Pentax 645D at a glance:
- 40-million-pixel sensor
- Pentax 645AF2 lens mount for old and new lenses
- Magnesium-alloy body
- 3in, 921,000-dot LCD screen
- 77-segment metering system
- 14-bit raw files in DNG or PEF format
- In-camera HDR
- Street price around £8,999 (body only)
It has been at least five years since Pentax first announced its medium-format digital camera, but now it has finally arrived. Although many users of the original film 645 may have already switched across to other digital bodies, now it is time to dust off those old lenses and put them to good use. Unlike back in 2005 when the Pentax 645D was first suggested, the digital medium-format market is now maturing and is principally dominated by Hasselblad and Phase One. The Pentax 645D has long been envisaged as an affordable alternative for those looking for a high-resolution studio or field camera but, with a body-only price of £8,999, or £9,999 with the new 55mm f/2.8 lens, it comes directly up against the latest Hasselblad H4D-31.
Digital medium-format cameras principally have a size advantage over their 35mm-based cousins. The sensors are physically larger and have far more pixels, allowing them to capture greater detail and tone. As with digital SLR cameras they are not tied to an exact sensor size, and so this varies between models, giving slight variations in the focal magnification of lenses between around 0.64x and 0.8x. This means that a 50mm lens becomes a wideangle, although not as wide as they would appear on 120 rollfilm, medium-format models.
What the Pentax 645D sets out to offer is a more consumer-friendly medium-format experience, with much of the feature set and layout transferred from the company’s popular K-7 DSLR model. This should mean that those looking to enter the medium-format market for the first time will have no problem adapting to the controls, while previous 645 owners will feel quite at home.
Features
At the heart of the Pentax 645D is the Kodak 40-million-pixel CCD sensor. This outputs 7264×5440-pixel images in a choice of 14-bit raw files in PEF or Adobe DNG format, as well as JPEGs. At 44x33mm, the sensor is a little short of the full 56×41.5mm frame size of the original 645 film camera, but it is roughly 1.7x larger than a 35mm sensor.
This means the attached lenses have a 1.3x crop factor compared to the original 645, which incidentally is a 0.79x crop factor when compared to 35mm.The power behind the 645D is Pentax’s Prime II imaging processor, which also features in the company’s current DSLR models from the K-x up to the K-5.
Although on the DSLR models this processor facilitates HD movies, on the 645D it is purely focused on churning through the 14-bit A/D conversion of the mammoth files, which can be up to 70MB a time.
It also gives a more conservative ISO range of 100-1600 as for this type of camera it is far more important to offer quality within a smaller range than any high ISO extended settings. The camera also features dust removal by process of supersonic vibration (DR II) to remove any particles that settle on the sensor, and a Dust Alert system that uses the LCD screen to highlight where on the sensor the dust has settled.
The metering comprises a 77-segment system to allow for more accurate readings in difficult lighting situations, which appears to have been taken straight from the K-7. There’s a choice of spot and partial metering options for more selective readings, and an exposure compensation range of ±5EV. Autofocus comes in the form of the new SAFOX IX+ (also shared by the K-5). This provides 11 selectable AF points with all but two being cross-type sensors. For simplicity, an auto, single, three-point or five-point array can also be selected. White balance control comprises nine presets, which are daylight, shade, cloudy, four types of fluorescent light, tungsten and flash, plus manual and colour temperature settings. All come with fine-tune adjustment.
The shooting-mode dial offers a familiar array of options for regular Pentax users, with the standard program, shutter priority (Tv), aperture priority (Av) and manual accompanied by sensitivity (Sv), shutter and aperture (TAv). There is also a bulb mode, flash sync (X) ,which syncs at 1/125sec, and User setting. It will come as a slight relief for many that this hasn’t been tarnished with a full auto or a series of scene modes – this isn’t a camera for those looking to point and shoot, after all.
There is, however, the familiar green button on the rear that allows a quick auto setting on pressing. Hidden in the menu is the addition of in-camera HDR capture and dynamic range expansion settings, plus a series of in-camera post-capture effects ranging from raw conversion and resizing to digital filters. The viewfinder offers a 98% field of view, and although there is just a 0.62x magnification with the new 55mm lens, it is still a nice large view.
There’s also a large rubberised dioptre adjustment that surrounds the finder, making it easy to fine-tune the focus for your eyesight. The rear 3in LCD screen, with a very respectable 921,000-dot resolution, features brightness and colour adjustments via the menu. The LCD screen can also display a digital level for both pitch and roll, so you can ensure that the camera is completely level before taking your shot.
