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Joining Forces for 4K: Combine Sony’s NEX-FS700 and AXS-R5 for a 4K Cinematography System

I reviewed the Sony NEX-FS700 in the November 2012 issue of Digital Video and at that time wondered about Sony’s “4K ready” claims. Sony’s 4K strategy for the FS700 camera became clearer after the announcement of the PMW-F5 and F55 cameras, which included details about the dockable AXS-R5 4K and 2K recorder. Somehow the FS700 would be upgradable to output 2K and 4K video from its 3G-SDI spigot to the external recorder.

Greater-than-HD resolutions are now possible from the FS700 through a combination of external hardware and a firmware upgrade.

The $400 firmware upgrade requires sending your FS700 to a Sony service center in New Jersey or Los Angeles. The upgrade itself enables linear 12-bit 2K and 4K output and adds the S-Log2 gamma as found in the F5 and F55. Other benefits of the upgrade include increasing the maximum camera ISO from 20,000 to 64,000 and adding HyperGamma (800% Rec. 709) curves.

The $400 upgrade fee is waived with the purchase of the HXR-IFR5 interface ($2,500 MSRP), which interconnects the FS700 to the AXS-R5 raw recorder.

NEX-FS700 camera

The HXR-IFR5 unit receives the uncompressed bit stream carrying raw sensor data, metadata, timecode and start/stop commands from the FS700 via 3G-SDI. It controls 4K/2K recording and playback, and uses a comprehensive file naming convention including camera ID, reel number, shot number, date and a unique two-character user-generated ID.

The HXR-IFR5 also coordinates simultaneous recording for seamless online/offline capture: you can simultaneously record 4K on the AXS-R5 while recording HD on the NEX-FS700, with identical start frame, stop frame and timecode. When attached to the HXR-IFR5, the AXS-R5 can act as a standalone playback unit for confidence monitoring and review through the onboard HD-SDI 422 output.

The AXS-R5 is the same recorder that mates with the F5 and F55, creating a definite economy for users of these CineAlta cameras. It’s plausible that one might use an F5 or F55 as primary camera on a shoot and an FS700 with HXR-IFR5 interface as B-camera, exchanging the AXS-R5 recorder as needed between them.

When combined, the HXR-IFR5 and AXS-R5 form a raw recording system that attaches to the NEX-FS700 via SDI cable.

The FS700 kit works a little differently than the F5/55, where communication with the R5 is integral to the system. The difference here is that the FS700 does not sense the presence of the external recorder. It will send out an SDI start/stop signal and output the 2K/4K signal but doesn’t know whether the recorder is actually attached. It makes for a certain convenience if you’re not using an internal card because you can trigger recording from the IFR5 interface unit manually if you like.

The FS700 is known for its high-speed shooting capabilities, but such footage can be recorded only in bursts—and in the case of the highest frame rates (480 and 960 fps), at reduced resolution. (The resolution of 120 and 240 fps video is full 1920 x 1080.) When configured with the AXS-R5 external recorder, however, the FS700 will record 120 fps or 240 fps at 2K resolution for an unlimited duration, while at 4K it can record four-second bursts at 120 fps.

Note that these frame rates are available only through the external raw recorder. If recording simultaneously to SD cards in AVCHD, frame rate will be whatever was set in camera (up to 2K raw in full resolution, with no windowing of the image sensor).

Ergonomics Can Be A Bit Tricky

Whether shoulder- or tripod-mounted, the accessorized FS700 makes for a long rig likened by some to a rocket-propelled grenade launcher.

To the left is a photo of the FS700, AXS-R5 recorder and accessories as configured for my test. Thanks to our friends at Zacuto for providing a rig consisting of a mini baseplate with 12” rods, recorder assembly rod mount, shoulder pad, angled handle with ARRI-standard rosette, and Z-Finder EVF.

Whether shoulder- or tripod-mounted, the accessorized FS700 makes for a long rig likened by some to a rocket-propelled grenade launcher. But I must say that on the shoulder, this rig (using the stock Sony lens, which I honestly would not recommend for serious shooting) is nicely balanced.

The camera configuration I tested, with the stock E-mount zoom lens, proved quite a challenge to balance on my Sachtler Video 15 fluid head. That situation would be remedied with a heavier piece of glass on the front. E-mount adapters are available for any number of mounts.

The Footage

Sony Creative Software RAW Viewer

The AXS-R5 records raw MXF files. Note that the MXF file structure differs between implementations. Raw files from the FS700 are not compatible with Blackmagic DaVinci Resolve 9, but Blackmagic plans to add support in Resolve 10. Adobe Premiere Pro CC will import the raw files with the Sony-supplied free plug-in. Assimilate Scratch can read the MXF files natively.

I tested opening, one-light correcting and export using Scratch Lab, Assimilate’s production dailies application. Results were perfect.

In the absence of a direct Resolve workflow, I opened the MXF files in Sony’s RAW Viewer and did a one-light correction. These files are recorded in linear raw. For grading purposes, I wanted to bake S-Log2 into my output files. RAW Viewer would then let me export DPX, OpenEXR, trimmed raw or SR Lite files. To work with Resolve 9, I chose to export DPX files, which imported perfectly into Resolve 9.1.5.

The simplest workflow currently available is to use Sony’s free RAW Viewer. RAW Viewer is an underappreciated tool from Sony Creative Software that enables not just the export features I mentioned above but also extensive exposure and color tools and an optimized debayer engine.

Pushing this FS700-shot 4K footage two full stops to an ISO equivalent of 3200 produces a well exposed image with virtually no grain.

The true strength of raw recording can be seen in this example from Sony’s RAW Viewer. The footage is from a cooking demo video, shot in 4K and underexposed at the native 800 ISO of the camera. Pushing the image two full stops to an ISO equivalent of 3200 produces a well exposed image with virtually no grain.

Note that the footage is linear raw. When opened in Sony’s RAW Viewer, Adobe Premiere or Assimilate Scratch, it has a Rec. 709 look. The first thing to do is to change the settings to S-Gamut/S-Log2 and grade that as log footage in order to bring out the maximum dynamic range afforded by the raw footage. Those DPX files I exported and brought into Resolve 9.1.5 then no longer have the control that one would have with raw files brought natively into Resolve, but they act as S-Log2 footage. Thus, apply a LUT and/or grade as you would any S-Log2 footage.


I stand by my earlier review, in which I said the FS700 camera itself is a remarkable value with significant applications in documentary, cinema or high-production-value television. It can work independently or cut nicely with the rest of the Sony CineAlta line. Add the HXR-IFR5 and AXS-R5 and you have a full 2K/4K workflow that offers a few things that the F5 and F55 do not offer at the moment—namely exposure tools (histogram), 2K recording and HFR recording in 2K/4K resolutions. The ability to use the AXS-R5 recorder on both the FS700 and F5/F55 cameras is a compelling argument for committing to the Sony ecosystem.  

Product: Sony NEX-FS700 with HXR-IFR5 adapter and AXS-R5 external recorder

Pros: All the benefits of the FS700 camera plus 2K and 4K recording. Frame rates of 120/240 fps continuous in 2K, 120 fps burst in 4K. Simultaneous proxy recording with same file name to SD cards. Compatible with dailies and grading applications. All of the strengths of raw recording.
Cons: The full rig is very long. 2K recording not as crisp as 4K. Still weak internal codec within the camera.
Bottom Line: The best entry-level 2K/4K solution on the market. Under $20K buys a production-quality system that fits well within Sony’s line of 4K devices.
MSRP: NEX-FS700 $9,137.33 with lens, HXR-IFR5 $2,500, AXS-R5 $6,300