With the announcement of the ALEXA LF, ARRI has finally made a camera that has a sensor bigger than 4K (that is if you don’t count the ALEXA 65). ARRI has never been a company that gives into market pressure, and the fact that they have waited this long to finally release a camera you can buy (the ALEXA 65 is rental only) that can record a proper non-upscaled 4K or larger image is a testament to that. ARRI has always been about better pixels, not bigger pixels.
If you haven’t seen the announcement, check it out along with our video coverage here.
ARRI has never chased resolution, they have always been about delivering the best possible pictures, but times have changed, and certain companies such as Netflix will only take content shot on a camera that is capable of recording a 4K image. Even though the ALEXA SXT and MINI can both upscale to 4K UHD, Netflix wouldn’t except the content. This frustrated some cinematographers who were forced to use other camera brands when they would have preferred to shoot on ALEXA.
With the launch of the ALEXA LF, I thought it was a good time to have a look back at the evolution of the ALEXA camera that was first introduced almost eight years ago.
The ARRI ALEXA debuted way back in April 2010. The camera wasn’t ARRI’s first foray into digital cinematography, that came in the form of Arriflex D-20 and D-21. The ALEXA series of cameras went on to become the defacto standard for high-end episodic TV, commercials and feature films across the world.
The ALEXA was a huge step up over the Arriflex D-21 and it combined a Super 35 sized 3.4K CMOS sensor that could shoot in resolutions of up to 2880×2160 (2K) with the ability to capture uncompressed video or proprietary raw (ARRIRAW) data.
The science of the sensor
The ALEXA ALEV III (28.17×18.13mm) sensor has a pixel size of .00825mm, and even today, more than seven years after it was first announced, it’s still considered one of the best sensors on the market. This is a true testament to just how good this sensor is. The ALEV III sensor oversampled images intended for HD or 2K distribution. This oversampling has become commonplace amongst manufacturers who build sensors for digital cinema cameras.
One of the reasons the ALEV III is slightly larger than a Super 35 frame, was so users could see 10 percent beyond the edges of the recorded frame. This capability is crucial so you can see what is going to come into frame. At the time this functionality was only available to optical viewfinders but was unheard of in any type of electronic viewfinder.
Unique for a digital sensor was the height of the ALEXA sensor, which allows a number of sensor modes only available in ALEXA cameras, including those needed for shooting with anamorphic lenses. The sensor’s 3.4K horizontal photosite count delivered unusually large photosites for an optimal balance between image sharpness on the one hand and high dynamic range, high sensitivity and a low noise floor on the other.
Although the science behind the breakthrough performance of ALEXA’s custom-designed CMOS sensor is complex, the use of large photosites and a Dual Gain Architecture are its two main principles. By employing unusually large photosites (in today’s world of tiny cell phone sensors), ALEXA’s sensor exhibits high dynamic range, high sensitivity, and low crosstalk. The larger a photosite is, the more light it can capture and the lower the noise.
The Dual Gain Architecture simultaneously provides two separate read-out paths from each pixel with different amplification. The first path contains the regular, highly amplified signal. The second path contains a signal with lower amplification, to capture the information that is clipped in the first path. Both paths feed into the camera’s A/D converters, delivering a 14-bit image for each path. These images are then combined into a single 16-bit high dynamic range image. This method enhances low light performance and prevents the highlights from being clipped, thereby significantly extending the dynamic range of the image.
Making the switch from film to digital
The ALEXA was arguably the first camera that persuaded a lot of DP’s to make the switch from film to digital.
Perhaps the biggest compliment the camera ever got was from Roger Deakins after he shot the James Bond film Skyfall. Deakins said “The Alexa’s tonal range, color space, and latitude exceed the capabilities of film. This camera has brought us to a point where digital is simply better.”
The ALEXA system is based on an open architecture, with many industry-standard interfaces and compatibility with third-party products. This provides more choice to the filmmaker and, in combination with the range of upgrade options available, makes the system more future-proof. To protect customers’ investment in ALEXA, frequent software updates were provided free of charge, continually expanding the feature set.
