Pentax 645Z Review

July 30, 2014 | Mark Goldstein |


The Pentax 645Z is a medium-format DSLR camera with a 51.4-megapixel CMOS sensor with no low pass filter, offering an imaging area of 43.8mm x 32.8mm which is 1.7x larger than a 35mm full-frame sensor. The dust and splash resistant Pentax 645Z has a sensitivity range of ISO 100-204,800, a SAFOX 11 phase-matching AF module with 27 sensor points (including 25 cross-type sensors), PRIME III processing engine, 86,000 pixel RGB metering sensor, a tiltable 3.2-inch LCD monitor with 1,037K dot resolution, an optical viewfinder with 98% frame coverage, 3fps continuous shooting, a 10-frame raw buffer, and dual SD memory card slots. The 645Z can also record Full HD video clips (60i/30p) and allows interval video recording of 4K-resolution images (in Motion JPEG or AVI video format). The Pentax 645Z is officially priced at £6,799.99 / $8,499.95 body only, or £7,699.99 with the DFA 645 55mm F2.8 lens.

Ease of Use

The Pentax 645Z is actually smaller and lighter than you might think, measuring 117(H) x 156(W) x 123(D) and weighing just over 1.5Kg with the battery or memory card fitted. You don't actually pay too much of a size or weight penalty for choosing the medium-format 645Z, certainly not when comparing it to other similar cameras, although it obviously also depends on which lens you choose to use. We reviewed the 645Z with the DFA 645 55mm F2.8 lens, which adds another 416g to the overall system weight.

You can instantly tell that the 645Z is a serious camera as soon as you handle for the first time. This is mainly due to the 645Z's magnesium alloy frame and die-cast aluminium body. The 645Z is dust, cold and water resistant, thanks to a system of 76 special seals used throughout the design, and it can operate at temperatures as low as -10°C. This shows itself most obviously via the battery compartment and the memory card slot. The 645Z features a shutter unit that provides a fast top shutter speed of 1/4000th second and an impressive 100,000 shutter release life-span. The 645Z omits the traditional optical anti-aliasing filter in the camera to help maximise image quality and resolution.

The smc PENTAX DFA 645 55mm F2.8 lens that we were sent for review along with the 645Z provides a field of view roughly equal to a 43mm lens. It also features a weather-resistant construction designed to minimise the intrusion of water and moisture into the lens barrel, and there's a special SP coating which repels dust, water and grease and makes it easy to wipe off fingerprints and cosmetics. Consequently it feels well-matched to the 645Z, and is probably the lens that a lot of 645Z owners will buy first.

As it's clearly aimed at the experienced shooter, the Pentax 645Z is a complex camera in terms of functionality and the number of external controls that it offers, with a lot of them having more than one function. Despite the presence of so many buttons and switches, though, the Pentax 645Z doesn't feel too cluttered or intimidating, as it cleverly adopts many of the features and conventions found on the company's DSLR cameras.

The Pentax 645Z has a deep, contoured handgrip on the right-hand side, coated in a rubberized compound to aid grip, that enabled us to use three fingers to hold it and a right forefinger to operate the shutter button, much like a DSLR. There is a generous contoured area on the rear where your right thumb sits, with the rest of the body finished in a textured matt black. The shutter release action on the Pentax 645Z is pretty quiet given the size of its mirror, which makes the 645Z well suited to more candid photography. The Mirror Up dial makes it easy to toggle this feature on and off, helping to avoid any unwanted vibrations particularly when shooting long exposures.

Pentax 645Z Pentax 645Z
Front Rear

On the bottom of the 645Z in the base of the handgrip is a weather-sealed battery compartment, housing the same rechargeable 1860mAh D-LI90P lithium-ion battery that's used by the K-3 DSLR camera. The 645Z managed around 650 shots using the supplied rechargeable Li-ion battery before being depleted. There's also a metal tripod mount that's perfectly in-line with the centre of the lens mount, plus two additional tripod mounts on each side of the camera for vertical shooting.

On the left-hand side of the 645Z is a weather-sealed SD / SDHC / SDXC dual memory card compartment that's compatible with SDXC UHS-1 speed cards. If you use an optional FLU memory card in the 645Z, you can release the 645Z's shutter, check the live-view image, and browse and download the images recorded on the card using a smartphone. Note that the FLU card is currently limited to 16Gb in size. Underneath is a large vertical flap covering the Mic port for connecting an external microphone, DC In, USB 3.0 and HDMI connectors. The HDMI port allows you to connect the 645Z to a high-def TV set, but only if you purchase an optional HDMI mini-cable. Located on the right-hand flank is the remote cable release connector.

