What is is?

The much-leaked Sony FX3 has finally been publicly announced. As expected, it’s an E-mount full-frame video camera that sits at the bottom of Sony’s ‘Cinema Line’ and bridges the gap between the portability of the a7S III and the capability of the FX6.

To a large extent, it can be seen as an a7S III in a more filmmaker-friendly form. So let’s have a look at what that really means.


Like the FX6, Sony says the FX3 has a 10.2MP BSI-CMOS sensor. Which is true if you only shoot video with it. However, the FX3 can also shoot 3:2 aspect ratio stills using a taller region of the sensor because, as you might have guessed, it’s actually the same 12MP sensor used in the a7S III. It also has a mechanical focal plane shutter if you do want to shoot stills.

The use of the same sensor no bad thing, given it has very good readout rates (essential for a video camera) and excellent performance in terms of noise and dynamic range. The FX3 uses the same Bionz XR processors as the a7S III and gets its much improved menus, too. The only major difference is that the on-screen display of AF tracking match the rest of the Cinema Line cameras, rather than those of the Alpha cameras (it’s only a subtle difference).

The FX3 also comes with the S-Cinetone color response, which the a7S III currently lacks, in addition to the S-Log and HLG options they both share. But all the signs point to this difference only lasting until the next a7S III firmware update.


The big differences between the a7S III and the FX3 are in the body design. The FX3 looks more like a beefed-up a6x00 series camera, rather than the SLR-shaped a7S III. But look round the back and you’ll see the FX3 doesn’t have a viewfinder, for reasons that will become clearer on the next slide.

But the most significant difference between the two cameras is, perhaps, what you’ll see as you turn the camera round: the ventilation ducts that carry heat away from the back of the camera, thanks to a fan built in behind the tilt-out touchscreen. This fan cooling extends the camera’s recording duration compared with the a7S III, but also provides a greater degree of dependability/predictability that’s essential for expensive shoots. The fan unit sits outside the camera’s weather-sealed body, to avoid providing a path for dust or moisture ingress.

The other fundamental distinction between the camera bodies you need to dig a little deeper. Rather than simply being harder metal inserts embedded in the camera’s magnesium alloy shell, the five 1/4-20 UNC threaded mounting points on the body of the camera are all part of a stainless steel under-structure that wraps around the core of the camera. This allows it to be rigged up with all manner of accessories without the need for an external cage.

The other distinction is that the FX3 has front and rear tally lamps, so it’s more obvious when the camera is recording.


The FX3’s controls are also different from those of the a7S III or, at least, differently positioned. Whereas the a7S III is primarily designed to be shot held up to your eye, the FX3 has had its control points rejigged to allow easier control when shooting in something more like a waist-level stance.

The camera’s joystick is on its top plate, as is a larger, more easily reached [REC] button. Many of the rest of the camera’s controls resemble those of the a7S III, with dials at the front and back of the top plate, as well as one placed vertically on the back of the camera. These control iris (aperture), ISO and shutter speed, respectively. But, like the FX6, each has a corresponding button that cycles between the dial between being active, being locked and that parameter being controlled automatically. According to Sony there’s logic to the arrangement of some of these buttons to make things easy for a solo shooter. ISO and iris together on top, since they are settings a camera operator changes frequently, and shutter relegated to the back since it’s not changed very often.

The final distinction is that the rocker switch on the top of the FX3 is used to control power-zoom lenses: a function the a7S III doesn’t have a physical control for.

XLR handle

In keeping with the FX3’s low-level/underslung shooting design is the included screw-on handle, allowing the camera to be held steadily during a wider range of movements.

Significantly, the handle includes a built-in XLR audio adapter. This is very similar in spec to the XLR-K3M adapter that can be fitted to the hotshoe/multi-interface shoe of existing Sony cameras, but the multi-interface connection is at the base of the handle.

Like the XLR-K3M, the XLR handle includes a pair of XLR/6.3mm (1/4″) TRS connectors with separate volume controls for each. There’s also a 3.5mm stereo connector, in addition to the one already on the camera’s body. Any audio delivered through the XLR handle is digitized and sent to the camera via the hotshoe. When used together, the XLRs and 3.5mm jack support 4-channel audio recording.

The handle also adds three further 1/4-20 UNC connectors.

