DJI Focus Pro reviewed: unleashing cinematographic firepower

The DJI Focus Pro is the company’s first independent Automated Manual Focus lens control system and uses LiDAR technology and modular motors to produce a highly impressive bit of kit.

One of the tricky things about the world’s infatuation with old still photo lenses is keeping them in focus, especially given our interest in enormous sensors (or even more enormous than that). DJI’s Focus Pro system addresses that issue from a few different perspectives – and that means it can do a lot of things in a lot of ways.

The four core devices include up to three motors, the laser rangefinder, the hand controller, and a grip controller designed to clamp on the side of a handheld camera. In the photographs accompanying this article, the system is shown with Fujifilm’s X-S20 camera, creating a rig light enough to make the Fujinon MK18-55mm T2.9 zoom practical on the new DJI RS4 Pro gimbal. It ended up a little nose heavy, as the dovetail won’t slide back quite far enough. Still, the gimbal had enough power to compensate, at some sacrifice to battery life. Of course, with the lighter XF 16-80mm lens, or with most other stills glass, things were straightforward, though the Focus system works mainly with mechanical lenses.

Shown without cables for clarity, we discover that if we want focus, iris and zoom all at once, one of the motors needs to be on the other side

Conventional plus LiDAR

At first glance, the hardware looks pretty conventional: the motors are normal, the hand controller approximates devices focus pullers have been using for decades, and the grip essentially reformulates that with a fingertip control wheel to be clamped on the side of a handheld camera rig. The controllers will both operate the motors conventionally, if that’s what we want, with interchangeable dry-wipe marking surfaces for the hand controller.

What makes all this interesting is the company’s laser ranging technology, now improved with longer reach and more resolution. DJI suggests a twenty-metre range, inevitably depending on what else is in front of the rangefinder. It likely won’t have the legs for ultra-long-lens shots of distant objects that a phase-detect system like Canon’s could handle, although that isn’t a feature which can be bolted onto any camera as DJI’s Focus Pro can. We discovered DJI’s lidar technology in the context of the company’s wireless monitoring system last year, and enjoyed its ability to produce a top-down view of the scene on DJI’s companion monitor. Focus pullers of decades past would have eaten their tape measures for something like this.

DJI Focus Pro on the Fujinon MK18-55mm. It's a big lens for the RS4 Pro gimbal, but it works

The system references the rangefinder to implement either full auto focus, with feature tracking using the rangefinder’s onboard wide-field camera, or in a hybrid focus mode which combines some of the benefits of both manual and automatic systems. It’s a novel approach to keeping things sharp which works with either controller, so it will find use on both fast-moving documentaries and more considered single-camera drama.

We can also rely on the touchscreen on the gimbal grip itself. That’s a slightly fiddly way to do it, but given there’s automatic feature tracking it’s surprisingly effective. A full-scale setup with three motors, rangefinder, and grip becomes a significant combination of equipment and cables, although that’s more or less inevitable given the level of modularity. All of this does rely on a lens with proper mechanical focus: the Fujinon 18-55 (and most classic stills lenses) fulfil that requirement, while the 16-80 does not. The system will still operate as a conventional follow focus on any lens, though we can’t take focus marks and the automatic features won’t work.

DJI Focus Pro hand controller. It runs on a single battery of Sony's NP-F550 format, which is not supplied

Enticing results

On a mechanical lens, results are enticing. The image tracking isn’t perfect – it never is – but the system is is good at focussing on the sort of slow-moving subjects which are a real nuisance for manual focus pulls. Ergonomically it’s about as good as it can be for a single operator, and the hybrid mode offers a lot of assistance. In a more conventional drama setup where there’s a dedicated focus puller, that assistance is still an option, although the hand controller could possibly do with some way of warning the focus puller that a mark is approaching. Right now, the motorised handwheel hits a detectable, motorised end stop at the mark, but there’s only two marks and no warning that one is nearby. Perhaps something for a firmware update.

Various kits are available, though to give an idea of price, the hand unit is something like a seventh the price of – say – the nearest Preston equivalent, or alternatively it’s quite a bit more than things Tilta offer. Neither of those options though has anything even remotely approaching the feature set of the DJI system. The grip is about half as much, and the motors around $150 each, though everything’s a better deal bought as a kit. The hand unit might feel hollow to people accustomed to machined alloy, though it’s a lot lighter than it otherwise might be and more or less everything else is metal.

As so often, the motors are actually a little over-powerful for some lenses, even at minimum torque

The Fujinon XF18-55mm isn’t a large or hard-to-operate lens, though it put the motor absolutely as far as possible from the camera. That gave the motor leverage on the supplied rod, and even with everything tightened down it was possible for the gears to skip during calibration when the system needs to find the end stops. A more conventional dual-rod system would offer a bit more rigidity, and the 18-55 is a torture test for a handheld gimbal to begin with. Given a conventional stills lens there’s more than enough rigidity to keep things lined up and everything works nicely.

DJI Focus Pro: The verdict

It’s hard not to be enthusiastic about such a densely packed assemblage of cinematographic firepower. A more traditional production might use up to three people to carry, operate and pull focus, to get the absolute best out of it, but that’s often the case with gear that puts a lot of features into a small package. Kits including a motor, grip and lidar (not the RS4 gimbal) start at around $999, which seems like a pretty attractive deal for a focus system with unusual features which will remain relevant to potential future gear.

The only issue is that it’s going to redouble the efforts of the world’s indie filmmakers to empty eBay of old stills glass, which no longer have to sacrifice all the conveniences of autofocus.