The Sigma BF: a stunning looking 26.4 MP full frame compact in a radical unibody design

The new $1999 Sigma BF is certainly eye-catching and the minimalist design aesthetic extends from its form factor into the design of its UI.

No hotshoe, no EVF, no memory card slots...It looks different because frankly it is different. Sigma says that its new Sigma BF is the first camera in history to feature a true unibody. That means that each camera is carved out of a single solid block of aluminium, a process that the company says takes seven hours per camera. 

As you would expect from all that effort towards minimalism, controls are simplified too. Sigma also claims another first, the BF being the first mirrorless camera to incorporate haptics into its Dial, Center button, Option button, and Playback button, resulting in minimal physical wear. Indeed, all shooting controls are integrated into just three buttons: one dial, the shutter release, and the power button.

At its centre is a 26.4 MP 35 mm full-frame (35.9 mm x 23.9 mm) back-illuminated CMOS sensor.  This features a native ISO range of 100 to 102,400, and features expanded sensitivity down to 6, 12, 25, and 50.

The BF supports high-resolution 6K and L-Log recording, enabling video production that takes advantage of the wide dynamic range of a full-frame sensor at up to 120 fps. It features 230 GB of internal memory, which will give users 2.5 hours of video (0.5 hours more than its continuous shooting time) at the highest-quality setting, with the USB-C port offering fast charging and data-transfer speeds.

A hybrid autofocus system combines phase detection and contrast detection, and utilizes what the company says are state-of-the-art algorithms to capture subjects accurately and reliably. In addition to people, as is often the case with current AI systems dogs and cats can be detected in the subject detection mode.

An L-Mount lens mount allows the camera to be used with a wide variety of interchangeable lenses for mirrorless cameras from Sigma as well as other L-Mount Alliance partners. And if that wasn’t enough, the camera is also launching with nine lenses in matching colours. Essentially this is a renewal of the I series lenses and the nine compact full-frame prime lenses for mirrorless cameras, and the L-Mount versions have been updated to include an aluminium-matching silver option. E-Mount versions are also available and both versions are also available in black.

The BF’s minimalist aesthetic extends to the UI. The default live view screen on the 2.1 million dot display shows only the minimum necessary information and can be changed to display no information at all, while Sigma says the user interface has “a completely new information structure compared to conventional digital cameras. That means in practice that the main shooting-related settings are stored on the live view screen, secondary settings in the optional menu, and management functions and detailed settings in the system menu. The Status Monitor keeps plenty of crucial information off where it's needed.

Users can easily operate the shutter speed, aperture, ISO sensitivity, EV compensation and color mode (it ships pre-loaded with 13 different ones), along with other important shooting-related elements at the touch of a finger. Combined with the auto setting, the functions of the general shooting mode dial are also covered.

Physically it’s small. It measures 5.1 by 2.9 by 1.4 inches (129.5 by 73.7 by 35.6 mm,) and weighs just 13.7 ounces (388 grams). 

Oh, and as for the name, according to an interview with Sigma CEO, Kazuto Yamaki, in Petapixel, 'BF' stands for 'beautiful foolishness' and is a phrase taken from a 120 year old book on Japanese culture called The Book of Tea. Told you it was different.

Pricing and availability

The Sigma BF will launch in April for a suggested retail of $1999. It will ship with a Li-ion Battery Pack BP-81, Metal Body Cap, and be available in both black and silver versions. 

tl;dr

• The Sigma BF is the first camera to feature a true unibody design, carved from a single block of aluminum, taking seven hours to create each unit.
• It features a 35 mm full-frame back-illuminated CMOS sensor with a native ISO range of 100 to 102,400, supporting high-resolution 6K recording at up to 120 fps.
• With a minimalist UI, the live view screen can display essential information or none at all
• The camera is compact and lightweight, measuring 5.1 by 2.9 by 1.4 inches and weighing 13.7 ounces.