The 645D features dual SD slots that accept the high-capacity SDHC cards. The camera can save the same image simultaneously to both slots, different formats to each, or you can have one card as a reserve. The decision to use SD over CompactFlash seems a strange one for such a large-bodied camera, especially as there is currently no support for the latest high-speed and mega-storage SDXC cards – although this could be addressed with the aid of a firmware update. CompactFlash is still the preferred format for high-end cameras as it has offered faster write speeds and greater capacities, which has only really been addressed by the new SDXC cards. However, SD cards are now used throughout the K-series range so this provides continuity.
The actual write time for a file to be saved onto the card, using a SanDisk Extreme III SD, is around seven seconds for JPEG, eight seconds for raw or 11 seconds for raw+ (raw + JPEG). Such long save times are unsurprising considering the huge file sizes being transferred ,but thankfully the camera doesn’t lock up during this time so you are free to continue shooting after around a second.
If you want to review the image, however, you must wait for up to five seconds for the image to first display on the LCD screen, which can slow down your shooting, especially for portraits. The continuous shooting mode gives a burst speed of around 1.1fps, which can be maintained for up to 19 shots in JPEG or 15 in raw+.
Lenses
The 645D uses the 645AF2 bayonet mount, but is also compatible with older 645AF and 645A lenses. For this review I used 150mm f/3.5 and 200mm f/4 lenses, courtesy of MrCad in Croydon (www.mrcad.co.uk), as well as the new D FA 645 55mm f/2.8AL SDM lens that comes as part of the 645D kit. Remember that as the sensor is smaller than the original 645, there will be a crop factor of 1.3x – meaning that lenses will appear longer than they would have done on the old 645 model. The 55mm lens is therefore a 43.5mm (in 35mm terms) or 72mm (in old 645 terms). The 150mm (120mm in 35mm) made a great portrait lens and you can pick one up for around £250.
The aperture ring was fully active, but switched back to the camera when placed in the A setting, and despite being fully manual focus it was easy to find focus thanks to the larger viewfinder and added security from the focus confirmation in the viewfinder. The 200mm f/4 lens is more useful as a mid-range telephoto optic for outdoor shooting due to the longer close-focus, but is still very easy to use with the camera on a tripod or monopod.
The beauty of this lens mount is that not only will many users already have a collection of lenses, but also those who don’t can pick up some great second-hand examples for very little, especially the older manual versions. It’s worth getting in quick, though, because once people start to buy into the 645 system again, prices are likely to rise. There is now a back catalogue of around 30 Pentax 645 lenses in various forms from 35mm to 600mm, including a number of zooms, making it an extensive system for the landscape or studio photographer.
Build and handling
The body has a magnesium-alloy casing and die-cast aluminium chassis for strength. This is weather-sealed against dust and moisture, and is designed to work in temperatures as low as -10°C, reinforcing its potential to be far more than just a studio model. The camera certainly feels solid in the hand and, although fairly weighty, it is only around 150-200g heavier than a Nikon D3X or Canon EOS-1Ds DSLR with battery. The 645D body also benefits from a substantial right-hand grip, which allows you to feel fully in control of the camera, even when holding it with one hand. In addition to the regular tripod bush on the underside of the body, there is a second on the side, allowing you to mount the camera directly on the tripod in portrait orientation.
On the top of the body, the row of quick-access buttons include SD1/SD2 buttons, which allow you to quickly change the type of file being recorded to the respective card. There’s also a raw button that allows a quick swap between raw and JPEG formats, and a bracketing selection. A mirror-up dial to the right of the prism certainly comes in handy for long-exposure shots. The large shooting-mode dial is heavily rubberised for easy grip, but also has a central lock button to avoid accidental mode changes.
The 3in LCD screen takes up a large portion of the rear of the camera, but to its right sits a series of easy-access buttons, including the green button that offers a quick auto setting. Quick auto seems a little out of place on this type of camera. A four-way D-pad control is used for the main navigation, allowing menu access as well as AF point selection.Underneath the LCD screen are further quick-access buttons for flash, colour, drive and white balance. The selection dials on the front and rear are placed for easy finger and thumb access.
All the controls and buttons are chunky and positive to press, making the operation easy and instinctive, so even in gloves most features can be easily accessed. The whole layout looks and feels like Pentax’s K-7 DSLR, scaled up to fit the 645D’s larger body, which overall is no bad thing. The menu is clear and it is easy to find the required function, once again much like the recent DSLR menus. Although it is not as sleek, colourful and icon friendly as some, it is functional nonetheless.
The new D FA 645 55mm f/2.8AL SDM kit lens for the 645D, which equates to 43.5mm in 35mm terms, is weatherproofed to match the body and features a completely rounded diaphragm for better bokeh. It offers a nice big rubberised focus ring and fast, quiet autofocusing.
