Camera kits

ARRI Alexa, all you need to know about the Alexa range of cameras

Alexa EV, Plus, Studio and the new XT Range explained.

ARRI recently announced the introduction of a new Alexa camera series, the ‘XT’ which has a different on board recording module compared to the other established cameras in the series and will replace this range. As the Alexa range is now effectively a ‘fleet’, we at VMI feel at this stage a short précis of each camera’s parameters and functionality is appropriate in order to enable producers and production companies to target the correct package at an early stage of preparation.


All Alexas:

The Alexa camera was conceived as a digital ‘film’ camera and to that end ARRI have engineered the Alexa with the ‘language’ and simplicity of film cameras that other manufacturers seem unable or unwilling to address. The ‘real world’ significance of these attributes is obvious to any 1st AC working in the lashing rain at 0300 in the morning! The main menu panel allows instant access to the four major parameters that need changing on a scene-to-scene basis, everything else, project settings, file numbering etc. are usually just one menu layer away.

The lens mount is PL (ARRI ‘precision lock’), which is now the ubiquitous standard for high end lenses. The Alexa  ELM system is incorporated into the aluminium body chassis for rigidity and depth stability-the only digital camera apart from the Sony F65 to not be a PL mount attached to another generic, manually releasable, mount (Sony E or A), or to have back focus ‘adjustment’ (RED), or be a plastic body (Canon C300). This solidity again results in 1st AC confidence as all lenses will scale and remain accurate throughout the course of a production.

The bodies of the cameras have built in adaptability for 15mm mounted accessories and base plates to become 19mm compatible or ‘V shoe’ documentary quick release plates.

The dynamic range or latitude of the cameras is dictated by the gamma selected to the record path. Available gammas are REC709 (standard HD video), Log C ( a 13 stop extended range masterpiece) and LCC a hybrid of the above. All narrative drama work that VMI supply shoot in Log C to benefit from the subtleties in tonal gamut.

All cameras have a high native EI rating of 800. The range is from 160-3200EI and the point where highlight and shadow recording ability is an equal spread is at the 800EI point. This sensitivity allows DPs to tell their stories in a naturalistic way as the camera will be able to gather an exposure level in any low light level circumstances.

All cameras will deliver FPS up to 120fps in 16:9 mode* and the system will indicate the highest quality codec available at these speeds (Note that these are ARRI chargeable options but standard from VMI and most Rental Companies).

All cameras feature an electronically adjustable shutter  (except the Studio), indicated in degrees as per a film camera.

Alexa EV:

The basic Alexa features a 16:9, Super 35mm sensor, which is capable of delivering the following headline recording resolutions.

The camera delivers the on board recording codecs to the SXS module on the side of the camera and with viewfinder weighs 7.7kilos.

Alexa Plus 16:9:

The Alexa Plus has an additional module on the right hand side of the body that contains additional operational functions. The sensor size and recording qualities are identical to the EV camera. The Plus basically has the receiver end of an ARRI wireless LCS (lens control system) which negates the need for an additional receiver box. However the majority of 1st ACs prefer a third party system manufactured by Preston (FI+Z3) and known colloquially as the FIZ, (focus iris zoom) and this has been regarded as a superior system to the ARRI LCS.

Recently introduced is a new ARRI system, called the WCU4, which does seem to address some of the old foibles of the LCS. However, the Plus is a kilo heavier (8.7 kilos) and if the ARRI WLCS system is not being used, there is no operational benefit and the recording qualities are equivalent to the standard camera. Additionally the Plus offers an electronic horizon (steadicam use) and an extra Monitor BNC out and GPS function.

Alexa Plus 4:3:

The 4:3 refers to the different sensor dimensions on this camera. This camera offers the following recording options as well as those listed previously under the standard camera.

 - ARRIRAW, 2880 x 2160 12 bit Raw
 - ProRes 2K, 2880 x 1536 (down sampled from 2150)

This camera can operate in 16:9 mode and is the same as the standard camera both operationally and recording quality wise in this configuration. The 4:3 sensor dimensions allow the use of full Anamorphic squeeze lenses on this camera. Anamorphic lenses squeeze double the horizontal optical information to give an un-squeezed aspect ratio of 2.35:1 for the full widescreen appearance. The unique focus and flare look of anamorphics we all know and love (see Star Trek for details…), but if you are not shooting Anamorphic there is no quality increase over a standard camera, so there is no additional benefit whatsoever.

Alexa Studio:

Referred to as the ‘high end’ Alexa simply because this camera has two complementary attributes that have been lost to digital acquisition. This camera features a mechanical shutter and as a consequence an optical viewfinder.

Operationally the benefits for the operator are a direct clean ‘feed’ from the lens, not a processed electronic picture, and there is a school of thought that champions a mechanical shutter action over that of an electronic one. Given the same premise that unless you are shooting anamorphic (or Skyfall), there is no increase in acquisition quality over the standard 16:9 camera, but there is an increase in weight to 10.8 kilos.

Alexa XT Range:

The evolution of the Alexa continues with the replacement of the SXS module on the side of the camera with a Codex derived SSD system.

All of the above camera grades are now supplied as XT versions from new by ARRI and all feature the following.

All cameras now have the 4:3 sensor, a new viewfinder mounting system (VMI have a rolling upgrade path to these as our cameras become available from long contracts), and an internal IR ND arrangement that can be kindly described as ‘fiddly’ - in order to change ND, you have to remove the lens, and then replace the magnetic ND filter inside the lens mount adjacent to the sensor.

The new XT module delivers all the above-mentioned codecs to 512gb SSD drives (but with the additional ability to deliver 120fps ARRIRAW) the obvious marketing  benefit being the additional storage time per card. A ProRes 4444 32gb card at 25fps is about 11 minutes so a 512gb SSD will be approx. 3 hours.

There will also be a caddy system to interface SXS cards into the XT module as well.  However, in our experience, ‘Alexa world’ shoots are wedded to the notion that a card lasts 10 minutes as did a 1000 foot roll of film, and that the ‘housekeeping’ mechanisms built around this workflow protect the days work in bite size lumps-it would be a brave production that would let an entire days work be recorded onto 1 SSD drive! However the overarching benefit is bringing the ARRIRAW recording capability within the body of the camera where the 512gb cards are needed for the high levels of data outputted and when a high pixel count for CG / process work is needed.

Production Requirement myth busting:

TV Drama, 16:9 SXS ProRes 4444 using with non ARRI WLCS system Standard Alexa EV.
Commercial/Promo/TV etc. using ProRes 16:9 4444  SXS with non ARRI WCLS system Standard Alexa EV.
Anamorphic Film using ProRes 4:3 2K 4444 SXS Alexa Plus/Studio
TV Drama, 16:9 using ProRes 4444 with ARRI WCLS system Alexa Plus
Slow Motion to 120fps ProRes All Cameras
ARRIRAW 2880 x 2160 (4:3) x 1620 (16:9)                                                      Alexa XT Range
  Standard Alexa EV with Gemini RAW external recorder
(in conjunction with the above parameters)  


In conclusion, there is no quality difference between a standard Alexa and all the other variants for ‘normal’ work, the Pluses are needed for Anamorphic work and the new XTs permit easier than ever ARRIRAW acquisition with 4:3 sensors, but ALL cameras in 16:9 mode have the same recording paths to SXS cards. Please contact Ian or Gerard at VMI for advice if required.

Ian Jackson Assoc BSC, VMI
May 2013








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