We've heard some talk about a 4K ARRI camera, and even a rumor about a 6K 65mm camera from the company, but nothing has really materialized until now (mostly because they haven't felt it was necessary). The first 4K camera from ARRI will not be a new model, but a software update to the AMIRA that will let it shoot internally to ProRes at 3840 x 2160 UHD up to 60fps. The AMIRA, which has recently started shipping and is being used extensively by NFL Films, will get the software update by the end of 2014. But what about the fact that the AMIRA and the ALEXA share sensor technology and ARRI doesn't yet have a 4K sensor in their cameras?
From their press release, the company is apparently upsampling the 3.4K sensor in their camera to 3.8K (cameras that don't ship with the update will need to be recalibrated):
For major feature films, an up-sample to 4K can be carried out after visual effects and other postproduction tasks have been completed at 2K resolution. For certain fast-paced AMIRA productions, however, there may not be the time or resources for such processes in post, which is why a 4K or UHD output direct from the camera has been requested.
AMIRA’s UHD output utilizes the same efficient 1.2x up-sample filter that allows ALEXA’s Open Gate mode to optimize the camera’s image performance for 4K distribution, as well as the same best-in-class sensor pixels. The up-sample to UHD happens in camera, and in real time.
This page on their site also seems to suggest that you may be able to send out a UHD signal from the camera at some point:
It's been mentioned that the 16:9 AMIRA has the same sensor featured in some ALEXA models, but a few things could be happening. Either the sensor has always been 4:3 and they've simply called it 16:9 when the hardware wasn't capable of more, or there are different 16:9 and 4:3 sensors that both feature the same 3.4K resolution. It's more likely that it has been the same 4:3 sensor that has been limited in certain models due to the internal hardware.
Here is ARRI talking about their Open Gate mode on the ALEXA XT, which ARRI is saying is the same thing happening internally with the AMIRA UHD update (the AMIRA is probably being cropped to 16:9 or 1.78 from the full 1.55:1 aspect ratio):
Here is a look at the different recording areas of the ALEXA, showing the full sensor area outlined in black:
Even though they may have 4K in the works in a different model, ARRI is offering this now since it's something other cameras already have and certain productions actually want:
While widespread adoption of 4K or UHD for broadcast is still a long way off, an increasing number of content owners are becoming concerned that they ought to safeguard the longevity of their programs by ensuring that they will be suitable for UHD transmission, should that become a standard in the future.
For those productions that do need to generate UHD deliverables, AMIRA will now offer the ability to record all ProRes codecs in Ultra High Definition 3840 x 2160 resolution directly onto the in-camera CFast 2.0 cards, at up to 60 fps. This feature, activated through an affordable software license (and a sensor calibration for existing AMIRAs), comes in response to feedback from AMIRA customers, some of whom have been quizzed about 4K deliverables by clients. It is made possible by the camera’s exceptional image quality, its processing power, and its reprogrammable system architecture.
Whether a production is pursuing a UHD workflow all the way through to distribution, or simply wishes to archive in UHD in order to future-proof itself against industry developments, AMIRA now offers an easy solution that requires no additional processes in postproduction.
And here is who's using it (I'm sure NFL Films could also get some use out of it):
Wildlife cinematographer Rolf Steinmann, who was nominated for an Emmy Award this year in recognition of his work with ALEXA on the BBC’s Wild Arabia series, is currently using his AMIRA on a movie for Disney Nature. He comments, "For cameramen like me who own their gear, the UHD upgrade is a great way to stay future-proof. From now on when there's pressure from the production side to deliver UHD, I can continue to work with AMIRA and won't have to compromise on image quality or on the camera's robustness and reliability."
Even though ARRI is upsampling to get to UHD, it's only a slight upsample from their original pixel resolution, and plenty of cameras have done this in the past to get to 720p or 1080p, like the Panasonic HVX, some JVC models, and many more. The ALEXA has looked so good up to this point because ARRI has focused on giving better pixels, rather than just more pixels, and they've been downsampling quite a bit for even their 2.8K RAW mode, which gives sharper and cleaner images in the end. By going the opposite direction, they are now pushing their sensor in other ways. The Open Gate mode for the XT was meant more as a VFX or repositioning tool with some downscaling later, but this UHD ProRes recording is using this entire sensor natively to give you a 4K output.
Since the AMIRA is aimed more at broadcast, and broadcast for much of the world isn't at 4K yet, most of this material will still benefit from a downscale when it's shown at 1080p. It would certainly be interesting to see ARRI's 4K implementation and how that compares to other cameras that have native or (in the case of RED) much higher than 4K resolution. There is no doubt ARRI has fantastic engineers, so it would not be surprising in the least if a sub-4K image was still on-par, or even better, than some cameras that actually feature 4K or higher sensors.
It's unclear when we'll see a 4K model from the company, but there are obviously enough users asking for it that ARRI felt the need to enable it internally in one of their models.