On the top-left of the Pentax 645Z is a column of four buttons. The RAW button instantly sets the image quality to whichever RAW format is selected in the menu system (either Pentax's PEF format or Adobe DNG), useful if you are shooting in JPEG and want to quickly switch to RAW mode for a particular image. Located underneath are the Continuous Shooting and the Autofocus Area button, and finally the Lock button which prevents mistaken operation of certain dials and buttons when shooting (it can also be configured to lock all buttons except the shutter release).

The Pentax 645Z has a lockable shooting mode dial on the top-left of the camera, which allows you to select either one of the advanced mode like Aperture-priority, Shutter-Priority and Manual, or the more point-and-shoot Auto and Program modes. There are no scene modes on this camera, signaling its intent as a serious photographic tool.

You'll instantly notice that the 645Z has a couple of unusual shooting modes that you won't have seen before on any other camera. These are the Sensitivity-Priority and Shutter & Aperture-Priority modes, and they are genuinely useful additions. Sensitivity-Priority automatically selects the best combination of aperture and shutter speed for your chosen ISO speed. The sensitivity can be shifted instantly (in 1/2 or 1/3 steps) by turning the rear control dial. This allows you to quickly select an ISO speed, without having to access the menu system, which is very useful in rapidly changing light conditions.

In the Shutter & Aperture-Priority mode the camera selects the most appropriate ISO speed for a shutter speed and aperture combination, allowing you to use ISO sensitivity as a third factor in determining the correct exposure. As digital cameras have always offered the unique ability to instantly change the sensitivity, it's surprising that Pentax are still one of the few manufacturers to allow you to use ISO in this way. At the base of the shooting mode dial is a switch for selecting one of the three available metering modes.

On the right-hand side of the top of the 645Z is the tactile shutter button, surrounded by the on/off switch. This has a third setting, which by default activates the traditional Depth of Field Preview function, stopping down the lens so that you can see the effect of your chosen aperture. Located in front of the shutter button is one of the e-dials, predominately used to change the shutter speed, while behind it are the Exposure Compensation and ISO buttons - these commonly-used functions are ideally located for easy access.

Pentax 645Z Pentax 645Z

Tilting LCD Screen

Pentax have incorporated a traditional top LCD panel which displays a comprehensive amount of information about the current camera settings, including the shooting mode, current aperture or shutter speed, flash mode, battery level, number of remaining frames and drive mode. A similar amount of settings are also displayed in the viewfinder. In addition, when you turn the 645Z on or change the shooting mode, a graphical overview of how that mode operates is briefly displayed on the rear LCD screen. The Pentax 645Z does a very good job of providing easily understood information about the settings that it's using.

The Pentax 645Z has a traditional eye-level optical TTL viewfinder which offers 98% scene coverage and 0.62x magnification with the DFA 645 55mm F2.8 lens. The viewfinder is bright and free of any distortions or aberrations, making it suitable for both auto and manual focusing. It also features a Natural-Bright-Matte III focusing screen to improve focusing accuracy during manual-focus operation. The in-finder status LCD runs horizontally along the bottom and it shows most of the camera's key settings.

On the rear of the 645Z is a the large 3.2 inch LCD screen. The 645Z's LCD screen has a very high resolution of 1,037K dots, wide viewing angle and it's gapless design helps it to remains visible outdoors in all but the brightest of conditions, making it one of the better LCD screens that we've seen. The brightness, saturation and colour temperature of the screen can be modified if you think it doesn't match that of your calibrated computer monitor. The LCD screen features a tilt mechanism which can be moved 35° downwards and 125° upwards, making it possible to shoot at low and high angles and high angles while looking at the Live View display from a more comfortable position.

The rear screen also doubles as a comprehensive status display, which can be called up by pressing the OK or Info buttons in record mode. If you then press the Info button again, you can also change all the settings right on the screen using a combination of the navigation pad and the rear e-dial. This ingenious solution spares you the pain of having to enter the menu, and makes most setting changes via the LCD screen very simple.

Located to the left and right of the optical viewfinder are handy dials for setting the auto-focus type and live view mode respectively. The Pentax 645Z can record 1080 HD footage, recording high-definition video at 1920 x 1280 pixels at 60i/50i/30p/25p/24p or 1280 x 720 pixels at 60p/50p/30p/25p/24p in the Motion JPEG (MOV) format. An innovative interval movie mode captures a series of 4K-resolution movie clips (3840 x 2160 pixels) at a fixed interval. The maximum size of a single video clip is either 4 gigabytes or 25 minutes.

