Overview
As a medium format camera the Pentax 645Z has a sensor that’s considerably bigger than the sensors in full frame cameras such as the Nikon D810 and Canon 5D Mark III. In fact, as it measures 43.8×32.8mm, it’s around 1.68x their size.
Unlike the Pentax 645D that the 645Z replaces, the new camera has a Sony CMOS sensor, which should be good news for noise control. What’s more, the pixel count has been boosted from 40 million to 51 million, so detail resolution should be very high. However, this has been boosted further by the fact that, like Hasselblad and Phase One medium format cameras with the same chip, there’s no anti-aliasing filter.
Pentax has also coupled the sensor with a PRIME III image engine, first seen in the Pentax K-3 APS-C format SLR. This enables up to 10 raw images (or 30 images large highest quality JPEGs) to be shot at a maximum speed of approximately three frames per second (fps).
There are a few other significant upgrades. The maximum sensitivity setting, for example, is now ISO 204,800, significantly higher than the ISO 6400 maximum offered by most other medium format cameras. There’s also a tilting 3.2-inch 1,037,000-dot LCD screen which is capable of showing a Live View image and Full HD (1920 x 1080 pixels) movies may be shot at 60i/30P in H.264 format.
In addition to the built-in stereo microphone, the 645Z has a stereo mic port and audio level control is possible.
Pentax has also given the 645Z the SAFOX 11 phase-detection autofocus (AF) system found in the K-3. This has 27 AF points, 25 of which are the more sensitive cross-type. It’s also capable of working down to -3EV.
Exposure can be controlled manually or automatically with information being provided by the Pentax Real-Time Scene Analysis System. This consists of an 86,000-pixel RGB light-metering sensor and an algorithm. Pentax claims this improves on exposure-control accuracy and it provides data to enhance autofocusing accuracy and white-balance adjustment.
There are also two SD/SDHC/SDXC card ports, with the second port compatible with Flu cards to allow wireless shutter release and image transfer and via a smartphone.
Build and handling
Pentax has used the same design and control layout for the 645Z as it did for the 645D, so those upgrading will find the transition pretty smooth. The body is covered fairly liberally with controls that give a quick route to key features such as sensitivity, white balance and exposure compensation.
However, there’s a limited number that can be customised to access alternative features, just the RAW button on the top-left of the camera and the (LCD) Illumination button. The RAW button is intended to allow users to switch quickly from shooting JPEG images to raw files, or from raw files to simultaneous raw and JPEG capture. I find it hard to imagine that many medium format camera users would want to move away from raw files in many situations. Fortunately, this button can be set to Optical Preview (depth of field preview) or Digital Preview. Digital Preview captures an image at the selected settings for examination on the camera’s screen, but it isn’t written to the card.
The Illumination button can be used to trigger a compatible flashgun to emit a modelling flash or a test flash. Meanwhile the AF button can be set to allow back-button focusing, where the AF function is removed from the shutter release and the Preview Dial around the shutter release can be used to access Optical or Digital Preview.
There are however, three User mode settings can be saved for access via the main mode dial. It’s also possible to save a new name for each User setting to help remind you of the key features. However, this name is only shown briefly on the main screen after turning to the option on the mode dial and it isn’t displayed on the information screen that appears when OK is pressed – the original name, User1, User2 or User3, is shown instead. I suspect this could be rectified by a firmware upgrade.
Like the 645D, the 645Z has seals that make it weather and dust resistant. It also has the same deep grip and, despite its larger size and relatively heavy weight (over 1.5Kg without a lens), it feels comfortable in the hand. It really is feasible to use this camera hand-held, and thanks to its impressive sensitivity range it is possible that this camera will be used so more than any other digital medium format camera.
I used the camera with a weather resistant lens mounted for about 30 minutes in persistent drizzle and didn’t encounter any problems. Despite the water on the grip and covering the buttons and dials it continued to function correctly, and I was able to keep a good grip on it.
At first glance it may seem that those with small hands may struggle to adjust some settings on the camera, but rather than needing to press a button while simultaneously scrolling a dial, most adjustments can be made either with a single press to select the desired option and then using a dial or repeated pressing of a button.
As the user interface is fairly similar to that of Pentax’s K-series cameras it’s very easy to get to grips with the 645Z, and even those who have never used a medium format camera before will soon feel comfortable using it. That said, the menu looks very dated.
