y | Y | - |
It is notable that the K-3 III offers wifi support, which can be a very convenient means to transfer image data to an off-camera location. In contrast, the 645D does not provide wifi capability.
Both cameras feature a PC Sync terminal to control professional strobe lights, which will be appreciated by studio photographers.
Travel and landscape photographers will find it useful that the K-3 III has an internal geolocalization sensor and can record GPS coordinates in its EXIF data.
The K-3 III is a recent model that features in the current product line-up of Pentax. In contrast, the 645D has been discontinued (but can be found pre-owned on ebay). As a replacement in the same line of cameras, the 645D was succeeded by the Pentax 645Z. Further information on the features and operation of the 645D and K-3 III can be found, respectively, in the Pentax 645D Manual (free pdf) or the online Pentax K-3 III Manual.
Review summary
So what conclusions can be drawn? Is there a clear favorite between the Pentax 645D and the Pentax K-3 III? Which camera is better? The listing below highlights the relative strengths of the two models.
Arguments in favor of the Pentax 645D:
- More detail: Offers more megapixels (39.5 vs 25.6MP) with a 22% higher linear resolution.
- Larger viewfinder image: Features a viewfinder with a higher magnification (0.78x vs 0.70x).
- More heavily discounted: Has been available for much longer (launched in March 2010).
Reasons to prefer the Pentax K-3 III:
- High quality composites: Can combine several shots after pixel-shifting its sensor.
- Better jpgs: Has a more modern image processing engine (PRIME V vs PRIME II).
- Broader imaging potential: Can capture not only stills but also 4K/30p video.
- More complete view: Has a viewfinder with a larger field of view (100% vs 98%).
- Larger screen: Has a bigger rear LCD (3.2" vs 3.0") for image review and settings control.
- More detailed LCD: Has a higher resolution rear screen (1620k vs 921k 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 (12 vs 1.1 flaps/sec) to capture the decisive moment.
- More compact: Is smaller (135x104mm vs 156x117mm) and will fit more readily into a bag.
- Less heavy: Has a lower weight (by 660g or 45 percent) and is thus easier to take along.
- Sharper images: Has stabilization technology built-in to reduce the impact of hand-shake.
- Easier geotagging: Features an internal GPS sensor to log localization data.
- Faster data transfer: Supports a more advanced USB protocol (3.2 vs 2.0).
- Easier file upload: Has wifi built in for automatic backup or image transfer to the web.
- Easier wireless transfer: Supports Bluetooth for image sharing without cables.
- Faster buffer clearing: Supports Ultra High Speed (UHS-II and UHS-I) SDXC cards.
- More affordable: Was introduced into a lower priced category (80 percent cheaper at launch).
- More modern: Reflects 11 years of technical progress since the 645D launch.
If the count of relative strengths (bullet points above) is taken as a measure, the K-3 III is the clear winner of the contest (19 : 3 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 before making a camera decision. A professional wedding photographer will view the differences between cameras in a way that diverges from the perspective of a travel photog, and a person interested in cityscapes has distinct needs from a macro 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 645D and the Pentax K-3 III place the cameras among the top in their class? Find out in the latest Best DSLR Camera listing 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 645D and the K-3 III 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.
Expert reviews
This is why hands-on reviews by experts are important. The adjacent summary-table relays the overall verdicts of several of the most popular camera review sites (amateurphotographer [AP], cameralabs [CL], digitalcameraworld [DCW], 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.

| Camera Model |
AP score |
CL score |
DCW score |
DPR score |
EPZ score |
PB score |
Camera Launch |
Launch Price |
Street Price |
||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1. | Pentax 645D | 5/5 | .. | .. | .. | .. | .. | Mar 2010 | US$ 9 995 | ebay.com | |
| 2. | Pentax K-3 III | 4/5 | .. | 3/5 | .. | 4.5/5 | .. | Mar 2021 | US$ 1 999 | amazon.com | |
| 3. | Canon 1D Mark IV | 5/5 | .. | .. | 89/100 | .. | .. | Oct 2009 | US$ 4 999 | ebay.com | |
| 4. | Canon 1D X | 5/5 | .. | .. | .. | 4.5/5 | 4.5/5 | Oct 2011 | US$ 6 799 | ebay.com | |
| 5. | Canon 1D X Mark II | .. | .. | 4.5/5 | 89/100 | 4.5/5 | 4.5/5 | Feb 2016 | US$ 5 999 | ebay.com | |
| 6. | Fujifilm X-H1 | .. | + | 5/5 | 86/100 | 4.5/5 | 4.5/5 | Feb 2018 | US$ 1 899 | ebay.com | |
| 7. | Leica S Typ 006 | .. | .. | .. | .. | .. | .. | Sep 2012 | US$ 21 949 | ebay.com | |
| 8. | Nikon D3S | 5/5 | .. | .. | 89/100 | 4.5/5 | 5/5 | Oct 2009 | US$ 5 199 | ebay.com | |
| 9. | Nikon D5 | .. | .. | 4/5 | 89/100 | 4.5/5 | 5/5 | Jan 2016 | US$ 6 499 | ebay.com | |
| 10. | Nikon D810 | 5/5 | .. | 5/5 | 86/100 | 5/5 | 4.5/5 | Jun 2014 | US$ 3 299 | ebay.com | |
| 11. | Nikon D850 | 4.5/5 | + + | 5/5 | 89/100 | 4.5/5 | 5/5 | Jul 2017 | US$ 3 299 | amazon.com | |
| 12. | Pentax 645Z | 5/5 | .. | 3.5/5 | .. | 4.5/5 | 5/5 | Apr 2014 | US$ 8 499 | ebay.com | |
| 13. | Pentax K-3 | 4/5 | .. | .. | 83/100 | 5/5 | 5/5 | Oct 2013 | US$ 1 299 | ebay.com | |
| 14. | Pentax K-3 II | 4.5/5 | .. | .. | .. | 5/5 | 5/5 | Apr 2015 | US$ 1 099 | ebay.com | |
| 15. | Pentax K-70 | 4.5/5 | .. | 4/5 | 79/100 | 4.5/5 | 4.5/5 | Jun 2016 | US$ 649 | ebay.com | |
| 16. | Pentax KP | 4/5 | .. | 3/5 | 82/100 | 5/5 | 4.5/5 | Jan 2017 | US$ 1 099 | ebay.com | |
| 17. | Sony A7R | 5/5 | + + | .. | 82/100 | 4.5/5 | 5/5 | Oct 2013 | US$ 2 299 | ebay.com | |
| Note: (+ +) 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, kindly note that some of the listed sites have over time developped their review approaches and their reporting style.

