It may be big, but the Pentax 645D manages to remain surprisingly light, thanks to an aluminium die cast chassis, combined with its magnesium alloy outer shell. Although you still probably wouldn't want to have it round your neck all day, at only around 200g weightier than your average full-frame DSLR, it is perfectly possible to take the Pentax 645D out in the field for some photography outside of the studio.
With that last point in mind, Pentax has borrowed elements from the excellent design of its flagship DSLR, the K-5, including full weather sealing and the ability to operate at temperatures as low as -10C, so you can be confident that the camera can withstand the rigours of life on the road.
Partnering the rugged build with ergonomically-shaped, rubberised front and rear grips makes the Pentax 645D very comfortable to shoot with hand-held. Its intuitive interface - which borrows heavily from Pentax's tried-and-tested DSLR designs - also makes it incredibly simple to pick up and start using straight away.
The large top-panel LCD screen provides an overview of your current settings at-a-glance, with further information being displayed on the rear LCD.
Underneath the screen there are fast access buttons to the camera's flash, colour drive mode and white balance options, with further controls lining the right-hand side of the screen and spreading out towards the deeply sculpted rear thumb grip towards the right-hand side of the back panel.
Even more buttons - including dedicated controls for accessing each of the Pentax 645D's dual memory card slots - are located on the elongated top panel that extends to the left of the viewfinder hump.
With such a comprehensive array of large, dedicated controls spread across the camera body, you have fast access to all of the key functions you're likely to need while shooting, and - if you do have to delve into the main menu system for any reason - everything is logically laid out and easy to navigate using the camera's four-way d-pad.
The combination of high-end features and such a simplistic design that, arguably, any photographer could easily master - regardless of experience level - is what makes the Pentax 645D such an appealing camera.