Although there are 27 individually selectable AF points, they are all clustered quite close to the centre of the image frame, so the focus-and-recompose technique comes in handy on many occasions with off-centre subjects.
Being an SLR, the 645Z has a reflex mirror that lifts to allow an exposure to be made. Naturally this is quite a large unit and, while it’s not quite the door-slam of some medium format models, you are certainly aware of its movements. It’s helpful that it’s possible to set mirror lock-up mode directly via a switch on the side of the camera, as this is likely to be used for studio work.
The viewfinder is large and bright, but with 98% coverage it doesn’t quite display the whole image and you can expect to find the odd extra inclusion around the edges of the frame on occasion. The LCD screen is also clear and provides a detailed view, whether composing using Live View mode or reviewing images. The fact that the screen tilts is especially useful when composing images on a tripod in the studio or when out shooting landscapes.
It’s also helpful that the screen’s display can be set to rotate to make it easier to read when shooting in upright format.
While the screen provides a clear view indoors, it is much harder to see outside on the default settings. Pushing the brightness value to the maximum helps, but you’ll need to check the histogram to be sure that the image is correctly exposed.
Performance
The key advantage of having 51 million effective pixels on a medium format sensor is that it’s possible to record lots of detail. Also, because those pixels are relatively large, they generate a strong signal that means noise levels can be kept down. This is immediately apparent in the images from the 645Z – they have a huge amount of sharp detail and little noise at the low to mid-range sensitivity settings.
Even at the highest sensitivity setting (ISO 204,800) noise is controlled comparatively well. There is some coloured speckling visible, but detail appears to be better retained than in images from small format SLRs with such settings. Nevertheless, most photographers will still only want to use it for emergencies as there’s a visible granular texture and colour saturation drops significantly.
Stepping down to ISO 6400 results in images that look significantly better, with plenty of detail, making using this setting realistic. It makes the 645Z much more versatile than the ‘average’ digital medium format camera and it’s feasible that owners might use it handheld to shoot events.
The raw files, which are in the convenient DNG format or Pentax’s own PEF format, naturally have more detail than simultaneously captured JPEGs, and it’s possible to strike a nice balance between detail visibility and noise suppression during post-capture processing.
Thanks to the 645Z’s relative portability the auto white balance and general purpose metering systems are more likely to be used than with some more studio-bound medium format cameras. As we have found with other Pentax SLRs, the Multi-segment metering system (which in this case uses a dedicated 86K pixel RGB sensor) generally behaves well, but it is prone to underexposing when faced with bright subjects or if there are large bright areas in the scene. This is something that the target user of the camera is likely to anticipate and is easily dealt with via the exposure compensation control.
The automatic white balance system also does a good job in a range of natural lighting conditions, but as is often the case, a custom white balance setting is a better bet in artificial light. Given the level of photographic experience that the typical 645Z user is likely to have, many would automatically set a custom white balance anyway, or simply resolve to perfect white balance when processing the raw files.
Similarly, most users are likely to create any image effects themselves rather than use the Custom Image options (Bright, Natural, Portrait, Landscape, Vibrant, Radiant, Muted, Bleach bypass, Reversal film, Monochrome, Cross processing) that tailor the appearance of JPEGs, but they are a fun addition and something we are familiar with from small format SLRs and compact system cameras.
In the Natural setting, the 645Z generally delivers pleasant looking images with natural colours.
While the 645Z’s AF system can’t compete with a high-end small format SLRs, it is pretty impressive considering the size and weight of the elements inside the compatible lenses. It’s much faster than most SLRs’ Live View AF systems, and even in quite low light it homed in on its target decisively with no hunting, though it starts to struggle when subjects get close to the minimum distance. It’s a viable option for hand-held photography.
Image quality and resolution
As part of our image quality testing for the Pentax 645Z review, we’ve shot our resolution chart.
If you view our crops of the resolution chart’s central section at 100% (or Actual Pixels) you will see that, for example, at ISO 100 the Pentax 645Z is capable of resolving up to around 38 (line widths per picture height x100) in its highest quality JPEG files.
For a full explanation of what our resolution charts mean, and how to read them, check out our full explanation of our camera testing resolution charts.
