Hands-on review: Viofo A139 Pro 2CH dual dash cam
Image credit: Viofo
Viofo updates its dash cam range with Pro specs.
We looked at this dash cam's predecessor, the Viofo A139 3CH, back in 2021 (where does the time etc). For that review, we had the 3CH triple-camera setup (front, interior, rear). This time, we've been testing the Pro 2CH IR system (front, interior).
If you're slightly confused about these somewhat cryptic product names, join the club. Picking the perfect Viofo for your needs is more perplexing than it perhaps needs to be. The Viofo A139 Pro Series has four different configurations, with more or fewer cameras, depending on the name: Viofo A139 Pro 2CH (front, rear); Viofo A139 Pro 2CH IR (front, interior); Viofo A139 Pro 3CH (front, interior, rear) and - yes! - the Viofo A139 Pro 1CH (front).
At least all the front-facing cameras are true 4K UHD HDR, so whichever system you plump for, you're going to get excellent footage. The main cam shoots 4K at 3,840 x 2,160P, which translates to a 16:9 letterboxed aspect ratio. Given the crisp, rich colours of the 4K footage, it's undeniably the best-quality option, but you do lose some 'height' to the footage. Downscaling the camera's resolution could give you more vertical space, although a dash cam is mostly concerned with capturing the horizontal worldview unfolding before it. That is its raison d'être, after all. The viewing angle of the front cam is a wide 140 degrees. There are cams that go wider, but 140 degrees will take in most of what the driver sees. The rear and interior cams each shoot at 1,920 x 1,080P, with a viewing angle of an even wider 170 degrees.
A three-camera system is obviously going to give you the best coverage, keeping an eye on pretty much the entire world that surrounds your vehicle at any given second. However, there are other considerations to take into account, such as the more elaborate set-up and wiring requirements for three cameras, as well as potential heat issues when running three HD cams simultaneously.
In fact, the 3CH version is intentionally limited to 24fps for this latter reason. It's a balancing act: typically, the more channels in a dash cam setup, the lower the bitrate in order to keep the full system ticking along nicely. If you want the maximum fps and bit-rate for your 4K footage, you may prefer a single or dual-cam system. Any of the resolutions and frame rates for the cams can also be easily adjusted, on the fly, to suit personal preference, need or conditions.
As with the Viofo A139 3CH, the Viofo A139 Pro 2CH IR (just the Pro 2CH from here on in) is not cheap, but it is very well equipped to capture some of the best dash cam footage you can get today, as well as a few additional features that other cams simply don't have.
First and foremost, the biggest boost that the Pro range has been given is in its use of Sony's new Starvis 2 IMX678 1/1.8 inch image sensor. The Starvis was already a stellar sensor for use in dash cams - and is used to good effect in the Miofive Dash Cam Dual and the VanTrue S2, for example - but the second generation is even better. It now captures a wider dynamic range in a single exposure, meaning much less noise and motion blur during day or night recording.
There are good comparison examples of images captured with Starvis vs. Starvis 2 on the Viofo website. The new sensor is, as you'd expect, better in every respect. Its inclusion in the A139 Pro range makes them the first real 4K dash cams supporting up to three-channel recording.
The Pro cameras have also been optimised for dark journeys, with Night Vision 2.0. The HDR processing has been improved to reveal more fine detail and better contrast between light and dark areas, meaning clearer number plates, car model detail, road signs and people.
The front 4K camera lens can also be rotated nearly 300°, enabling the driver to position the cam where it suits them best. Depending on where you place it, it can either be looking at the road ahead in a traditional orientation or rotated to look back into the vehicle - either/or, according to the needs of the moment.
The shape and dimensions of the main Pro 2CH cam are the same as the previous model, with its chunky wedge design, and a smaller cylindrical shape for the interior (and/or rear) cam. The main cam is not the most attractive of dash cams - rival firms have come up with subjectively better takes on the concept - but the A139 is smaller than it appears in photos so it doesn't dominate or distract your eyeline.
Installation has also been refined for this Pro range, using slimmer coaxial cables and miniature connectors, approximately half the thickness of previous materials and components. This makes running the cables around your vehicle neater and easier to hide. Viofo also claims these new cables also allow for better electromagnetic interference reduction, although we didn't measure this.
The 5GHz Wi-Fi connection module has also been upgraded, to provide Wi-Fi data transfer four times as fast as the previous model. It's certainly very slick and the video previews, downloading and sharing we tested all seemed to happen instantaneously and in a seamless manner. As with other dash cams, there is an app for the Viofo, which is where anyone can connect to watch a live stream from the cams. It's also where videos are captured, saved and stored, with the GPS log detailing location, speed and time data for the vehicle.
We like the fact that the yellow 'warning triangle' button in the centre of the main cam's body is slightly larger than the other buttons, making it easy to hit with one finger. This is the button that locks an important video, so it doesn't get erased on the next pass.
The Pro 2CH also has plenty of hardware I/O for various connectables, including the SD card slot (support for up to 256Gb) and a jack for an optional external microphone so the driver can capture conversations inside and outside the vehicle. There's also an optional Bluetooth Remote Control, which is effectively a one-button capture/protect command, and can be placed much closer to the driver for greater convenience and safety.
A circular polarising lens (CPL) sunlight filter can be attached to the front-facing camera to reduce reflections and the glare from glass and shiny road surfaces. Just like a daylight filter for your big-body SLR/DSLR camera, the CPL filter can bring significant improvements in image clarity and contrast. In combination with the Pro's superior HDR processing, the resulting footage is almost always better.
Like other dash cams, the Pro 2CH can also be hardwired (there's an optional kit for that) to facilitate 24/7 parking monitoring and auto-event detection (bumps in the night), plus it supports time-lapse capture and a low bitrate mode if all that 4K action is eating through your SD card too quickly. Voice notifications emanating from the main cam are another customisable feature, with multiple languages supported.
The Pro 2CH is a great two-camera system, suitable to fit inside any vehicle. Any of the A139 Pro series setups will deliver terrific results, as they're all identically equipped. The main cam might not look the best, in terms of industrial styling, but at least the R&D money has been spent in all the right places. As we said earlier, it's not a cheap dash cam system, but it's also not overpriced for the impressive results of which it is more than capable. If you've got the cash, go Pro. Come for the Starvis 2 sensor; stay for the true 4K UHD footage.
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