I tested the viral Sigma BF camera, and its radical redesign has me hooked

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ZDNET's key takeaways

Sigma's BF is a $2,200, 35mm full-frame, mirrorless digital camera that radically changes the mode of operation by replacing the gaggle of buttons with an elegant click-wheel.
It's a great first camera but also has tons of pro features
A future upgrade to a higher-resolution 60-megapixel sensor would be a welcome enhancement.

Taking pictures with a digital camera hasn't changed much in thirty years. The electronics have improved, but the basic act of operating a digital camera has remained mostly the same. Cameras are a gaggle of buttons that are a cryptic arrangement to anyone but the initiated.

The real innovation in the picture-taking experience has been the smartphone, which has made picture-taking an always-available tool for documenting everything with relative ease.

There is still an audience, however, for innovation beyond what smartphones offer. Young consumers keep buying digital cameras, and a new generation is always interested to learn more about photography as an art.

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Into the void steps lens and camera maker Sigma Corp., based in Kanagawa, Japan, just outside Tokyo. The company this spring introduced a radical redesign of the digital camera's basic mode of use.

The Sigma BF, as it's called, reduces the mass of buttons to a small set of touch-sensitive controls. All the functions of digital photography are still there to be experimented with and exploited -- shutter speed, lens aperture, or "f-stop," and "ISO," the level of light that can be recovered from a scene -- but they are under your command in a radically simplified user interface.

I've been testing the BF for some weeks now, and I'm smitten with the changes. The hardware's design is beautiful, and the new user interface is very thoughtful. The name "BF" stands for "beautiful foolishness," and you could say this kind of redesign is crazy, but I love it.

A camera for a new age of photographers

Sigma, a sixty-three-year-old company, makes most of its money from lenses for all camera brands. As a result, its cameras have tended to be somewhat experimental, never selling in the same volume as Sony, Canon, or Nikon. That means that the company takes chances. Often, the results are wild and beautiful.

The BF is really meant for a new age of prosumers who want to up their game in photography. At a retail price of $2,199, the price is not insignificant, but it is on the low end for what you'd pay for a very good 35mm digital camera these days. Lenses, which have to be bought separately, run from about $600 for a fixed focal length "prime" lens to $1,300 or more for zoom lenses. The BF uses what's called an "L-mount," which means you're not limited to Sigma's lenses; it's also compatible with lenses from Leica, Panasonic, Samyang, and Sirui.

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The premise of stepping up your game from the smartphone camera is pretty simple, to my mind: You will never, ever, get as good a picture with any smartphone camera as you will with a camera that has a real lens. The lens is the key. The optics are just so superior to the optics on a smartphone.

I tested the BF with a 50mm prime lens from Sigma, the same kind I already use for most of my photography.

No matter what you are photographing, there are immediate benefits to using a real camera versus a smartphone camera.

One benefit is the detail you get. Here's a picture of a butterfly landing on some vegetation in a vivarium. When cropping the image to see the butterfly up close, you'll get a level of detail that is clean rather than the murky detail you get even with a smartphone's optical zoom:

(None of these photos have been edited. They are all straight out of the camera. In some cases, the file size has been compressed to accommodate the publishing system.)

Not only detail but also control of the depth of field via the aperture dial on the lens provides control over the selective blurring of objects, the "bokeh."

Smartphones will give you fake bokeh that is generated in software rather than the actual bending of the light via the lens elements. Rarely will fake bokeh give you a really complex, thrilling effect where both foreground and background elements are selectively blurred, leading to a more sophisticated image, such as this cypress I snapped in New York's Central Park:

And even when fake bokeh works, I don't think you'll achieve the almost holographic, floating beauty you get with a real lens while preserving all the detail of the foreground subject, as with this thistle:

The second advantage is that a real lens will give you more real proportions than a smartphone lens that has a lot of barrel distortion. Like a building architectural shot or this bank vault:

You can get a nice, crisp skyline shot at twilight as the light changes:

A swing to simplicity

Where the BF departs from other cameras is in the simplicity of design and user interface.

The hardware is, very simply, a solid shell milled from a block of aluminum and then filled with electronics. It's a gorgeous manufactured object with a super solid feel. (Sigma cameras always feel super solid, but this is on a new level.)

The BF's body is one of the lightest full-frame mirrorless cameras on the market, at just under a pound, compared to devices such as the Sony a7 IV, which weighs nearly a pound and a half.

For non-camera users, the weight of any real camera is something of a surprise compared to a smartphone such as an Apple iPhone Pro, which weighs half a pound. Holding 15 ounces worth of an unfamiliar object prompted some people to whom I handed the BF to remark, "It's so heavy!"

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The total weight of the camera is the combination of the 15 ounces and the 12 ounces of the 50mm Sigma lens. That kind of heft is typical of full-frame lenses because they have a lot of glass inside them. (And this particular Sigma lens is not very heavy as 50-millimeter lenses go.)

The real adjustment for a novice photographer is getting used to the balance of weight between camera and lens versus carrying a slab of a smartphone with uniform weight distribution.

The camera comes in two finishes, a striking silver color and a deep black. I chose to try the black as I like to use the camera often in discreet settings such as a jazz club, so I wanted something less flashy than the silver.

