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+.