White balance and colour
Image: The level of detail from the images is breathtaking, although raw files offer more potential with processing
For outdoor and general landscape shots, the auto white balance setting produces a rich set of colours that require no correction. In the studio, however, neither the auto nor the flash presets deliver neutral tones, coming up either too warm (with the flash setting) or too cool (AWB). That said, the custom white balance makes it very easy to set a manual white balance from a grey card and, once this is stored, images are much more neutral. Under tungsten lights the camera gives the option, via the menu, to neutralise or maintain the natural warmth. This can be very handy if you are trying to give your shots a certain atmosphere.
Colours from default JPEG images (the natural setting) are rich and punchy without being oversaturated. There is a range of colour modes to choose from depending on your preferences: bright punches up the saturation a little more, while landscape really boosts the blues and greens. There is also a portrait setting that optimises for skin tones, a muted setting for subtle colours, vibrant for even more punch, monotone for greyscale with eight filters and, interestingly, reversal film to give a vibrant colour transparency look.
Metering
The 77-segment multi-pattern metering system has already proved successful in the K-7, but in the 645D it really seems to excel. Images display a generally even range of tones that on occasion seem stronger on the darker tones, but always avoid losing any shadow detail. In most cases the evaluative metering tends to underexpose by between a half and a full stop, although at times this is preferable to help bring out the richness of the image and means that highlights are retained. From raw files it is possible to extract plenty of extra detail from even the darkest of shadow areas. The metering doesn’t seem to suffer from a tipping point in terms of exposure, as priority seems to be given to the brighter areas.
Image: The metering does underexpose slightly, but there is plenty of detail in the shadows that can be pulled out in processing
To test this I took a series of landscape shots with the bright sky taking up different proportions of the scene. Despite the variations in the histograms, the overall exposure and brightness only changed subtly through the range. Also on offer for more selective metering are partial and spot modes. The partial mode can work as a handy override for the evaluative mode, allowing you to obtain a brighter main subject at the expense of the surroundings.
An alternative is to use the generous 5EV exposure compensation to manually adjust your exposure. Although Pentax was unable to give the exact value, we believe the spot metering gives around a 2% coverage, which gives a very precise measurement from the centre point, although off-centre spot metering can be achieved using the exposure lock button and recomposing.
Autofocus
The SAFOX IX+ is Pentax’s latest AF system and it graces both the new flagship K-5 DSLR and the 645D. It features an 11-point selection, nine of which are cross-type sensors for increased sensitivity. The nine points are placed fairly centrally in the viewfinder, with only the two non-cross-type points edging out to the left and right for any real off-centre focusing.
For ease, this can be switched to just five points, three points, one point or even set to auto selection. This arrangement may not seem that impressive in DSLR terms, and is certainly no match for cameras such as the Nikon D3X, but as most medium-format models use only a central AF point, it is way ahead of the game.
It even allows continuous AF and, although not the quickest, will capably allow you to remain fixed to a moving subject. There is a dedicated AF button on the rear of the camera for those who prefer not to use the half-press method – again, handy for outdoor use with numb or gloved hands.
In poor lighting or low-contrast scenes, the camera struggles to find focus and there is no AF illumination to aid it. In these cases, for speed, it is often best to switch to manual. In regular light, however, it performs without a quibble, locking onto the subject with ease and, using the new SDM lens, zips into focus. Focusing is noticeably speedier when keeping to the nine cross-type sensor points, however. Some photographers are likely to want to keep the camera in manual focus for control and simply use the AF confirmation light in the viewfinder, which flashes red when focus is achieved.
Noise, resolution and sensitivity
Images display pin sharpness using the new 55mm lens, although DSLR users should be aware that depth of field can be very shallow
The detail that can be obtained from a 40-million-pixel sensor of this size is truly breathtaking. When compared directly with similar shots taken on Nikon’s 24-million-pixel D3X, the difference in detail at 100% magnification is starkly obvious – from a full-length portrait the pores in the skin on the model’s face were still crisp on the 645D, while the D3X was running out of pixels.
On our resolution chart, both JPEGs and raw files reached around 38, and with a little extra sharpening and noise reduction, raw could arguably have gone even further. The beauty of the 645D raw files is that, with a choice of both PEF and the standard Adobe DNG file, they are already supported (at least in DNG) by most existing raw software.
Image: Even at the camera’s highest setting of ISO 1600, noise is still well controlled and detail remains well defined
The standard sensitivity range of the 645D is actually ISO 200-1000, with 100 and 1600 considered ‘boost’ settings. There are subtle signs of noise in shadow areas from ISO 400 upwards, but this remains monochromatic and little more than a slight texture right up to ISO 1000. The ISO 1600 setting does start to show some colour noise, but this is still kept to a minimum and can be largely removed in processing.
