The advances in digital video technology over the last decade are nothing short of astounding.
Today’s consumer and professional video cameras have a level of resolution, dynamic range and color fidelity that, just a few short years ago, would have been available only to the upper echelon of Hollywood productions.
One area that has lagged behind development-wise, though, is that of focus, and that has a lot to do with the history of both cinema and the technology. Film still and motion cameras have a shared history, both originating in an era where there was no such thing as auto-anything.
Sony’s new trio of video cameras, the professional-grade PXW-790V and HXR-NX80 and consumer FDR-AX700, bring an unprecedented level of autofocus performance to digital video production, while at the same time providing top-end 4K recording capabilities for uses ranging from broadcast and television production to events to vlogging. Combined with the Sony MCX-500 Switcher, Sony’s trio of new cameras can create a live-broadcast (or record for broadcast) environment complete with pinpoint autofocus, 4K footage, live transitions, picture-in-picture and live titling.
These features make the trio of cameras and the mixer perfect for covering sports, concerts, news and services, and they provide camera operators and producers more versatility and the best video quality in their class.
The Autofocus Dilemma
Both digital still and digital video cameras have a shared history that dates back to the early days of film photography, and while they’ve shared a host of common technological developments, they’ve both become highly specialized according to their unique requirements. Interestingly, the two systems are starting to come back together, thanks to the sophisticated engineering found in mirrorless cameras like the Sony a9 and a7R III.
Still photography has the goal of creating a single image out of a moving scene, a quick distillation of the action in front of it, while cinema and broadcast cameras are designed to capture a rapid stream of images to represent the entirety of that action in fluid motion.
Decades ago, the SLR (Single Lens Reflex) camera became the norm in photography. The mirror (or reflex) allowed photographers to look through a viewfinder and see the subject before them with the same lens used to capture the image. Light enters the lens and bounces to the viewfinder, and when the shutter is pressed, the mirror flips up and allows light to hit the film or digital imaging sensor behind it.
This development also allowed for the advent of autofocus, with camera manufacturers including an autofocus sensor in the pentaprism of the camera. As light enters the camera body not only is that light directed to the viewfinder via the mirror, but it is simultaneously directed to a dedicated autofocus system. This allows SLRs to actively follow a subject and to predict accurate focus for the exposure, focusing the lens accordingly.
When you’re capturing a single still image at a fraction of a second, at speeds no more than a dozen frames-per-second, traditional autofocus is an ally. Try to track critical focus on a cinema camera, though, where you need to ensure that all 30 or more frames are in focus, and suddenly SLR-style autofocus falls flat. There’s just not enough time to bounce light to a sensor between each frame and not enough time for a mirror to flip up and down at moving picture speeds.
Take the inaccuracy of the SLR-style autofocus and combine it with the need to get precise, repeatable focus, and it’s clear why motion pictures and broadcast capture have traditionally been achieved with manual focus.
On a movie set and in broadcast TV, actors are trained to hit a specific spot at specific times so that the camera operator can focus to a precise setting. In sports and other live events—especially with multiple cameras—camera operators shoot with depth-of-field settings that allow them to capture subjects in focus even if they’re moving, and the ability to switch between cameras gives time for refocusing between shots.
Unfortunately, a manual-focus video workflow means that some shots are going to be incredibly difficult to capture, no matter how quickly the videographer can focus manually. A motion picture crew can spend all day doing multiple takes to get an actor’s eye in focus while still shooting a wide aperture to create background defocus, but today’s creatives need to get it right the first time, every time.
Bringing It Back Together
In an exciting twist on the development of still and motion cameras, the two platforms have begun to come together technologically, thanks to advances in mirrorless cameras, like the Sony a9 and a7 series. Where DSLRs use a mirror to bounce light to an autofocus module, a mirrorless camera instead relies on the imaging sensor as its focusing tool.
Early mirrorless still cameras relied on a contrast detection focusing system, which moves a lens back and forth to lock focus. Anyone who has watched a still camera (or most DSLR-based video cameras) “hunt” for focus, racking back and forth until a subject is in focus, has seen contrast detection at work. Contrast detection AF was easy to implement in mirrorless cameras but is too slow and jerky for broadcast or cine-video.
Sony’s sensor-development expertise allowed it to incorporate a more advanced phase detection autofocus system in its still cameras, one that allows for smooth, precise control of a lens to predictively focus on a subject. Sony also developed advanced face-detection and eye-detection focus modes, and accurate tracking, which enables its cameras to lock on and follow even erratically moving subjects. With a combination of phase detection and contrast detection points, cameras like Sony’s a9 and a7R III provide accurate focus in even low-light conditions.
In many ways, a digital video camera is identical to a mirrorless digital still camera, at least when it comes to the internal components. With a sensor, processor and shutter performing the same duties, the differences mostly come down to the operation, recording formats, connections and body design of the video cameras.
