This summer saw the beginning of 4K live sports production, with both Wimbledon and The Confederations Cup experimenting with the new resolution. Adrian Pennington takes a look at the latest options for 4K shooting.
hile live-to-air Ultra-HD broadcasts are not likely to begin before 4K VOD delivery, pay-TV operators are testing elements of the live 4K production chain, and in particular the cameras and lens options.
One of the problems with the current crop of 4K cameras is that they almost all have large single 35mm sensors that have the shallow depth of field which looks good for drama, but not for most sports, where greater depth of field is much more useful.
Early tests involved the picture-stitching of dual 4K cameras for operators to reframe and rescale for pan and scan HD extraction. Single 4K cameras (For A FT-One or F65 for example) have been used to pick out detail in replay analysis, again scaled down to HD on transmission. The feeling is that even when compressed to HD more of the additional 4K information is apparent in the result.
There are as yet no battle-proven live 4K super-slo motion units and the variety of camera angles which soccer fans in particular are used to, cannot yet be replicated in the higher res format. Spidercams, goal-cams, any cam requiring a wireless link, need upgrading to 4K.
It isn’t usually possible to increase light levels at sporting venues, so lenses need to be wide open, but the resulting shallow depth of field might prove a major limitation.
Lack of light will also make the job more difficult for high-speed cameras, particularly if the eventual frame rate of Ultra-HD is standardised at 120fps, as high-speed cameras would have to be three times as fast to offer the same slow-motion replays as today.
In light of this Sony’s test during the Confederations Cup last June is illuminating. Seven F55 cameras were trained on the action alongside two HDC-2500s upconverted to 4K via prototype board.
A mix of high-end Fujinon digital cinema lenses requiring external control for focus, zoom and iris and mid-range motorised Fujinon Cabrios were tested. There were also tests for use of several 2/3” HD lenses with a special adaptor.
Optical fibre ran the raw data from the F55 back to BPU-4000 baseband processors in the truck. These are 1U rackmount units designed to debayer the RAW data and output four seperate HD signals for transport at 3Gbps.
Importantly, the BPU-4000s were connected to 3G HDI CCUs providing power and traditional broadcast camera control functions to the F55 camera head.
“As far as the CCU is concerned it is talking to a standard camera as the processing that is done in the camera head for HD is done in the BPU-4000,” explains Sony’s live production manager Norbert Paquet.
“When the operators rack focus and zoom it’s as if they were using a standard broadcast lens. As far as the camera operators were concerned this was a totally traditional workflow.
“We were scared of shallow depth of field but in the end, whether we were shooting wide angles positions with 2/3” or 35mm sensor we found the picture doesn’t change that much. There’s still enough depth of field to cover the action correctly. For zoom it’s bit shallower for sure but the big box HD lenses worked perfectly here, so much so that it was difficult to make a distinction between 4K native lenses and a box HD one.”
Having invested in the F55 and satisfied of its operational value for 4K live, Sony are not the ones to release a 2/3 inch 4K camera. Nor is Grass Valley, another key outside broadcast camera maker. “We are looking at how to achieve higher resolutions for live broadcast and concluded that there are some physics limitations to doing it using 2/3” chip cameras,” says Matt Allard, VP marketing.
“If we stay with 3x 2/3” chip cameras and make it 4K then there are lighting issues. If we go with bigger sensors we have lens issues. So we are looking at technology to come to a physics compromise. To do 4K, some physics needs to change.”
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4K Features to TV drama
There are only a handful of options for 4K acquisition currently available, notably Red’s One and Epic, Sony F65/F55/F5 and Canon C500 but plenty more will appear over the next year.
The latest version 3 firmware for the F65 includes support for a new OLED viewfinder (already in use on the F55) and 48fps operation. Using Sony’s RAW Viewer application 6K or 8K data can be captured from the chip, exported as DPX.
Both F55 and F5 feature new anamorphic lens options and at the end of September will add HFR capability for 2K 240fps or 4K 60p – the maximum these units will achieve. For higher 4K rates, the F65 will reach 120fps. Yet another Sony option is the FS-700 which can record 4K with an external recorder.
The Epic continues to be popular for acquiring films (such as Pain & Gain) or special sequences (I.e Rush) and users can even capture up to 6K resolution by upgrading the sensor to the Dragon, reckoned to be two times the resolution of the original 4K Red One chip.