Examining images of the chart taken at each sensitivity setting reveals the following resolution scores in line widths per picture height x100:
JPEG
Full ISO 100 image. See 100% crops below:
ISO 100. Score: 38. Click here to see full resolution image
ISO 200. Score: 38. Click here to see full resolution image
ISO 400. Score: 38. Click here to see full resolution image
ISO 800. Score: 38. Click here to see full resolution image
ISO 1600. Score: 36. Click here to see full resolution image
ISO 3200. Score: 36. Click here to see full resolution image
ISO 6400. Score: 36. Click here to see full resolution image
ISO 12800. Score: 34. Click here to see full resolution image
ISO 25600. Score: 32. Click here to see full resolution image
ISO 51200. Score: 28. Click here to see full resolution image
ISO 102400. Score: 24. Click here to see full resolution image
ISO 204800. Score: 18. Click here to see full resolution image
Raw
ISO 100. Score: 38. Click here to see full resolution image
ISO 200. Score: 38. Click here to see full resolution image
ISO 400. Score: 38. Click here to see full resolution image
ISO 800. Score: 38. Click here to see full resolution image
ISO 1600. Score: 38. Click here to see full resolution image
ISO 3200. Score: 36 Click here to see full resolution image
ISO 6400. Score: 34. Click here to see full resolution image
ISO 12800. Score: 32. Click here to see full resolution image
ISO 25600. Score: 28. Click here to see full resolution image
ISO 51200. Score: 24. Click here to see full resolution image
ISO 102400. Score: 20. Click here to see full resolution image
ISO 204800. Score: 16. Click here to see full resolution image
Noise and dynamic range
We shoot a specially designed chart in carefully controlled conditions and the resulting images are analysed using DXO Analyzer software to generate the data to produce the graphs below.
A high signal to noise ratio (SNR) indicates a cleaner and better quality image.
For more more details on how to interpret our test data, check out our full explanation of our noise and dynamic range tests.
Here we compare the Pentax 645Z to the Nikon D810, Canon 5D Mk III and Sony Alpha 7R.
JPEG signal to noise ratio
At the 645Z’s base ISO100 sensitivity, its 51.4MP sensor manages to produce cleaner images than the 36.3MP D810 and 36.4MP Alpha 7R. The 22.3MP 5D Mark III is the camera to beat though, providing the highest signal to noise ratio up to ISO1600. At ISO3200 Pentax takes the lead and the gap widens as sensor sensitivities increase, demonstrating the 645Z’s ability to generate clean images in low light.
Raw signal to noise ratio
Analysing the 645Z’s raw files (after conversion to TIFF) we see the same trend as shown in the JPEG results, with Pentax and Canon vying for top honours. At ISO100 the D810 and Alpha 7R are close rivals, but images become progressively noisier than those from the 645Z at higher sensitivities. This could be due in part to the 645Z’s sensor being comprised of larger (5.3-micron) photosites offering potentially higher light sensitivity than the 4.88-micron photosites on the D810 and Alpha 7R’s sensors.
JPEG dynamic range
All the cameras manage very high JPEG dynamic range scores and are evenly matched up to ISO1600. Here the D810 and Alpha 7R’s scores start to fall more sharply than the 645Z and 5D Mark III’s results, which in turn follow the same trend at ISO3200. At ISO6400 the 645Z starts to establish a clear lead and maintains it up to its maximum ISO204,800 sensitivity.
Raw dynamic range
Converting raw files to TIFF for analysis reveals more pronounced differences in dynamic range than JPEG images reveal. Here the 645Z is clearly superior to the full-frame competition throughout the sensitivity range, indicating that it’s capable of recording the widest range of tones.
Sensitivity and noise images
JPEG
Full ISO 100 image, see 100% crops below.
ISO 100. Click here for full resolution image
ISO 200. Click here for full resolution image
ISO 400. Click here for full resolution image
ISO 800. Click here for full resolution image
ISO 1600. Click here for full resolution image
ISO 3200. Click here for full resolution image
ISO 6400. Click here for full resolution image
ISO 12800. Click here for full resolution image
ISO 25600. Click here for full resolution image
ISO 51200. Click here for full resolution image
ISO 102400. Click here for full resolution image
ISO 204800. Click here for full resolution image
Raw
ISO 100. Click here for full resolution image
ISO 200. Click here for full resolution image
ISO 400. Click here for full resolution image
ISO 800. Click here for full resolution image
ISO 1600. Click here for full resolution image
ISO 3200. Click here for full resolution image
ISO 6400. Click here for full resolution image
ISO 12800. Click here for full resolution image
ISO 25600. Click here for full resolution image
ISO 51200. Click here for full resolution image
ISO 102400. Click here for full resolution image
ISO 204800. Click here for full resolution image
Sample images
Click here for full resolution image
Images are usually pleasantly natural straight from the camera at the default settings.
