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The Arri Alexa (stylised as ΛLEXΛ) is a digital motion picture camera system made by Arri first introduced in April 2010. The camera was Arri's first major transition into digital cinematography after smaller previous efforts such as the Arriflex D-20 and D-21.
Alexa cameras are designed for use in high budget feature films, television shows, and commercials, and compete with Red Digital Cinema's line of high end cameras such as the Epic Dragon and Weapon Dragon. Alexa uses the ALEV series of image sensors manufactured by ON Semiconductor.
The camera has several methods of recording, including SxS cards, CFast 2.0 cards and SXR Capture Drives at resolutions up to 2880 x 2160 pixels in either Rec. 709 or Log-C to ProRes or ARRIRAW codecs. Alexa camera owners can purchase additional software licenses that will unlock different capabilities of the Alexa Camera including High Speed 120fps recording, DNxHD codec and 4:3 "Open Gate" Mode for anamorphic lenses.
The price of the camera depends on model and accessories; as an example, in 2015 an Arri Alexa XT cost approximately $66,000-100,000, depending on accessories included.
The range of Alexa models has expanded over time:
The first camera of the Alexa product family. The ARRI ALEXA’s CMOS Super-35mm sensor is rated at 2.8K and ISO 800. That sensitivity allows the camera to see a full seven stops of over exposure and another seven stops of underexposure. To take advantage of this, ARRI offers both industry-standard REC709 HD video output as well as the Log-C mode that shows the entire range of the chip’s sensitivity, allowing for an extreme range of color correction options in post.
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 4:3Edit
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 making it ideal for anamorphic cinematography.
The Alexa M had its imaging and processing unit broken down in two parts to be small, compact and lightweight for 3D rigs and other uses where size is a concern.
The Alexa Studio features an optical viewfinder, mechanical shutter, and a 4:3 sensor for anamorphic cinematography.
In February 2013, the range was renewed as Alexa XT (XT standing for extended technology). This range is upgraded versions of the original Alexa cameras, which are equipped with a so-called XR module, which replaces the SxS module on the cameras, and allows direct raw recording without the need for an external recorder. This module records on dedicated SSD drives. Further improvements are an internal ND filter unit, a 4:3 sensor and a quieter cooling fan. The range accordingly comprises the Alexa, the Alexa XT, the Alexa XT M, the Alexa XT Plus, the Alexa XT Studio, and the Alexa Fiber Remote. Existing cameras can be upgraded with the XR module for internal raw recording.
On 21 September 2014 at the Cinec convention in Munich, Arri announced the Alexa 65, a 6k 65mm digital cinema camera. As with cameras from competitor Panavision, the Alexa 65 camera was available by rental only, provided through the ARRI Rental Group. The Alexa 65 uses the A3X sensor, which has a maximum recordable resolution of 6560x3100.
In May 2015, Marvel Studios announced that Avengers: Infinity War and Avengers: Endgame will be shot entirely with the brand new camera, marking the first time a narrative feature film was shot entirely with a customized version of Alexa 65 camera, Alexa IMAX, as the camera had only been used to film specific scenes in Captain America: Civil War.
On 24 February 2015, Arri announced the Alexa Mini. It has the same sensor as the other Alexa cameras. It features in-camera recording to CFast 2.0 cards, 200 FPS and 4K UHD in-camera upscaling.
On 18 March 2015, Arri announced the SXT line of Arri Alexa cameras which will support in-camera upscaling of Apple ProRes to 4K 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.
On 2 February 2018, Arri announced the Alexa LF at the BSC Expo. It's a true 4K Large Format Camera. The ALEXA LF’s A2X sensor is based on two vertical ALEV-III sensors, which are stitched together to create a seamless large format image. This is the same principle of how they created the ALEXA 65, which uses three Alexa sensors that are arranged vertically. The ALEXA LF can record in Open Gate in a resolution of 4448 x 3096.
Alexa Mini LFEdit
On 28 March 2019, Arri announced the Alexa Mini LF, which houses the same sensor as the Alexa LF inside a camera body similar to the Alexa Mini. Additional improvements over the Alexa Mini include an improved EVF (MVF-2) with larger flip-out monitor and power outputs for camera accessories. The camera also features a new Codex recording module, which accepts 1TB Codex Compact Drives. 
The Alexa's ALEV III image sensor has 3392×2200 effective pixels used for generating an image, 2880×2160 pixels are generally used for recording on the Alexa Studio and M in 4:3 mode, and 2880×1620 pixels are used for recording on the regular Alexa and other models in 16:9 mode, the rest of the sensor is used for lookaround in the viewfinder. Alternately the full sensor resolution may be employed in 'Open Gate' mode for resolution demanding situations.
The Alexa 65 uses the A3X sensor, which has a 54.12 mm x 25.59 mm active imaging area. It provides up to 6560x3102 'Open Gate' maximum recordable resolution.
The Arri Alexa can record to 1920×1080 ProRes 422 or ProRes 4444 on SxS Cards or 2880×1620 ARRIRAW to external recording devices. The Arri Alexa Firmware 7 increases the resolution on the SxS cards to 2k ProRes 4444 (previously 1080p)
ArriRaw is a raw codec similar to CinemaDNG that contains unaltered Bayer sensor information, the data stream from the camera can be recorded via T-link with certified recorders like those from Codex Digital or Cineflow.
The ArriRaw format (along with the other recordable formats) contains static and dynamic metadata. These are stored in the header of the file and can be extracted with the free web tool metavisor or with the application Meta Extract provided by Arri. Of particular importance for visual effects are the lens metadata, which are stored only when Arri's lens data system (LDS) is supported by the lens used.
According to cinematographer Roger Deakins, 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", says Deakins. Deakins used the camera to shoot the James Bond film Skyfall, Unbroken, Sicario, Prisoners and the Academy Award for Best Cinematography winner Blade Runner 2049.
Due to the camera's simplicity of use and high image quality, several network television shows have been shot with the Alexa.
Since its introduction, six movies shot on Alexa (Argo, Birdman, Spotlight, Moonlight, The Shape of Water, and Green Book) won an Academy Award for Best Picture. Also, movies shot on Alexa won Academy Award for Best Cinematography seven times, including five in a row between 2011 and 2015, for Hugo, Life of Pi, Gravity, Birdman, The Revenant, Blade Runner 2049, and Roma.
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The basic camera package will cost you about $66,575. And with accessories, this price can easily reach $100,000 with the addition of XR drives, remotes, licenses, cables and add-on hardware.
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