Sony’s pioneering engineering in mirrorless still cameras and digital video cameras has enabled it to include this hyper-accurate Hybrid Autofocus in the trio of the PXW-790V, HXR-NX80, and FDR-AX700 cameras. With the most advanced autofocus in their class, these new camcorders allow for tack-sharp focusing in even the most hectic environments.
All three feature a 273-point Hybrid AF System with 84 percent coverage of the frame—this wide-area coverage allows the camcorders to focus as well on the edges of the frame as they do in the center, eliminating the need to focus and recompose a shot to lock onto a moving subject. Focus area can be selected by touching the LCD-screen for instantaneous AF acquisition, while face detection and object tracking keep the cameras locked on as they move across the frame.
All three cameras also provide for fine-tuning of the depth (how much movement a subject makes) and sensitivity (how quickly it jumps to another detected target) for every job. The precision of Sony’s AF system allows these three 4K camcorders to capture video in demanding situations without missing critical focus.
Just as crucial for focus accuracy (especially when shooting handheld), the three camcorders all include Sony’s in-body Optical SteadyShot image stabilization for jitter-free capture, especially helpful when shooting at the long end of the 12x optical zoom (348mm equivalent in full-frame still cameras).
With the ability to nail autofocus and an image stabilization system that reduces unwanted motion, the new camcorders provide a level of accuracy and possibility not previously available in this class. Sports video can track a play from one end of a field to another; wedding shooters can lock onto the face of the bride during a couple’s first dance, event videographers can follow someone moving across a dimly lit stage. It’s now possible to shoot in more places with more accuracy than ever before.
The similarity in the design of all three means that camera operators can quickly grab any model in the family and begin shooting immediately without hunting for a specific control or function. The PXW-Z90V and HXR-NX80 both feature screw-on mounts for carrying handles that accommodate external mics, which feature precision controls for multi-source audio input (including wireless mics).
The OLED Tru-Finder electronic viewfinder found on all three models has 2359K dots plus excellent brightness and saturation, and the LCD screen on each has 1555K dots. Dual media slots allow for simultaneous or relay recording.
Inside, all three have a 1″ stacked sensor, which provides exceptionally high sensitivity capture with low noise and produces broadcast-quality 4K and full HD. They all are capable of capturing 120fps in Slow & Quick Motion modes and can capture Sony S-Log2 and S-Log3. Productions with a need to capture High Dynamic Range can use the built-in Hybrid Log-Gamma encoding for playback on both HDR and non-HDR monitors with no post-processing needed.
The XDPXW-Z90V can record up to 100Mbps in XAVC QFHD and 50Mbps MPEG at 4:2:2 or 4:2:0 with the accessory CBKZ-SLMP. The HXR-NX80 and FDR-AX700 record up to 100Mbps in XAVC S 4K mode.
For broadcast professionals, the ability of the three camcorders to work with the Sony MCX-500 Multi-Camera Live Producer solution opens up a new world of possibilities. This all-in-one control board can work with up to 3G-SDI, HDMI and CVBS connection, which processes video at 1080i. The MCX-500 can output to a video server via its dedicated Ethernet connection and can live stream with direct support for Facebook Live and YouTube Live built-in, or can record to the internal SD slot.
With both physical controls and a touchscreen LCD, the Live Producer can be set up for a variety of workflows. In addition to switching between sources, the MCX-500 provides video effects like transitions and PnP, and supports Chromakey work and can display logos. All the features of the board can be controlled with a single display, making for a compact solution.
Combine the MCX-500 with the Sony accessory RM-30BP remote controller (which connects directly to the MCX-500), and it’s possible to control multiple remote cameras from a single production location, allowing a single operator or small crew to control numerous cameras, mix the video and stream it live.
The road to high-performance video autofocus has been a long one, but Sony’s 273-point Hybrid AF system, combined with the company’s legendary ability to capture professional-level video in a compact camcorder, opens up new possibilities. The PXW-790V, HXR-NX80 and FDR-AX700 give videographers the confidence of knowing that they’re going to be able to focus on their creativity while their camcorders focus on their subjects.
See The Sony 4K Camcorders
For more information on Sony’s trio of 4K camcorders, visit the Alpha Universe website.
To really appreciate the power of the autofocus in Sony’s trio of camcorders, you need to see them in action. These sample videos show of the autofocus prowess of the cameras.
These sample videos offer a look at some of the other features and benefits of working with the Sony PXW-790V, HXR-NX80 and FDR-AX700 camcorders. Note: YouTube’s default playback resolution is lower than 1080p, so be sure to change the Quality setting to get the most accurate footage.
High Frame Rate / S&Q
Video Quality and Resolution