The sensor is a full-frame, 35mm Sony chip with just under 25 megapixels, less than the 60 megapixels in some 35mm cameras. Despite a lower pixel count, I found the sensor produced rich detail, certainly enough for Instagram pictures and possibly good enough for wall-sized prints depending on the exposure. Sony is a very reliable name for sensors, so it makes sense for Sigma to go with the market leader.

Images are stored in the internal 230-gigabyte flash memory, which I found to be more than enough for my purposes. I usually offloaded the pictures onto my iPad or MacBook after each photo-taking session via USB-C and then cleared the BF's memory.

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On the software side, the radical simplification of the user interface is striking -- it's even something of a revelation.

I've been a user of Sigma cameras for over a decade, my main camera these days being the Sigma fp-L, a 60-megapixel model introduced a couple of years ago. I love that camera, but I would be very happy to see the changes in the BF user interface become standard on Sigma cameras going forward.

The main innovation is removing a lot of shooting information from the LCD screen. Instead of seeing the aperture or shutter speed and other settings constantly on the display, each setting on the BF occupies a separate, tiny LCD -- it's called a "status monitor" though I tend to think of it as simply a "mini-LCD" -- to the right of the main display.

A click wheel just below the mini-LCD, formally called the "dial pad," reminiscent of the first Apple iPod's click wheel, lets you rotate through the values of shutter speed, etc. The changing values are displayed on the mini-LCD as you do so, and you click the center button of the click wheel to select the setting you want.

There's also a touch-sensitive playback button, so you can peek at what you just snapped with a soft touch, and a touch-sensitive menu button, which is a quick way to peek at the camera's settings. And a power button at the bottom of all this, of course.

The effect is that the main display screen is a pristine window into what you're capturing in the real world, while the mini-LCD and the click-wheel are your controls. It's a nice division that elegantly separates the gaze from the adjustments.

The main LCD is a 2.1 megapixel model and is terrifically responsive for things such as selecting the focus area by tapping with your finger, or using pinch and swipe when looking through the photos you've taken.

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If you half-press the shutter button, the display momentarily shows the key settings before you fully commit to the shutter release. If you press on the center button of the click-wheel, or dial pad, extra settings come up for the function that's in focus, such as shutter speed.

Street photography delight

The BF's light weight and simplified user interface made for nice street photography, one of my favorite pastimes.

I tended to carry the camera at my waist in one hand, holding onto the lens, sometimes with the camera body flipped upside-down, with my pinky finger on the shutter button. That way, I achieved a kind of nonchalant pose that did not draw attention to my picture-taking.

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Sometimes, I looked at the LCD to see what I was snapping, but oftentimes, I just took a picture in the general direction to see what chance would produce.

The autofocus function of the BF was super fast, notably faster than the response time of the fp-L, probably because of the BF's lower-megapixel-count sensor. That made for excellent motion capture, such as this basketball game:

One of the BF's shortcomings is having an electronic shutter: Instead of mechanical blades opening and closing, the sensor chip controls in software when the exposure happens. The common knock against an electronic shutter is that it can lead to blurring of fast motion. In the case of the basketball game, in late afternoon daylight, I saw no issue.

Another potential drawback is that indoors, in artificial light, the electronic shutter can produce dark bands across the image if the shutter speed is too fast. That can require you to take the picture at a slower shutter speed. In practice, I found it not to be much of a problem.

Improved electronics

In addition to autofocus speed, Sigma has done a very good job with the BF's low-light support, which was already quite good on the fp-L.

One of my favorite low-light picture tests is a diorama in the North American mammals hall of the American Museum of Natural History in Manhattan. This is one of the darkest exhibits in the museum, and it's challenging to photograph if you don't have the camera resting on a tripod to allow for a long exposure.

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Two taxidermy wolves run on a painted landscape of the Michigan countryside. To the naked eye, the diorama is very, very dark because it is meant to suggest nighttime on the prairie. Here's what it typically looks like, taken with minimal low-light support by the BF:

Most museum visitors who view the diorama turn on their smartphone camera's flash to take a souvenir shot. But, to my mind, flooding the scene with flash spoils the effect.

Instead, I cranked up the BF to its highest ISO setting, 102,400 -- fairly high up there for any digital camera. The result is that the wolves emerge in beautiful detail from the darkness -- not as sharp or clean as if the scene were well-lighted, but that's the point:

In practice, the BF does a very nice job in darkly lit spaces where you might actually want a picture, such as a jazz club.

When set on a tripod with professional lighting and a backdrop, the BF is also excellent for formal portraits, far better than what you'll get using a smartphone camera for your headshots.

Sigma BF, 50mm, f/2.5, 1/640s, ISO 3200

Tiernan Ray/ZDNET

Even without using a macro lens, the 50mm will allow you to get pretty good closeup shots of something like your favorite toy, from a minimum distance of 18 inches, which you can then crop and still have lots of vivid detail.

Of course, you could also add a macro lens to the BF and get even closer.