Click here for full resolution image
This bright scene required 1EV of positive exposure compensation to avoid underexposure.
Click here for full resolution image
This shot taken with the Pentax 120mm macro lens shows how restricted depth of field can be at f/16.
Click here for full resolution image
Here’s the f/22 version which has a slightly sharper background.
Click here for full resolution image
The detail in the stitching of these boots is very impressive.
Click here for full resolution image
Using the automatic white balance setting produced a slightly cool image in the dappled light here.
Click here for full resolution image
Using the daylight white balance setting produced a slightly warmer image.
Click here for full resolution image
It’s a little on the large side for street photography, but the 645Z is capable enough.
Click here for full resolution image
Noise is extremely well controlled at ISO 6400.
Click here for full resolution image
It’s pretty good at ISO 204,800 as well, but there’s a drop in colour saturation.
Click here for full resolution image
It’s useful to be able to shoot black and white JPEGs while recording full-colour raw files for conversion.
Click here for full resolution image
The metering system has coped well with this bright scene.
Click here for full resolution image
Another well exposed images with nice, vibrant colours.
Verdict
In the days of film photography, medium format cameras weren’t just the preserve of professional photographers, many enthusiasts used them as well. Just as with digital photography, the larger frame brought better quality images that could be blown up to bigger sizes.
Sadly, the price of the average digital medium format camera puts it well beyond the reach of most enthusiasts. At around £7,700/US$9,700/AU$12,700 for a camera body and 55mm lens the Pentax 645Z is still too expensive for most enthusiast photographers, but it costs just a fraction of what a comparable Hasselblad kit would set you back, so there is lots of interest amongst experienced photographers.
Despite being at the ‘more affordable’ end of the digital medium format camera market, the Pentax 645Z gives a very good account of itself. It’s a solidly built camera with weatherproof and dustproof seals that make it safe to use outside of the studio. It’s not the lightest camera in the world, but it has chunky, comfortable grips that make it pleasant to use hand-held. The white balance, autofocus and exposure systems also work well (although you need to look out for bright areas triggering underexposure) and its not far off being a ‘point-and-shot’ medium format camera if you want it to behave in such a way.
In addition, the average enthusiast photographer who knows his or her way around a mid-to-high-end SLR will find that they quickly get to grips with its control layout and menu arrangement.
The controls and menus are also responsive and there are some useful features such as the ability for the screen display to rotate when the camera is turned for upright images. Live View technology is novel on a medium format camera and its seems a very logical addition. Medium format cameras are often used mounted on a tripod and in the studio, both of which make using Live View viable. It’s a shame that Pentax has opted to give the 645Z a tilting screen rather than a full articulating one, which would make using Live View even more convenient.
We liked
The step up to medium photography can be daunting, but Pentax has made it much easier by using a similar interface for the 645Z as it does for its K-series SLRs. It doesn’t take long to feel confident using the camera and the large grip, fast autofocusing system and conveniently laid out controls make it easy to use hand-held.
I also really liked being able to compose images on the rear screen when the camera was in the studio, it seems a natural progression from a waist-level finder on a medium format camera.
We disliked
It’s great to have quick access to features such as mirror lock-up, which has a dedicated switch, but there are a few controls on the top of the camera that are likely to be superfluous for many 645Z users and it’s a shame that there aren’t more customisation options available for users to set-up the camera to meet their own specific requirements.
The menu also looks very dated.
Final verdict
The main aim of using a medium format camera is to produce higher quality images than is possible with a small format camera and the Pentax 645Z certainly delivers in this respect. Images have a superb amount of detail and colours are generally natural, yet vibrant straight from the camera. As mentioned earlier, you need to keep an eye on the exposure when there are bright areas in the scene, but that well within the capability of the type of photographer who will be attracted to the 645Z.
Another benefit of having such a large sensor is that it’s possible to restrict depth of field dramatically. This is immediately apparent as soon as you start shooting with the 645Z and many photographers will find that they need to use smaller apertures than they are used to in order to produce a wide enough sharp area.
It will be very interesting to see how the 645Z sells, especially now that we have tiny full-frame compact system cameras like the Sony Alpha 7R and versatile high-resolution SLRs like the Nikon D810.
