Explore the Features and Workflow of the ALEXA LF with ARRI

Ever since its unveiling earlier in the year at the BSC Expo in London, the new ALEXA LF has been getting the attention of industry personnel in both high-end production as well as rental houses looking to capitalize on the “large format” trend in modern cinematography. Whether going “full-frame” or said in other words “large format” (now serving as a catch-all phrase for any top-end camera with a chip bigger than S35) has replaced the “K” race in the world of cinematography remains to be seen, however all the indicators of bigger sensors taking over the so-called resolution wars at least for the moment are there.

All major manufacturers (apart from Panasonic, which I am hoping they bring out something new soon in the Varicam range maybe a Varicam FF?) have jumped on the Large Format bandwagon – RED has been doing this with their Dragon VV sensor and more recently with their 8K Monstro sensor, Sony have the 6K Sony VENICE, even Canon went full-frame and 4K+ with the C700 FF.


ARRI ALEXA LF at BSC Expo 2018

It was only a matter of time before ARRI made a “true” 4K camera whatever that means. Whether it was pressure from the competition, which was getting most Netflix jobs, or simply “the plan all along” doesn’t really matter – the ALEXA LF is here and it is a beast.

For those who have yet to see it in person whether at NAB, Cine Gear or aforementioned BSC Expo, it has all the hallmarks of an ARRI product – meticulous, reliable, built-t0-last design where everything has been thought, and re-thought countless times to encapsulate a product designed to work all the time an provide world-class images.

To get rental houses, ACs and DPs up to speed with what the LF can do, ARRI have released a new video series introducing potential users to the features, sensor, new lens mount and workflow of the ALEXA LF. Much like all ARRI Alexa cameras before it, the ALEXA LF has been designed to work seamlessly with the existing Pro Accessories, lenses, wireless control, and most of all the established and industry-standard ALEXA workflow.

Like the ALEXA SXT, the LF has four independent monitoring outputs, which can be set independently (one is used by the viewfinder), with MON1 and MON2 being 6G-SDI compliant for a 4K/UHD 30p output. All three outputs on the back can be set for SDR or HDR monitoring on set or in the studio.

Unlike the older ALEXA models however, switching between sensor modes does not require reboot and can takes about 20 seconds or less, saving you time.

The ALEXA LF harnesses a lot of processing power and is therefore not compatible with 12v on-board batteries; Third party manufacturers such as Hawk-Woods do however offer 26v REEL Power batteries and a battery plate adapter (see previous post on these here); in addition, Bebop also offer an adapter and 14.4v High power draw battery with voltage booster to get the voltage to 20v, the minimum the LF would accept.


Unlike the ALEXA 65, which is a rental only option and has a larger sensor requiring medium-format lenses, has a sensor that is basically comprised of three ALEXA S35 sensors jammed together, the ALEXA LF sensor is slightly “smaller” and it measures at 4448 x 3096 (36.7mm x 25.54mm, meaning it is slightly larger than photographic full frame).

This sensor configuration makes the ALEXA LF capable of three sensor modes (in either ARRIRAW or ProRes) – all approved for Netflix production. The ability to record ProRes in various flavours including 4444 and 4444 XQ, unlike the Alexa 65, makes the LF a much more flexible solution for high-end 4K acquisition and delivery.

You can look at the ALEXA LF sensor as 2 x S35 ALEXA sensors (ALEVIII) stitched together using the same photosites and colour sciences as the rest of the ALEXA lineup, giving you that familiar ALEXA look. However,

ARRI ALEXA LF Sensor Modes:

  • Open Gate:
    • 36.70 x 25.54mm (4448 x 3096) at up to 90fps
    • 44.71mm image circle coverage area
    • No surround view
    • Max resolution, uses full sensor area
  • LF 2.39:1 
    • 36.70 x 15.31mm (4448 x 1856) up to 150fps
    • For full-frame spherical lenses
    • 39.76mm image circle coverage
    • No surround view
  • LF 16:9
    • 31.68 x 17.82mm (3840 x 2160) up to 90fps
    • 36.35mm image circle coverage
    • Has surround view
    • Some S35 lenses can cover this mode
    • 24mm and longer ARRI ULTRA Primes cover this mode
    • 35mm and longer ARRI Master Primes cover this mode

The Large Format image:

Designed to be primarily used with large format lenses such as their new Signature Primes, ARRI have also made it possible for DPs to use industry standard S35 and full-frame PL (positive Lock mount) lenses on the ARRI ALEXA LF thanks to their innovative PL to LPL adapter (the native mount on the ALEXA LF is LPL). Interestingly enough, ARRI are also going to license this LPL mount to other camera and lens makers, so I would expect third party lenses in such lens mount in the future, and even cameras.

ARRI LPL-to-PL adapter:


ARRI have made available a few very helpful tools for the ALEXA LF – the ARRI Lens Illumination Guide, Frameline Composer and Formats & Data Rate Calculator to help your DP or DIT in pre-production. In the LF 16:9 mode, users can also record ARRIRAW or ProRes in 2K in addition to 4.5K for proxy editing or delivery with lower resolution requirements.

Learn more about the ARRI ALEXA LF large-format camera system and play around with its Menu Simulator head over to ARRI’s dedicated LF portal here: https://www.arri.com/largeformat/

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