Check 645D offers at
ebay.com

Check K-3 III price at
amazon.com
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 use the search menu below. As an alternative, you can also directly jump to any one of the listed comparisons that were previously generated by the CAM-parator tool.
- Canon 100D vs Pentax K-3 III
- Canon G1 X vs Pentax 645D
- Canon M50 Mark II vs Pentax K-3 III
- Canon SX520 vs Pentax 645D
- Nikon D7500 vs Pentax 645D
- Nikon P900 vs Pentax 645D
- Nikon Z6 II vs Pentax K-3 III
- OM System OM-3 vs Pentax K-3 III
- Olympus E-P5 vs Pentax 645D
- Panasonic L10 vs Pentax K-3 III
- Panasonic S9 vs Pentax K-3 III
- Panasonic TS7 vs Pentax 645D
Specifications: Pentax 645D vs Pentax K-3 III
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 645D | Pentax K-3 III |
|---|---|---|
| Camera Type | Digital single lens reflex | Digital single lens reflex |
| Camera Lens | Pentax 645 mount lenses | Pentax K mount lenses |
| Launch Date | March 2010 | March 2021 |
| Launch Price | USD 9,995 | USD 1,999 |
| Sensor Specs | Pentax 645D | Pentax K-3 III |
| Sensor Technology | CCD | CMOS |
| Sensor Format | Medium Format Sensor | APS-C Sensor |
| Sensor Size | 44.0 x 33.0 mm | 23.3 x 15.5 mm |
| Sensor Area | 1452 mm2 | 361.15 mm2 |
| Sensor Diagonal | 55 mm | 28 mm |
| Crop Factor | 0.79x | 1.5x |
| Sensor Resolution | 39.5 Megapixels | 25.6 Megapixels |
| Image Resolution | 7264 x 5440 pixels | 6192 x 4128 pixels |
| Pixel Pitch | 6.06 μm | 3.76 μm |
| Pixel Density | 2.72 MP/cm2 | 7.08 MP/cm2 |
| Moiré control | no AA filter | no AA filter |
| Movie Capability | no Video | 4K/30p Video |
| ISO Setting | 100 - 1,600 ISO | 100 - 160,000 ISO |
| Image Processor | PRIME II | PRIME V |
| DXO Sensor Quality (score) | 82 | .. |
| DXO Color Depth (bits) | 24.6 | .. |
| DXO Dynamic Range (EV) | 12.6 | .. |
| DXO Low Light (ISO) | 1262 | .. |
| Screen Specs | Pentax 645D | Pentax K-3 III |
| Viewfinder Type | Optical viewfinder | Optical viewfinder |
| Viewfinder Field of View | 98% | 100% |
| Viewfinder Magnification | 0.78x | 0.70x |
| Top-Level Screen | Control Panel | Control Panel |
| LCD Framing | Live View | |
| Rear LCD Size | 3.0inch | 3.2inch |
| LCD Resolution | 921k dots | 1620k dots |
| LCD Attachment | Fixed screen | Fixed screen |
| Touch Input | no Touchscreen | Touchscreen |
| Shooting Specs | Pentax 645D | Pentax K-3 III |
| Focus System | Phase-detect AF | Phase-detect AF |
| Manual Focusing Aid | no Peaking Feature | Focus Peaking |
| Max Shutter Speed (mechanical) | 1/4000s | 1/8000s |
| Continuous Shooting | 1.1 shutter flaps/s | 12 shutter flaps/s |
| Shutter Life Expectancy | 50 000 actuations | 200 000 actuations |
| 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 |
| Single or Dual Card Slots | Dual card slots | Dual card slots |
| UHS card support | no | Single UHS-II |
| Connectivity Specs | Pentax 645D | Pentax K-3 III |
| External Flash | Hotshoe | Hotshoe |
| Studio Flash | PC Sync socket | PC Sync socket |
| USB Connector | USB 2.0 | USB 3.2 |
| HDMI Port | no HDMI | micro HDMI |
| Microphone Port | no MIC socket | External MIC port |
| Headphone Socket | no Headphone port | Headphone port |
| Wifi Support | no Wifi | Wifi built-in |
| Bluetooth Support | no Bluetooth | Bluetooth built-in |
| Geotagging | no internal GPS | GPS built-in |
| Body Specs | Pentax 645D | Pentax K-3 III |
| Environmental Sealing | Weathersealed body | Weathersealed body |
| Battery Type | Pentax D-LI90 | Pentax D-LI90 |
| Battery Life (CIPA) | 800 shots per charge | 800 shots per charge |
| Body Dimensions |
156 x 117 x 119 mm (6.1 x 4.6 x 4.7 in) |
135 x 104 x 74 mm (5.3 x 4.1 x 2.9 in) |
| Camera Weight | 1480 g (52.2 oz) | 820 g (28.9 oz) |

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