Resolution charts: These images show 72ppi (100% on a computer screen) sections of images of a resolution chart, captured using a Pentax 55mm f/2.8 AL SDM lens. We show the section of the resolution chart where the camera starts to fail to reproduce the lines separately. The higher the number visible in these images, the better the camera’s detail resolution is at the specified sensitivity setting.
Dynamic range
From our testing and measurements using DxO’s testing methods we believe the maximum dynamic range to be around 12.5EV, which is in keeping with most recent DSLRs. The 645D also boasts methods for extending the dynamic range in the form of its dynamic range expansion and HDR settings. The dynamic range expansion offers either high illumination or low illumination for highlight or shadow priority. This works well to produce a nice subtle effect on JPEG images. The HDR mode will take three images in quick succession and combine them in-camera with either a standard or strong effect, although the strong is best avoided for any serious work.
Image: The dynamic range expansion offers high or low illumination for lifting either highlights or shadow
Viewfinder, LCD and Live view
Aside from the image quality, the viewfinder is perhaps the best part of a medium-format camera. It is larger than a DSLR viewfinder, making it much easier to manually focus and compose your shot. Despite the apparent size of the 645D’s viewfinder, it offers only a 98% field of view, which seems unusual for such a product – especially as its main rival (the Hasselblad H4D-31) is offering full 100% coverage. It is, however, a step forward from the old 645N film model, which gave only 92/93% coverage from its viewfinder, and most will hardly notice the 2% difference.
The rear LCD is a high-resolution device that, apart from appearing slightly dark, gives great colour definition and detail. When not being used for reviewing images, the LCD screen can display more shooting information by pressing the disp button. This gives much the same information as shown on the top LCD panel, but in a clearer and more graphical form. The screen can also display the digital level, which gives an aircraft simulator-style display for pitch and roll, to help you keep the camera level.
The 645D doesn’t offer a Live View display of any kind, nor does it offer video. While this may seem surprising considering the 645D’s similarities to the K-7, it is the Kodak CCD sensor that is responsible for their absence. The depth of field preview can be used to preview an image on the LCD screen, but this is essentially achieved by taking a shot that is not saved to the card.
The competition
The most logical competitor for the Pentax 645D would be the Hasselblad H4D-31, as this offers the same size sensor physically, although with fewer pixels (31 million). Its current price is almost identical to that of the 645D, including a lens. Hasselblad also offers the more resolute H4D-40 for around £13,000 with lens.
Image: Hasselblad H4D-31
Image: Nikon D3X
The other competition for the 645D will come from high-end DSLRs such as the Canon EOS-1Ds Mark III and the Nikon D3X. Although these cameras offer a very different proposition and only around half the 645D’s resolution, they are still highly regarded for studio and fashion work. For this reason there may be occasions when a photographer would be choosing between a pro 35mm DSLR and a medium-format model, especially considering that their prices are also only around half of the 645D, meaning you could buy a complete setup for the price of the Pentax.
Our verdict
The 645D will no doubt attract a niche audience, as the almost £10,000 price tag is firmly out of reach of most amateur users. Interestingly, though, many of the features seem to be catering for a more consumer-level user, with its DSLR-styled additions and a host of auto modes. It’s not perfect, but it does have benefits and is bound to prove popular with landscape and wedding photographers alike.
As a professional tool the Pentax 645D offers an interesting alternative to the Hasselblad, and a huge increase in image quality from the Pro 35mm models. It is certainly at the affordable end of medium-format models, with a feature set and handling that either matches or betters the competition in many areas – and yet there was the potential for it to be even better, had it included Live View or even just a faster write and preview time.
For many, a professional-level DSLR still has more versatility but, as long as you’re not looking for speed, the Pentax 645D is a pleasure to use and the results certainly show Pentax’s experience in the medium-format sector.
Pentax 645D – Key features
Large rubberised eyepiece
This is a decent size, helping to fully surround the eye and block out external light when composing
Rear 3in LCD screen
The high-resolution, 921,000-dot screen makes reviewing shots a pleasure, and also displays shooting information
Top LCD display
A nice large mono display provides all the relevantshooting information, including file formats for each SD card
The ‘green’button
Brought over from Pentax’s DSLR range, this allows a quick auto exposure to be achieved
Raw file handling
The 645D offers raw files in a choice of Pentax PEF or the universal Adobe DNG format, at 14-bit. This gives users the option to output to almost any software
Dust reduction
Fitted with the Dust Reduction II (DRII) system, the camera uses supersonic vibration to shake dust from in front of the sensor on start up/shut down
Digital level gauge
By pressing the disp button, the LCD screen switches to a digital spirit level gauge reminiscent of an aircraft simulator for vertical and horizontal alignment
Picture modes
This series of presets allows the colouration and contrast of the images to be adjusted and fine-tuned if required. Modes include a new reversal film option.