There's a built-in microphone for stereo recording and a socket for connecting an external stereo microphone. You can adjust the audio recording level manually and monitor sound levels during microphone recording. It also has an HDMI port for playback on a HD TV, using the industry-standard HDMI mini-out connection, but note that you'll need to purchase a suitable cable separately. You can also still connect the 645Z to a standard TV set via NTSC/PAL.

You can autofocus during movie recording, but unfortunately you can't set the aperture from the camera during recording, only before, so you will want to use lenses that have an aperture ring if possible. The 645Z can be set to Auto Aperture Control, which removes the flexibility of being able to set the aperture yourself but at least enables the camera to change it during recording to suit the subject matter. The shutter speed cannot be set by the user in movie mode either, so you will have to rely on the camera's auto-exposure system while filming.

Pentax 645Z Pentax 645Z
Top Side

To engage Live View for stills, you have to set the switch to the Camera icon, then press the red LV button. You can use the Live View mode to hold the 645Z at arm's length or mount the camera on a tripod, with a single press of the LV button on the rear displaying the current scene on the LCD screen. Focusing is achieved by pressing the small AF button on the rear of the camera or by half-pressing the shutter-button. Alternatively you can use manual focus in Live View mode, with up to 10x magnification available via the OK button to help you fine-tune the focus (you can also use the OK button to magnify the subject by up to 10x when Auto Focus is on).

Most of the main camera settings are displayed in Live View, including a helpful electronic level that helps to keep your horizons straight. You can change the aperture, shutter speed, exposure compensation, ISO speed and a number of other settings when Live View is activated. Live View is fine for use with stationary subjects, but forget it if you want to track a moving subject. The AF system in Live View mode takes a couple of seconds to lock onto the subject, making it much better suited to subjects that don't move. The Face Recognition AF mode works quite well, as promised quickly identifying up to 16 people in the frame, but again it takes a couple of seconds to lock onto a non-moving subject. More impressively Live View can be used in the continuous shooting mode with no restrictions on the 3fps rate, as the 645Z sets the mirror to the lock-up position.

Located to the right of the LCD screen are the rear e-dial, mainly used for changing the aperture, with an AE-L button on the far right, handily placed for locking the exposure. Underneath is a rather innocuous looking button with a small green dot that's unique to Pentax cameras. It has two uses - firstly, when shooting in Manual mode, a single push of the green button allows you to instantly set the correct exposure for the subject, as calculated by the camera, useful if you need a starting point for your own exposure. Secondly, the 645Z offers a Hyper Program function which instantly switches to either the Shutter-Priority or Aperture-Priority mode from the Program mode, simply by turning either of the control dials on the grip. Pressing the Green button then returns to the Program mode.

A traditional 4-way navigation pad is split into separate buttons, providing instant access to the drive mode/self-timer, custom image, flash and white balance settings, with the OK button confirming actions. The Pentax 645Z has an Autofocus Area button which allows you to quickly set the AF point to one of the 27 available. Impressively 25 of these are cross-type sensors positioned in the middle, with the centre sensor and two sensors just above and below it designed to detect the light flux of an F2.8 lens. In Playback mode this allows you to toggle between the dual SD cards.

The red LV button turns the 645Z's Live View mode on and off in capture mode, doubling up as the Delete button when playing back your images, with a self-explanatory Play button alongside. Beneath that is the aforementioned Info button is the Menu button which accesses all of the 100+ different menu options that the camera offers, reflecting the fact that this a complex and very customisable camera. Thankfully you will only have to set about half of the settings once and can then forget about them. The menu system has a fairly logical tabbed system with five main tabs, Camera, Movie, Playback, Set-Up and Custom Setting, each divided into several sub-pages, and it's easily readable with a bright display and a large font size making it perfectly visible even in low light.

The Pentax 645Z features a Shake Reduction system via compatible SR lenses. Turn it on via the main menu option and the 645Z automatically compensates for camera shake, which is a slight blurring of the image that typically occurs at slow shutter speeds, providing approximately 3 shutter steps of compensation. The 645Z displays a blur icon in the viewfinder to warn you that camera-shake may occur, regardless of whether or not Shake Reduction is on.

The 645Z offers a Dust Removal II mechanism which automatically shifts the UV/IR reduction filter located in front of the CMOS image sensor at very high speed, shaking the dust off the filter. If you do still notice any dust, there's a neat feature called Dust Alert which is designed to show exactly where the dust is on the image sensor. A vertically and laterally correct image of the sensor shot at f/16 is shown on the LCD screen, indicating exactly where any stubborn dust particles may be lurking. While this feature won't prevent dust from getting onto the sensor, it does provide a quick and easy way of checking for it. In addition Dust Removal can be set to activate whenever the camera is turned on, and you can also use the built-in Sensor Cleaning function to lift the mirror and clean the image sensor with a blower brush or third-party cleaning solution.