Three major components were specially designed to allow an easy upgrade path. First, the Storage Interface Module is removable, in anticipation of different memory card standards becoming available. Second, the Electronics Interface Module could be replaced with an upgraded unit such as the ALEXA Plus side panel. Finally, the Exchangeable Lens Mount allows the use of PL, Panavision and stills camera lenses, extending creative options still further.
Perhaps the most overlooked and underappreciated aspect of the ALEXA was the onboard recording to either Apple ProRes 4444 or ProRes 422 (HQ) codecs using Sony SxS memory cards. This internal recording could also be done while simultaneously outputting uncompressed HD or RAW. The ability to take a SxS card from the ALEXA, slide it into the ExpressCard/34 slot of a 17-inch MacBook Pro and watch material instantly was huge at the time.
There have been ten different cameras in the ALEXA family introduced over the years, so let’s have a look at all of them. The ALEXA series can be broken down into 3 groups:
ALEXA CLASSIC Cameras
ALEXA XT Cameras
ALEXA SXT Cameras
ALEXA CLASSIC Cameras
First generation ALEXAs are called ALEXA Classic cameras. They were released between 2010 and 2012. They have exceptional image performance and are simple to operate, reliable in the most extreme environments and versatile enough to cover a wide range of workflows and budgets. They will empower you to tell your story with pictures of breathtaking richness and detail.
ALEXA Classic camera models are the:
- ALEXA Plus
- ALEXA Plus 4:3
- ALEXA M
- ALEXA Studio
- ALEXA HD
- ALEXA HD Plus.
The ALEXA HD and HD Plus are the basis for the ALEXA Fiber Remote and Fiber Remote Plus camera sets. All ALEXA Classic cameras are equipped with an SxS Module located on the left side of the camera with two slots for SxS PRO or SxS PRO+ cards.
ALEXA Classic cameras can be upgraded with the XR Module and other parts for most of the features of ALEXA XT cameras except Open Gate sensor mode.
The ALEXA used the ALEV III CMOS sensor (3392×2200 effective pixels) and could shoot in resolutions up to 2880×2160. It had a PL mount and supported the recording of uncompressed video or proprietary RAW (ARRIRAW) data. The ALEXA’s CMOS Super 35mm sensor was rated at ISO 800. That sensitivity allowed the camera to see a full seven stops of overexposure and another seven stops of underexposure, an unprecedented 14+ stops of dynamic range, which at the time was unheard of for digital capture. The 14+ stops of range was available over the entire sensitivity range from EI 160 to EI 3200
The ALEXA Plus added integrated wireless remote control, the ARRI Lens Data System (LDS), additional outputs, lens synchronization for 3D, and built-in position and motion sensors.
ALEXA PLUS 4:3
The ALEXA Plus added integrated wireless remote control, the ARRI Lens Data System (LDS), additional outputs, lens synchronization for 3D, and built-in position and motion sensors and a 4:3 sensor which enabled the camera to shoot in a 2x anamorphic mode.
The Alexa M had its imaging and processing unit broken down into two parts to be small, compact and lightweight for 3D rigs and to use in spots where a traditional ALEXA couldn’t go.
The Alexa Studio featured an optical viewfinder, mechanical shutter, and a 4:3 sensor.
The ALEXA HD was a “budget” (well at least as far as ARRI cameras go) camera that shared the same 14 stop dynamic range, native ISO of 800, SXS card capture, and C-log recording in 10bit up to 120FPS. It used the same ALEV III CMOS sensor found in the standard ALEXA, but only allowed users to record in 1920×1080 resolutions.
ALEXA XT cameras
Second generation ALEXAs are called ALEXA XT cameras (Xtended Technology). They were released between 2013 and 2016. In addition to all the features of the ALEXA Classic cameras, they are equipped with a Super 35 sensor (with Open Gate and 4:3 sensor modes), in-camera ARRIRAW up to 120 fps, ProRes 4444 XQ, ProRes 3.2K, internal ND filter, Lens Data System, integrated CDL capture and ARRIRAW checksum. In addition, they have a new viewfinder mounting bracket, include anamorphic de-squeeze and high speed licenses as well as a new, super silent fan. ALEXA XT cameras are the ALEXA XT, ALEXA XT Plus, ALEXA XT M and ALEXA XT Studio. The XR Module is on the left side of the camera. It has one slot for either an XR Capture Drive, the SxS Adapter for use with one SxS PRO or SxS PRO+ card or the CFast 2.0 Adapter for use with one CFast 2.0 card.