Powered by WPeMatico
Overview
As a medium format camera the Pentax 645Z has a sensor that’s considerably bigger than the sensors in full frame cameras such as the Nikon D810 and Canon 5D Mark III. In fact, as it measures 43.8×32.8mm, it’s around 1.68x their size.
Unlike the Pentax 645D that the 645Z replaces, the new camera has a Sony CMOS sensor, which should be good news for noise control. What’s more, the pixel count has been boosted from 40 million to 51 million, so detail resolution should be very high. However, this has been boosted further by the fact that, like Hasselblad and Phase One medium format cameras with the same chip, there’s no anti-aliasing filter.
Pentax has also coupled the sensor with a PRIME III image engine, first seen in the Pentax K-3 APS-C format SLR. This enables up to 10 raw images (or 30 images large highest quality JPEGs) to be shot at a maximum speed of approximately three frames per second (fps).
There are a few other significant upgrades. The maximum sensitivity setting, for example, is now ISO 204,800, significantly higher than the ISO 6400 maximum offered by most other medium format cameras. There’s also a tilting 3.2-inch 1,037,000-dot LCD screen which is capable of showing a Live View image and Full HD (1920 x 1080 pixels) movies may be shot at 60i/30P in H.264 format.
In addition to the built-in stereo microphone, the 645Z has a stereo mic port and audio level control is possible.
Pentax has also given the 645Z the SAFOX 11 phase-detection autofocus (AF) system found in the K-3. This has 27 AF points, 25 of which are the more sensitive cross-type. It’s also capable of working down to -3EV.
Exposure can be controlled manually or automatically with information being provided by the Pentax Real-Time Scene Analysis System. This consists of an 86,000-pixel RGB light-metering sensor and an algorithm. Pentax claims this improves on exposure-control accuracy and it provides data to enhance autofocusing accuracy and white-balance adjustment.
There are also two SD/SDHC/SDXC card ports, with the second port compatible with Flu cards to allow wireless shutter release and image transfer and via a smartphone.
Build and handling
Pentax has used the same design and control layout for the 645Z as it did for the 645D, so those upgrading will find the transition pretty smooth. The body is covered fairly liberally with controls that give a quick route to key features such as sensitivity, white balance and exposure compensation.
However, there’s a limited number that can be customised to access alternative features, just the RAW button on the top-left of the camera and the (LCD) Illumination button. The RAW button is intended to allow users to switch quickly from shooting JPEG images to raw files, or from raw files to simultaneous raw and JPEG capture. I find it hard to imagine that many medium format camera users would want to move away from raw files in many situations. Fortunately, this button can be set to Optical Preview (depth of field preview) or Digital Preview. Digital Preview captures an image at the selected settings for examination on the camera’s screen, but it isn’t written to the card.
The Illumination button can be used to trigger a compatible flashgun to emit a modelling flash or a test flash. Meanwhile the AF button can be set to allow back-button focusing, where the AF function is removed from the shutter release and the Preview Dial around the shutter release can be used to access Optical or Digital Preview.
There are however, three User mode settings can be saved for access via the main mode dial. It’s also possible to save a new name for each User setting to help remind you of the key features. However, this name is only shown briefly on the main screen after turning to the option on the mode dial and it isn’t displayed on the information screen that appears when OK is pressed – the original name, User1, User2 or User3, is shown instead. I suspect this could be rectified by a firmware upgrade.
Like the 645D, the 645Z has seals that make it weather and dust resistant. It also has the same deep grip and, despite its larger size and relatively heavy weight (over 1.5Kg without a lens), it feels comfortable in the hand. It really is feasible to use this camera hand-held, and thanks to its impressive sensitivity range it is possible that this camera will be used so more than any other digital medium format camera.
I used the camera with a weather resistant lens mounted for about 30 minutes in persistent drizzle and didn’t encounter any problems. Despite the water on the grip and covering the buttons and dials it continued to function correctly, and I was able to keep a good grip on it.
At first glance it may seem that those with small hands may struggle to adjust some settings on the camera, but rather than needing to press a button while simultaneously scrolling a dial, most adjustments can be made either with a single press to select the desired option and then using a dial or repeated pressing of a button.
As the user interface is fairly similar to that of Pentax’s K-series cameras it’s very easy to get to grips with the 645Z, and even those who have never used a medium format camera before will soon feel comfortable using it. That said, the menu looks very dated.