When considering the cost of the FX3, relative to the a7S III, it’s worth considering that adding a XLR-K3M adaptor to the ‘S III costs around $600 (though you also get a shotgun mic for that money, not included with the FX3).

Video capabilities

At its core, the FX3’s video capabilities are an exact match for those of the a7S III. It can shoot UHD 4K at up to 60p from the full 4.2K pixel width of its sensor. It can also shoot UHD 4K at up to 120p from the native 3840 x 2160 region (which imposes a slight crop).

All these options can be captured as 10-bit 4:2:2 video, with a choice of the XAVC HS (H.265), XAVC S (H.264) or XAVC S-I (All-I H.264). As with the a7S III, most of these combinations can be written to comparatively modest V60 SD cards, with only V90 rated cards able to shoot almost everything and only All-I 120p, shot via the cameras quick and slow mode, demanding a CFexpress card.

XAVC HS footage can be captured as either 4:2:2 or 4:2:0 10-bit files, whereas XAVC S gives a less-efficient 10-bit 4:2:2 option or 8-bit 4:2:0 capture. All-I capture is always 10-bit 4:2:2.

In addition to the 4K capabilities, the FX3 can shoot 1080p at up to 120p, either from the full sensor region or a Super35/APS-C crop. 1080 footage is captured as either XAVC S or XAVC S-I.

Like the a7S III, the FX3 can output 16-bit Raw video data over its full-size HDMI port, if you have an external recorder that can encode it as something useful.

The key area where the claims about the camera diverge is, of course, endurance and dependability, with the FX3’s fan providing extended capture times.


The FX3’s stabilization is much like that of the a7S III (which won’t come as a surprise if you’ve followed the ‘a7S III in a different body’ narrative this far).

At its most basic, you can use the camera’s in-body stabilization which can help compensate for a little of the jitter of handheld shooting. There’s also an Active SteadyShot mode. This crops in the image a little, using a 4K chunk that can be moved around within the bounds of the 4.2K sensor to provide additional correction. This is only possible at up to 60p, because the 120p mode is only available using the central 4K area, so it can’t crop-in further to provide additional stabilization without using a sub-4K region.

The camera also writes data from its gyro sensors as metadata to the file, this lets you apply digital correction in post, using Sony’s Catalyst Browse or Catalyst Prepare software, which lets you decide the balance between the extent of the crop and the degree of stabilization applied.

What’s missing

In pointing out how many of the FX3’s features are shared with the a7S III, it’s also worth pointing out that they also share many of the same omissions.

Given its ability to shoot 24, 30 and 60p footage without changing the angle of view, and even 120p without a significant change in the appearance of the footage, it’s a real disappointment that the FX3 doesn’t let you control exposure time in terms of shutter angle. This is hugely useful because it means you can change frame rate without having to change exposure time; instead you just need to adjust iris or ISO.

The other obviously lacking feature is the ability to shoot DCI 4K. The sensor has enough pixels to capture the wider 1.89:1 format, despite this being a feature offered by the FX6, with which is also shares many of its internals.

The final oversight is the lack of waveform display, a popular method in the video world for setting and checking exposure. Most external displays and recorders can generate a waveform display, but adding one to this camera immediately chips away at the portability for which it’s been designed.

Of course it would also be nice to have built-in ND filters, but there’s no room in a body this small, and it’s one of the things that helps distinguish the FX3 from the larger FX6.

So what’s the big deal?

It’s easy to look at the FX3 and wonder why it exists, given how similar it is to the a7S III. From a pure hardware perspective, you lose a viewfinder and gain both a fan and an XLR adapter box in a camera with a list price that’s $400 higher.

But for productions that need to be able to depend completely on their camera being able to keep shooting, the difference that fan makes is significant. I wrote in the a7S III review that it made a credible competitor to Panasonic’s S1H, but the FX3 is an even close match for its compact-but-dependable feature set.

If anything, the FX3 invites the opposite question: who is the a7S III for, once this camera exists? Coming just seven months after its SLR-shaped sibling, we suspect there’ll be a number of independent videographers and small production houses who’ve bought a7S IIIs, wondering why Sony couldn’t have just offered them this, instead.

It seems reasonable that some people can forego the FX6’s button-for-everything layout, its use of larger batteries and the convenience of its built-in ND filters, in return for compactness, but how many a7S III users wouldn’t rather have the FX3’s more video-centric ergonomics and added reliability?

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