A gentle introduction to pro features

Sigma has simplified some of the functions for newbies so that the same technical effects are present but in a more inviting fashion. For example, on the Sigma fp-L, a separate button is for "tone control" that lets you adjust the light across the scene by degrees for shadows and highlights to make a scene have more or less contrast.

On the BF, there's no button for tone control, but when selecting colors with the click-wheel, you can bump up or down values of "highlight," "shadow," and "fade," to alter the degrees of lights and darks. That works in both still images and videos.

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There's also an option called "look effect," where you can dial up or down how vivid or how flat a given color filter is, which is a nice, obvious way to understand making your pictures or videos more striking or more sedate.

In practice, the BF does a great job with tone and exposure on automatic. A street scene at sunset, for example, nicely balances the vivid highlights of the sky with the street detail without blown highlights or detail lost in the shadows.

When you review photos, the main LCD display gives you all the information on the tone adjustments you made, which is helpful for determining what works and what doesn't.

Some things that are typically buried in sub-menus on digital cameras are brought forward in the BF's UI.

So, for example, when filming a movie, you have the option to turn on "constant AF," which does a better job of grabbing hold of a new subject entering the frame. That is now an option from the click-wheel rather than being buried as a sub-menu option.

Of course, there are trade-offs to simplicity. Other functions that were accessed directly via dedicated buttons on digital cameras become things you have to hunt for.

For example, auto-exposure lock forces the camera to keep the amount of light in the scene the same as you move it, rather than altering the exposure. This allows you to find the right balance of light and dark and hold onto it while you shift your focus.

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On the fp-L, auto-exposure lock has its own button. In the BF, you have to move the click wheel to the exposure section of the menus and then turn on auto-exposure lock by tapping on the icon. This extra step is fine if you don't use auto-exposure lock much.

Another example is a feature of most digital cameras called fill light, the ability to lighten up dark parts of a picture. On most cameras, you have an option to turn on the fill light while you're taking pictures. On the BF, fill light is something you adjust after the fact by editing the DNG, "digital negative," or "RAW," image in the camera.

Sigma's suggestion overall is to use color and filter adjustments to achieve a similar effect to fill light. In other words, the user interface consolidates traditional operations such as fill light and auto-exposure lock into a simpler set of choices that can be more centrally manipulated.

And some things are just different. On the fp-L, and most cameras, when recording a video, you can take a still image as you're recording. On the BF, if you want a still image as well, you do it when replaying the video, by selecting "save as JPEG."

How it performs with video

Speaking of video, I found the results were very satisfying. You can take 6K video (6,016 x 3,384) that looks great even without electronic stabilization turned on.

I took this shot of a woman having her personal photo shoot in front of the Plaza Hotel. Although it's jerky and not cinematic, it was a wonderful spontaneous moment in great quality:

When you turn on the electronic stabilization feature, video is reduced from 6K to "ultra-high-def" (3,840 x 2,160) because the camera needs to crop each frame to line up frames and make the shakiness disappear.

In a low-light setting, such as this video at Small's jazz club in Greenwich Village, I thought it produced a wonderful-looking film without a tripod.

Here's where we see an example of the click-wheel at its best. I had the fun of rotating through the different color filters to change up the color from moment to moment while filming, something I would never do when color choices are a single button.

Although my use of the feature is rather gimmicky here, I can see all kinds of possibilities with the click wheel, enabling new ways of controlling the camera during filming.

Like all cameras, the sound you record with the built-in microphone video is never as good as if you had a dedicated mic attached, especially for something like music. But I thought the result here was very good in a space with challenging acoustics.

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Even in low light, using the camera hand-held, you can get a nice video like this one taken in a darkened tango hall. In a dark place like a dance hall, with swaying bodies moving to and fro, with the camera in your hand and no stabilization turned on, it can be challenging to capture motion in a way that's satisfying. I love what the BF did with the color and the lights in this scene while managing to shift autofocus from one couple to the next:

Battery life

Battery life was fine for my purposes. I got as much as six hours of shooting on a single charge, including intermittent shooting and periods of intense activity. That meant in some cases over 500 exposures in DNG+JPEG format. That's better than the official specification by Sigma for approximately 260 images on a charge. Of course, your results may vary.

In my experience, plugging the BF into an iPad via USB-C for forty minutes will charge the camera from zero back to a third of its battery life. You can also bring along a spare battery and swap it in via the latched compartment on the bottom of the BF.

ZDNET's buying advice

The complaints I've seen about the Sigma BF from seasoned photographers seem to be mostly about the reduction of controls to the click wheel and the mini-LCD. Consolidating controls in that way, they argue, robs the pro photographer of their muscle memory. Some pros also wish the touch screen did more to control the functions rather than just serving as a very good display.

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In essence, pros have a hard time adjusting to a radically simplified UI. It's a fair point of view, but this is something of a Steve Jobs moment. You have to break a few eggs to make an omelette, and you may have to break habits to reinvent how photography is done.

I think the BF is a terrific option for a beginning photographer or even an experienced pro. The touch-screen display is intuitive in a smartphone age, the electronics are just as fast as you'd expect based on smartphone picture-taking, and the output is very Instagram-worthy.

And your envious friends will immediately want to know, What is that wild-looking camera you've got?

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