Although there are 27 individually selectable AF points, they are all clustered quite close to the centre of the image frame, so the focus-and-recompose technique comes in handy on many occasions with off-centre subjects.
Being an SLR, the 645Z has a reflex mirror that lifts to allow an exposure to be made. Naturally this is quite a large unit and, while it’s not quite the door-slam of some medium format models, you are certainly aware of its movements. It’s helpful that it’s possible to set mirror lock-up mode directly via a switch on the side of the camera, as this is likely to be used for studio work.
The viewfinder is large and bright, but with 98% coverage it doesn’t quite display the whole image and you can expect to find the odd extra inclusion around the edges of the frame on occasion. The LCD screen is also clear and provides a detailed view, whether composing using Live View mode or reviewing images. The fact that the screen tilts is especially useful when composing images on a tripod in the studio or when out shooting landscapes.
It’s also helpful that the screen’s display can be set to rotate to make it easier to read when shooting in upright format.
While the screen provides a clear view indoors, it is much harder to see outside on the default settings. Pushing the brightness value to the maximum helps, but you’ll need to check the histogram to be sure that the image is correctly exposed.
Performance
The key advantage of having 51 million effective pixels on a medium format sensor is that it’s possible to record lots of detail. Also, because those pixels are relatively large, they generate a strong signal that means noise levels can be kept down. This is immediately apparent in the images from the 645Z – they have a huge amount of sharp detail and little noise at the low to mid-range sensitivity settings.
Even at the highest sensitivity setting (ISO 204,800) noise is controlled comparatively well. There is some coloured speckling visible, but detail appears to be better retained than in images from small format SLRs with such settings. Nevertheless, most photographers will still only want to use it for emergencies as there’s a visible granular texture and colour saturation drops significantly.
Stepping down to ISO 6400 results in images that look significantly better, with plenty of detail, making using this setting realistic. It makes the 645Z much more versatile than the ‘average’ digital medium format camera and it’s feasible that owners might use it handheld to shoot events.
The raw files, which are in the convenient DNG format or Pentax’s own PEF format, naturally have more detail than simultaneously captured JPEGs, and it’s possible to strike a nice balance between detail visibility and noise suppression during post-capture processing.
Thanks to the 645Z’s relative portability the auto white balance and general purpose metering systems are more likely to be used than with some more studio-bound medium format cameras. As we have found with other Pentax SLRs, the Multi-segment metering system (which in this case uses a dedicated 86K pixel RGB sensor) generally behaves well, but it is prone to underexposing when faced with bright subjects or if there are large bright areas in the scene. This is something that the target user of the camera is likely to anticipate and is easily dealt with via the exposure compensation control.
The automatic white balance system also does a good job in a range of natural lighting conditions, but as is often the case, a custom white balance setting is a better bet in artificial light. Given the level of photographic experience that the typical 645Z user is likely to have, many would automatically set a custom white balance anyway, or simply resolve to perfect white balance when processing the raw files.
Similarly, most users are likely to create any image effects themselves rather than use the Custom Image options (Bright, Natural, Portrait, Landscape, Vibrant, Radiant, Muted, Bleach bypass, Reversal film, Monochrome, Cross processing) that tailor the appearance of JPEGs, but they are a fun addition and something we are familiar with from small format SLRs and compact system cameras.
In the Natural setting, the 645Z generally delivers pleasant looking images with natural colours.
While the 645Z’s AF system can’t compete with a high-end small format SLRs, it is pretty impressive considering the size and weight of the elements inside the compatible lenses. It’s much faster than most SLRs’ Live View AF systems, and even in quite low light it homed in on its target decisively with no hunting, though it starts to struggle when subjects get close to the minimum distance. It’s a viable option for hand-held photography.
Image quality and resolution
As part of our image quality testing for the Pentax 645Z review, we’ve shot our resolution chart.
If you view our crops of the resolution chart’s central section at 100% (or Actual Pixels) you will see that, for example, at ISO 100 the Pentax 645Z is capable of resolving up to around 38 (line widths per picture height x100) in its highest quality JPEG files.
For a full explanation of what our resolution charts mean, and how to read them, check out our full explanation of our camera testing resolution charts.
