FEATURES
Like the Pentax 645D that it replaces, the 645Z has a sensor that measures 43.8 x 32.8mm (168% the size of a 35mm frame). Sony has provided the sensor rather than Kodak this time, and the pixel count has been boosted from 40 million to 51 million. The anti-aliasing filter is also omitted to boost detail resolution.
Pentax has coupled the sensor with its Prime III image engine, first seen in the Pentax K-3 APS-C-format SLR. This enables up to 10 raw images (or 30 large highest-quality JPEGs) to be shot at up to three frames per second. In addition, the maximum sensitivity setting is ISO 204,800, significantly higher than the ISO 6,400 maximum offered by other medium-format cameras. There’s also a tilting 3.2-inch 1,037k-dot LCD, which is capable of showing a Live View image, and Full HD movies may be recorded. 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.
BUILD AND HANDLING
Pentax has used the same design and control layout for the 645Z as it did for the 645D. The body is covered liberally with controls that give a quick route to key features such as sensitivity, white balance and exposure compensation. However, there’s only fairly limited scope to customise the use of these buttons. The new camera has the same deep grip and, despite its large size and relatively heavy weight, it feels comfortable in the hand.
As the user interface is fairly similar to that of Pentax’s K-series cameras, it’s easy to get to grips with the 645Z. Even those who have never used a medium-format camera before will soon feel comfortable using it. That said, the menu looks dated. As 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.
The LCD screen is clear and provides a detailed view, whether you’re 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 you’re shooting in upright format.
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, which 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 of 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. Stepping down to ISO 6,400 results in images that look significantly better, with plenty of detail, so using this setting is perfectly realistic.
As we have found with other Pentax SLRs, the 645Z’s Multi-segment metering system generally behaves well, but it is prone to underexposing when faced with bright subjects or when there are large bright areas in the scene. 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. In the Natural Custom Image 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 SLR’s, it is pretty impressive considering the size and weight of the elements inside the compatible lenses. Even in quite low light, it homed in on its target decisively with little hunting, although it starts to struggle when subjects get close to the minimum distance.
VERDICT
The Pentax 645Z is a solidly built camera, yet it’s pleasant to use hand-held. It’s not far off being a ‘point and shoot’ medium-format camera if you want it to behave in such a way.
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. Depth of field can also be very limited, which is a potential shortcoming for landscape and macro photography.
OVERALL
We saY: despite being at the more ‘affordable’ end of the medium-format market, the 645Z is solid and weatherproof. it’s also easy to use, and produces superb images with huge amounts of detail.