In February 2013, ARRI unveiled the ALEXA XT (XT standing for extended technology). The XT was an upgraded version of the original ALEXA cameras. It added an XR module, which replaced the SxS module. This XR module allowed RAW recording without the need for an external recorder. Further improvements included an internal ND filter unit, a 4:3 sensor and a quieter cooling fan.
ALEXA SXT cameras
Third generation ALEXAs, released in 2016, are called ALEXA SXT cameras (Super Xtended Technology). While keeping the sensor and user interface of the original ALEXA design, the capabilities of ALEXA SXT cameras have been greatly extended. Equipped with the powerful electronics and sophisticated image processing from the ALEXA 65, SXT cameras can manage more recording formats and handle more processor-intensive tasks such as calculating looks with 3D LUTs or color space conversions to Rec 2020, all in real time. Building on work done originally for the ALEXA Mini and AMIRA, the new ARRI looks management and optional noise reduction help creative filmmakers get their ideas across. And last but not least, the new media bay can accept a wide range of media, as well as the new, high-performance SXR Capture Drives.
ALEXA SXT cameras are the:
- ALEXA SXT EV
- ALEXA SXT Plus
- ALEXA SXT Studio
The SXR Module is on the left side of the camera. It has one slot for either the XR Adapter for use with an XR Capture Drive, the SXR Adapter for use with an SXR Capture Drive, the SxS Adapter 2 for use with one SxS PRO or SxS PRO+ card or the CFast 2.0 Adapter 2 for use with one CFast 2.0 card.
On 18 March 2015, ARRI announced the SXT line of ARRI ALEXA cameras which supports in-camera upscaling of Apple ProRes to 4K (UHD) resolution and Rec. 2020 color space. Arri also announced the SXR module which can upgrade XT, XT Plus, and XT Studio cameras with the SXT features.
Other ALEXA cameras
On 21 September 2014 at the Cinec convention in Munich, ARRI announced the ALEXA 65, a 6k 65mm digital cinema camera.The camera features a sensor that is slightly larger than a 65mm 5-perf film frame and is comprised of three ALEXA sensors that are arranged vertically and seamlessly stitched together.
The ALEXA 65 has subsequently become the go-to large-format solution for high-end theatrical motion pictures. ARRI initially only built 30 cameras and due to the increased interest and high demand, they built another 40 cameras. This brings the total up to 70 units worldwide. The cameras are only available through ARRI Rental. The ALEXA 65 has become so sought after that there is a long waiting list for anyone who wants to use one. The camera has been used on films such as the Revenant, Wonder Woman, Mission Impossible – Rogue Nation, Transformers – The Last Knight, Okja, Rogue One, The Dark Tower, War For The Planet Of The Apes, Life, and Thor – Ragnarok just to name a few.
On 24 February 2015 Arri announced the ALEXA MINI. It has the same sensor as the other Alexa cameras but was a shrunken down version of the larger ALEXAs that was meant to be for drones, gimbals and crane use. Little did ARRI know at the time, that the MINI has gone on to become probably the most widely used of all the ALEXA cameras. The MINI features in-camera recording to CFast 2.0 cards, the ability to record up to 200 FPS and 4K UHD in-camera upscaling. It can also shoot at various resolutions, including 4:3 open gate.
Continuing the legacy
Just like previous Arri cameras, the ALEXA has become the modern digital industry standard in many ways. The camera has been used in high budget feature films, television shows, and commercials by some of the world’s leading cinematographers. Movies shot on the ARRI ALEXA digital platform have won the Academy Award for Best Cinematography 5 times in a row respectively for Hugo (2012), Life of Pi (2013), Gravity (2014), Birdman (2015) and The Revenant (2016).
ARRI ALEXA cameras were also used in the following films that won the Academy Award for Best Picture:
The newest ARRI ALEXA LF looks like it will continue the ALEXA legacy and once again reaffirm ARRI’s position as being the industry leader in digital cinema cameras. ARRI have proven time and time again that it’s not the resolution that matters, and many cinematographers agree. With this new increase in resolution and the same fabled “ALEXA Look”, the LF is sure to be a hit with cinematographers all over the world.