Pentax 645Z Pentax 645Z
Memory Card Slot Battery Compartment

The Pentax 645Z's High Dynamic Range (HDR) Capture option takes three images with different exposures, with 3 different strengths on offer, and then records a single image that combines the properly exposed parts of each one, expanding its dynamic range. Similar to Nikon's D-lighting, Sony's DRO, and Olympus' Shadow Adjustment Technology, Pentax's D-Range allows you to correct the highlights (On or Off) and/or the shadows (3 different levels) before taking a JPEG or RAW image. Although this option is always at your disposal, remember that it is meant to be used in strong, contrasty lighting at base ISO. The Pentax 645Z also has a multi-exposure mode that allows you to combine between two and 2,000(!) different JPEG or RAW images into a single photo.

Pentax's Custom Images, similar to Nikon's Picture Styles and Canon's Picture Controls, are preset combinations of different sharpness, contrast, saturation and colour tone settings. You can change the saturation, hue, high/low key, contrast and sharpness for each of the ten options”. The Pentax 645Z additionally offers various Digital Filters, which allow you to quickly apply an artistic effect to a photo before taking it (JPEG images only). Note that applying the Digital Filters slows the camera down somewhat, as it has to process the image for a few seconds after it's taken. The 645Z can also be set to automatically compensate for distortion, peripheral illumination, diffraction and lateral chromatic aberration of certain lenses.

The rather innocuous-sounding AF Adjustment custom function will be of particular interest to current Pentax owners. If you have a collection of older Pentax lenses and you've never been quite sure how accurate they focus when mounted on a camera, this is the function for you. Essentially it allows you to alter the focus of each lens. You can use a focusing target to test if the lens focuses correctly, and if it doesn't alter it slightly using the AF Adjustment option, then test again until perfect focus is achieved. With most other systems you'd have to send the camera and lens off for calibration (and maybe even have to pay for it), but with the 645Z, you can calibrate all of your lenses in the comfort of your own home.

The start-up time of the Pentax 645Z, from turning the camera on to being ready to take a photo, is very quick for at around 1 second. Focusing is quick and reliable even in low-light thanks to the highly sensitive SAFOX 11 phase-matching AF module. Indeed, Pentax claims that the 645Z has ONE OF the largest working rangeS of any medium-format camera on the market (-3 EV to +18 EV) and this was certainly borne out in practice.

It takes about 3 secondS to store a JPEG image at the highest quality setting with no discernible lockup between taking shots, allowing you to keep shooting as they are being recorded onto the memory card. For RAW images the Pentax 645Z takes about 4 seconds to store an image and again there is no lockup between shots. In the continuous shooting mode you can hold down the shutter button and take 3 shots per second for up to 30 JPEGS or 10 RAW files, an impressive performance given the massive 51 megapixel files that this camera produces. The 645Z does lock up for a few seconds once the maximum number of shots is reached, although you can continue to shoot continuously, just at a much slower rate.

Once you have captured a photo, the Pentax 645Z has a good range of options for playing, reviewing and managing your images. You can instantly scroll through the images that you have taken, view 12 thumbnails, zoom in and out up to a magnification of 16x, and see very detailed information about each image by pressing the Info button. You can also delete, rotate, resize, protect and crop an an image, view a slideshow and set various printing options. There is an extensive range of digital effects available which can be applied to JPEGs plus a Custom option to create your own unique effect. The camera shows you a preview of what the effect will look like when applied, and the effect is applied to a copy of your image, thus preserving the original intact.

Save as Manual WB sets the camera's Manual White Balance setting to the colour balance of the current image and Save Cross Processing saves that specific setting as a favourite. Color Moire Correction reduces colour moire and RAW Development converts a RAW file into a JPEG or TIFF with various conversion parameters available. Movie Edit lets you divide or extract segments from your movies. Importantly the Pentax 645Z offers both a brightness and RGB histogram after taking a photo which is a great help in evaluating the exposure, plus any areas that are over-exposed flash on and off in the LCD preview to show you want you should be compensating for with your next attempt. If you have never used a Pentax or medium format camera before, reading the comprehensive but relatively easy-to-follow manual before you start is a good idea. Thankfully Pentax have chosen to supply it in printed format, rather than as a PDF on a CD, so you can also carry it with you for easy reference.