Sigma BF Review

Introduction

Respected within the photographic community for its high quality yet affordable lenses for the biggest camera brands around, Sigma’s own cameras appear much less frequently.

The result is that each new iteration becomes a talking point. In the case of its full frame sensor incorporating ‘BF’, there’s more to discuss than usual. 

Noticeably, Sigma’s latest camera eschews most of the buttons, levers and switches we’re used to seeing on an enthusiast-targeted model. It further omits a viewfinder, built-in flash, handgrip, Wi-Fi and more.

Yet by incorporating an L-Mount, this camera is compatible not just with Sigma lenses but also optics from its L-Mount partners Panasonic and Leica. It may look and feel minimalist, but that doesn’t mean there isn’t still plenty of creative scope.

Design and Handling

• Machined from a single aluminium block, with a pared-back control layout
• No eye-level viewfinder, flash, hotshoe or memory card slot
• Touch sensitive main screen and smaller information window make up for paucity of physical controls

The Sigma BF comes in a choice of the silver body seen here for review, or standard black. Lenses to match camera colour are also available. This is vital, as a silver lens on a black body or vice versa can look a little odd.

I was provided with the Sigma AF 35mm f/2 DG lens in silver to test, with a field of view similar to our human eyes and a crystal-clear quality capable of maintaining edge to edge sharpness.

As much as I love the control-festooned, retro-styled Fujifilm X series and OM System cameras, the clean lines of the Sigma BF are a breath of fresh air. Marking a deliberately different approach for the company, this model is as much about form as it is function.

By stripping away the rangefinder-like dials, levers and switches from a full frame mirrorless camera of competitors, a simpler approach is promoted here. Focusing on the essentials of a high-quality sensor and shared lens mount, full attention can be given to the subject, without distraction from never-ending menu screens and physical controls.

That doesn’t mean the Sigma BF jettisons usability. Those who have handled an enthusiast level mirrorless camera or DSLR before will be able to quickly find their way around it and get at the functions they want without too much head scratching.

Not everything needs to come with printed instructions. And, after a few exploratory prods of its pressure-sensitive buttons, operation is sufficiently fluid and intuitive. I didn’t feel in danger of missing a potential shot because I was trying to work out where key settings were.

That said, there are those who will undoubtedly miss what the Sigma BF deliberately omits. That includes an eye-level viewfinder, a built-in flash, and a hotshoe via which to attach an accessory bulb. None of these are present on the device. Even more controversial, there’s not even a memory card slot.

The few controls this camera provides – denoted not with letters but symbols – are almost exclusively on the backplate, with most of available space taken up by an LCD, presented in 3:2 aspect ratio, matching the default image capture setting.

Alternative image ratios including 4:3, 1:1, 6×7, 16:9, 21:9 and ‘A’ Size are presented with black bands top, bottom and sides of the screen to indicate the crop in real time. Sensibly and unsurprisingly, this 3.15-inch, 2.1 million dot resolution screen allows for certain aspects of shooting – such as moving the focus point by tapping on the intended subject where they appear on screen – to be handled via touch.

Key shooting selections are accessible via the main ‘live’ screen by tabbing along to them with a thumb nudge of the four-way control pad/scroll wheel, with secondary functions provided in the menus, if needed. Should even these bare bones on-screen options prove too much, info can be deactivated. 

LCD and menu access aside, you’re left with just the shutter release, the power on/off button, playback button and the scroll dial, via which can also tab left and right, or up and down.

Unusually, a narrow lozenge-shaped window display just above provides quick access to essentials like JPEG or DNG (Raw) capture, single shot or continuous shooting, plus, usefully, reveals battery life remaining. This is displayed as a decreasing percentage, just as on a smartphone or tablet.

From first picking the camera up, I can’t help but notice that another element Sigma omits to maintain the BF’s flat, minimalist profile is a definitive handgrip. 

Yes, there’s a small thumb rest at the back, but at the front there’s just a roughened surface to stop fingers from slipping, its patina mirroring that of the scroll wheel. But more positively, the solid nature of the camera itself, which literally feels like I am holding a lump of metal, ensures that the unit sits firmly.

The design and handling here may be quirky and unconventional, but the effect is that this is a camera I want to spend time with and explore further. Which is surely what any manufacturer wants to achieve with their product.

Features

• 230GB of internal storage 
• 24.6MP effective resolution stills
• Up to 8fps continuous capture

While outwardly the Sigma BF is all about stripping away features to present us with the core essentials, one major point of interest is that, instead of a slot for a removable memory card, it features a generous 230GB of internal storage. 