Examining images of the chart taken at each sensitivity setting reveals the following resolution scores in line widths per picture height x100:
JPEG
Full ISO 100 image. See 100% crops below:
ISO 100. Score: 38. Click here to see full resolution image
ISO 200. Score: 38. Click here to see full resolution image
ISO 400. Score: 38. Click here to see full resolution image
ISO 800. Score: 38. Click here to see full resolution image
ISO 1600. Score: 36. Click here to see full resolution image
ISO 3200. Score: 36. Click here to see full resolution image
ISO 6400. Score: 36. Click here to see full resolution image
ISO 12800. Score: 34. Click here to see full resolution image
ISO 25600. Score: 32. Click here to see full resolution image
ISO 51200. Score: 28. Click here to see full resolution image
ISO 102400. Score: 24. Click here to see full resolution image
ISO 204800. Score: 18. Click here to see full resolution image
Raw
ISO 100. Score: 38. Click here to see full resolution image
ISO 200. Score: 38. Click here to see full resolution image
ISO 400. Score: 38. Click here to see full resolution image
ISO 800. Score: 38. Click here to see full resolution image
ISO 1600. Score: 38. Click here to see full resolution image
ISO 3200. Score: 36 Click here to see full resolution image
ISO 6400. Score: 34. Click here to see full resolution image
ISO 12800. Score: 32. Click here to see full resolution image
ISO 25600. Score: 28. Click here to see full resolution image
ISO 51200. Score: 24. Click here to see full resolution image
ISO 102400. Score: 20. Click here to see full resolution image
ISO 204800. Score: 16. Click here to see full resolution image
Noise and dynamic range
We shoot a specially designed chart in carefully controlled conditions and the resulting images are analysed using DXO Analyzer software to generate the data to produce the graphs below.
A high signal to noise ratio (SNR) indicates a cleaner and better quality image.
For more more details on how to interpret our test data, check out our full explanation of our noise and dynamic range tests.
Here we compare the Pentax 645Z to the Nikon D810, Canon 5D Mk III and Sony Alpha 7R.
JPEG signal to noise ratio
At the 645Z’s base ISO100 sensitivity, its 51.4MP sensor manages to produce cleaner images than the 36.3MP D810 and 36.4MP Alpha 7R. The 22.3MP 5D Mark III is the camera to beat though, providing the highest signal to noise ratio up to ISO1600. At ISO3200 Pentax takes the lead and the gap widens as sensor sensitivities increase, demonstrating the 645Z’s ability to generate clean images in low light.
Raw signal to noise ratio
Analysing the 645Z’s raw files (after conversion to TIFF) we see the same trend as shown in the JPEG results, with Pentax and Canon vying for top honours. At ISO100 the D810 and Alpha 7R are close rivals, but images become progressively noisier than those from the 645Z at higher sensitivities. This could be due in part to the 645Z’s sensor being comprised of larger (5.3-micron) photosites offering potentially higher light sensitivity than the 4.88-micron photosites on the D810 and Alpha 7R’s sensors.
JPEG dynamic range
All the cameras manage very high JPEG dynamic range scores and are evenly matched up to ISO1600. Here the D810 and Alpha 7R’s scores start to fall more sharply than the 645Z and 5D Mark III’s results, which in turn follow the same trend at ISO3200. At ISO6400 the 645Z starts to establish a clear lead and maintains it up to its maximum ISO204,800 sensitivity.
Raw dynamic range
Converting raw files to TIFF for analysis reveals more pronounced differences in dynamic range than JPEG images reveal. Here the 645Z is clearly superior to the full-frame competition throughout the sensitivity range, indicating that it’s capable of recording the widest range of tones.
Sensitivity and noise images
JPEG
Full ISO 100 image, see 100% crops below.
ISO 100. Click here for full resolution image
ISO 200. Click here for full resolution image
ISO 400. Click here for full resolution image
ISO 800. Click here for full resolution image
ISO 1600. Click here for full resolution image
ISO 3200. Click here for full resolution image
ISO 6400. Click here for full resolution image
ISO 12800. Click here for full resolution image
ISO 25600. Click here for full resolution image
ISO 51200. Click here for full resolution image
ISO 102400. Click here for full resolution image
ISO 204800. Click here for full resolution image
Raw
ISO 100. Click here for full resolution image
ISO 200. Click here for full resolution image
ISO 400. Click here for full resolution image
ISO 800. Click here for full resolution image
ISO 1600. Click here for full resolution image
ISO 3200. Click here for full resolution image
ISO 6400. Click here for full resolution image
ISO 12800. Click here for full resolution image
ISO 25600. Click here for full resolution image
ISO 51200. Click here for full resolution image
ISO 102400. Click here for full resolution image
ISO 204800. Click here for full resolution image
Sample images
Click here for full resolution image
Images are usually pleasantly natural straight from the camera at the default settings.