As with its 2K predecessor, Blackmagic Design has had a few issues getting its 4K camera out of the door, though it is scheduled to ship by IBC. The model features a global shutter and outputs 4K compressed in CinemaDNG RAW and ProRes 422 (HQ) file formats via SSD.
JVC has a 4K camcorder, aimed more for prosumers and GoPro’s Hero3 is nominally 4K and 24fps capable though it’s not clear if any significant production has shot and used its images. For hi-speed action on select sequences the Phantom is always a good bet. The Flex, released at NAB, can produce 1000fps 4K imagery.
Although it sports a 3.5K sensor the Arri Alexa remains extremely popular. Cinematographers appreciate its ergonomics and that the optical design is not entirely geared to maximising pixel density, but to achieving dynamic range too (up to 14 stops of exposure).
4K London, a DIT and kit crewing and rental house through which many UK-shot digital features now pass, reports that demand for the Red has dropped a little following the dip in demand for 3D projects, while the Alexa remains strong. It was used by highly regarded DP Roger Deakins to shoot Skyfall at 3.5K, upscaled to 4K for Sony screen projection.
Arri is working on the next generation digital camera which will have at least 4K resolution and high-frame-rate capability.
According to the company’s managing director Franz Krauz: “We are working on technology that will offer a higher spatial resolution but also pushing hard in terms of a higher temporal resolution, without sacrificing the dynamic range we can already deliver. We don’t want to produce one camera that has high contrast and another with high detail.”
We should also note that another legendary name from film, Panavision, is also developing a digital camera rumoured to sport a 70mm-sized sensor.
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Most modern lenses cover a 30mm diagonal, sufficient for 35mm sensor cameras, and resolution is not an issue. “The answer to the resolution required for 4K is something just under 40 line pairs per millimetre,” says Cooke Optics chairman Les Zellan.
“We’ve pulled on-axis over 200 line pair, and the only reason we don’t know we’re not pulling more is that our reticle only goes up to 200 line pair. But even on those numbers that means our lenses are good enough for 20K.”
That said, the classic Cooke Speed Panchro, the first high-speed cinema lens which ceased prodution in the early 1970s, is getting an upgrade for the 4K era.
True Lens Services has started a Speed Panchro conversion project that will equip hundreds of the lenses with a PL mount and Cam Form focus mechanism to fit today’s digital cinema cameras for about U$20,000 a set.
At Carl Zeiss, Michael Schiehlen, sales director declares: “4K is not a challenge for us. All our cine primes and zooms are 4K+ compatible.”
IBC will be the first time the company has shown its complete range of three Compact Zooms. “They are the only cine style zooms that cover the full frame sensor size of 36x24mm (image circle of 43mm),” he says. The glass is colour matched to all Zeiss Primes.
Solid State Recorders
Synonymous with Arri workflows, Codex Onboard S can record 4K from Canon C500 at up to 120fps with a capture drive. Codex Vault 2 is a workflow system (archiving, QC, sound-synced dailies) that works with Sony F55/F5 and Red.
“Vault can be used on-set or near-set to quickly clone camera original data from Sony AXSM cards or Red MAGs (and Codex Capture Drives) to internal storage,” says Sarah Priestnall vp market development.
“Then, material can be archived to dual LTO tapes and played back and QCed using the new Codex Review module. Dailies can be generated to various formats (Avid DNxHD, Apple ProRes etc) with look-up tables and burn-ins applied.”
Codex Review, previewed at NAB, is a module for Vault allowing playback of camera original material to a calibrated monitor, with a full colour pipeline, including ACES.
AJA’s Ki Pro Quad will capture files in 4K and Quad HD for fast track camera-to-editorial with 10-bit 4:4:4 support. It accepts RAW output via SDI simultaneously outputting that data via Thunderbolt.
The recorder includes an uncompressed and debayered 4K monitoring output and is (claimed) the only one supporting live debayering of 4K Canon RAW with simultaneous recording to ProRes 422 / 444 files.
Australian vendor Atomos doesn’t yet have a native 4K hard disk recorder. “By early next year there will be a plethora of 4K cameras at affordable prices,” said Jeromy Young, CEO and Founder. “We believe the true catalyst for 4K will come when people are using Sony handycams and DSLRs from Nikon and Canon in 4K on a regular basis.”
With Samuari today users can take compressed HD versions of 4K files along with all file naming, timecode and metadata tagging straight from Sony, Red and Canon cameras into editing and colour correction packages for offline editorial before conforming with the higher resolution originals.