Back in the earliest days of digital photography, I would pick up cameras that had a very minimal internal cache, allowing a handful of snaps to be taken before the addition of a memory card. But cameras at this level typically don’t offer any internal memory at all; especially one as high as 230GB. Its maker claims this allows for storage of up to 14K JPEGs, 4300 Raw files or 2.5 hours of video. So maybe that memory card isn’t essential after all.

A USB-C port is provided for charging the internal battery and as well as data transfer. There’s no standalone charger or USB cable provided, but a standard smartphone lead and mains plug will suffice, and charging appears quick.

Wi-Fi and Bluetooth aren’t offered here as alternative cable-free means of sharing either. Unsurprisingly, since there’s no hotshoe, there is also no place to plug in an accessory microphone or headphones; something that most cameras in its class and price bracket would ordinarily offer.

While, on the one hand, Sigma claims the ‘BF’ distils photography down to its purest form – a marketing pitch heard from L-Mount partner Leica in the past – it still considers smartphone-like digital filter effects as something worth offering users. But are the 13 different colour modes, including Teal and Orange, Powder Blue and Warm Gold and Rich and Calm essential? Arguably not, though the colour tones in the various modes, mono aside, are mostly subtle and don’t make a massive amount of change to the image.

There’s no wild pop art or punk filters here, for example. The ‘BF’ keeps it classy.

Though the 388g body weight reads as being lightweight on paper, in practice with dimensions of 130.1×72.8×36.8mm and the additional weight of a high-quality lens attached, the camera feels too heavy and bulky to slip into a pocket, particularly with its angular corners and sharp edges.

That’s a shame, as Sigma’s BF otherwise suggests itself as an everyday street and travel photography camera. In fact, it’s one you’ll want to show off in locations as cool and glamorous as the unit itself.

Despite the inherent and deliberate limitations and omissions when it comes to the camera’s feature set, I found myself enjoying using the Sigma BF during the test period, rather than feeling frustrated. A camera that seeks to break the mould encourages some out-of-the-box thinking.

Image Quality

• 20 effective megapixel images as a choice of JPEG or Raw
• Hybrid phase / contrast detection auto focus system
• AI enhanced AF recognition

The more the limitations imposed, the greater the creativity that flows comes to mind for the Sigma BF and the images it’s capable of, when allied with decent glass. 

Though, of course, there’s the option to switch image capture to manual and focus by hand, the Sigma BF’s hybrid phase / contrast detection auto focus system proves as swift and enthusiastic as I would expect of a premium look and feel mirrorless model. 

The camera’s AI enhanced algorithm claims to be able to detect and optimise performance for specific subjects, including dogs and cats, alongside humans, which is now standard stuff, however much externally and operationally the BF wants to buck current trends.

The camera’s AF was quick to recognise the head and eyes of our pet pooch and direct focus to the face accordingly, the background subtly blurred.

Overall, it’s fairly reliable, and I only had to re-direct the focus point with a finger tap when presented with busier scenes or subjects. Or on those occasions where I wanted to direct the eye to something that may not have been immediately slap bang in front of us.

Luckily, when shooting outdoors, the camera’s 3.15-inch main screen can be manually adjusted for brightness. Yes, it occasionally catches reflections, which made me long for an eye level viewfinder, but as everyone is now used to our mobile phone screens for framing and capturing shots these days, relying on a screen exclusively doesn’t feel like a big deal. 

Happily, the 2.1 million dot resolution ensures intended subjects appear not only razor sharp but life-like. Because you need to use the screen all the time however, the percentage displayed for battery life was ticking down more rapidly than I’d have have liked. The official quote is that the camera can capture up to 260 shots from a full charge, which is so-so. It flags up one area for possible improvement if there is a Mark II unit at any stage.

Shooting on days that varied between cloudy and sunny, I typically toggled my ISO settings between ISO100 and ISO400. Alternatively, for those looking to keep shooting as light levels decrease, sensitivity settings can be boosted all the way up to ISO102400 equivalent.

Since the compositional screen is resolutely fixed and doesn’t tilt at all, I found myself crouching, squatting, or even lying down to achieve some shots.

With most digital cameras now featuring swivelling backscreens, it’s been a while since I have had to do that.

As expected from Sigma, the combination of full frame CMOS sensor and 35mm f/2 lens prime lens delivers images of uniform clarity and sharpness, with focus maintained across the frame and into the corners, unless deliberately attempting a shallow depth of field effect.

To be picky, I did occasionally notice some pixel fringing creeping into shots taken on a bright day where the branches of a tree are almost silhouetted against the sky, but such artefacts are only truly visible if zooming right in, and otherwise are not distracting.

Quirky and unconventional, though not obtusely so, my concluding impression is that the Sigma BF is an exciting anomaly in a sea of conformity.

Should you buy it?