Click here for full resolution image
This bright scene required 1EV of positive exposure compensation to avoid underexposure.
Click here for full resolution image
This shot taken with the Pentax 120mm macro lens shows how restricted depth of field can be at f/16.
Click here for full resolution image
Here’s the f/22 version which has a slightly sharper background.
Click here for full resolution image
The detail in the stitching of these boots is very impressive.
Click here for full resolution image
Using the automatic white balance setting produced a slightly cool image in the dappled light here.
Click here for full resolution image
Using the daylight white balance setting produced a slightly warmer image.
Click here for full resolution image
It’s a little on the large side for street photography, but the 645Z is capable enough.
Click here for full resolution image
Noise is extremely well controlled at ISO 6400.
Click here for full resolution image
It’s pretty good at ISO 204,800 as well, but there’s a drop in colour saturation.
Click here for full resolution image
It’s useful to be able to shoot black and white JPEGs while recording full-colour raw files for conversion.
Click here for full resolution image
The metering system has coped well with this bright scene.
Click here for full resolution image
Another well exposed images with nice, vibrant colours.
Verdict
In the days of film photography, medium format cameras weren’t just the preserve of professional photographers, many enthusiasts used them as well. Just as with digital photography, the larger frame brought better quality images that could be blown up to bigger sizes.
Sadly, the price of the average digital medium format camera puts it well beyond the reach of most enthusiasts. At around £7,700/US$9,700/AU$12,700 for a camera body and 55mm lens the Pentax 645Z is still too expensive for most enthusiast photographers, but it costs just a fraction of what a comparable Hasselblad kit would set you back, so there is lots of interest amongst experienced photographers.
Despite being at the ‘more affordable’ end of the digital medium format camera market, the Pentax 645Z gives a very good account of itself. It’s a solidly built camera with weatherproof and dustproof seals that make it safe to use outside of the studio. It’s not the lightest camera in the world, but it has chunky, comfortable grips that make it pleasant to use hand-held. The white balance, autofocus and exposure systems also work well (although you need to look out for bright areas triggering underexposure) and its not far off being a ‘point-and-shot’ medium format camera if you want it to behave in such a way.
In addition, the average enthusiast photographer who knows his or her way around a mid-to-high-end SLR will find that they quickly get to grips with its control layout and menu arrangement.
The controls and menus are also responsive and there are some useful features such as the ability for the screen display to rotate when the camera is turned for upright images. Live View technology is novel on a medium format camera and its seems a very logical addition. Medium format cameras are often used mounted on a tripod and in the studio, both of which make using Live View viable. It’s a shame that Pentax has opted to give the 645Z a tilting screen rather than a full articulating one, which would make using Live View even more convenient.
We liked
The step up to medium photography can be daunting, but Pentax has made it much easier by using a similar interface for the 645Z as it does for its K-series SLRs. It doesn’t take long to feel confident using the camera and the large grip, fast autofocusing system and conveniently laid out controls make it easy to use hand-held.
I also really liked being able to compose images on the rear screen when the camera was in the studio, it seems a natural progression from a waist-level finder on a medium format camera.
We disliked
It’s great to have quick access to features such as mirror lock-up, which has a dedicated switch, but there are a few controls on the top of the camera that are likely to be superfluous for many 645Z users and it’s a shame that there aren’t more customisation options available for users to set-up the camera to meet their own specific requirements.
The menu also looks very dated.
Final verdict
The main aim of using a medium format camera is to produce higher quality images than is possible with a small format camera and the Pentax 645Z certainly delivers in this respect. Images have a superb amount of detail and colours are generally natural, yet vibrant straight from the camera. As mentioned earlier, you need to keep an eye on the exposure when there are bright areas in the scene, but that well within the capability of the type of photographer who will be attracted to the 645Z.
Another benefit of having such a large sensor is that it’s possible to restrict depth of field dramatically. This is immediately apparent as soon as you start shooting with the 645Z and many photographers will find that they need to use smaller apertures than they are used to in order to produce a wide enough sharp area.
It will be very interesting to see how the 645Z sells, especially now that we have tiny full-frame compact system cameras like the Sony Alpha 7R and versatile high-resolution SLRs like the Nikon D810.
Powered by WPeMatico