Autor: Redaktion

Arri Alexa LF

Arri's complete large-format camera system

It is based on a large-format 4K version of the Alexa sensor and includes the camera system, the specially developed Arri Signature Prime lenses, the LPL lens mount and the PL-to-LPL adapter. It is also compatible with existing lenses, accessories and workflows.

The native 4K sensor has an image window of 36.70 mm x 25.54 mm, which is slightly larger than the classic full frame (36 mm x 24 mm). The LF Open Gate mode works with effectively 4448 x 3096 pixels (13.8 megapixels). In 16: 9 mode, it's 3840 x 2160 pixels (8.3 megapixels). The 2.39:1 mode has 4448 x 1856 pixels (8.25 megapixels).

Arri's natural colorimetry, smooth skin tones and proven suitability for high dynamic range and wide color-gamut workflows continue in this camera. Versatile recording formats such as ProRes and the uncompressed, unencrypted ARRIRAW with up to 150 FPS, offer familiar flexibility in post production.

The sensor’s base sensitivity is ISO800. The contrast range is 14 f-stops.

Optimized for large-format sensors, the LPL mount has a larger diameter and shorter flange focal distance (FFD), enabling ARRI Signature Primes and all future large-format lenses to be smaller and lighter.

Arri Signature Primes

The ALEXA LF offers the same workflow as other ALEXA cameras. Operators can use the ARRI look files, and all ARRI Workflow software tools support ALEXA LF images. Lens metadata can be recorded by LDS-1, LDS-2 or / i lenses.

The system can record in ARRIRAW or Quicktime/ProRes (422,422HQ, 4444, 4444XQ), onto SXR Capture Drives (1TB/2TB) or onto SxS Pro+ 256GB for ProRes only.

Using Open-Gate or 16:9 modes the Arri LF can capture up to 90 FPS for ARRIRAW and up to 60 FPS for ProRes. In 2.39:1 mode the system can capture up to 150 FPS in ARRIRAW format, or up to 100 FPS in ProRes.

In terms of resolutions the LF can work up to 4.5K in Open-Gate and in 2.39:1 mode, UHD-1 in 16:9 mode and 2K or HD in 16:9 mode (via an internal downscaler)

The Monitor Out delivers the following signal choices:

• MON OUT 1a, 1b and 2: SDI 6G UHD or SDI 1.5G HD up to 30 FPS.
• MON OUT 3: SDI 1.5 G HD up to 30 FPS or via ARRI Wireless Video  (1080p up to 60FPS)
• Anamorphic de-squeeze for 1.25x, 1.3x, 1.5x, 2x Lens Squeeze Ratios

The sensor signal can be processed as 16 bit linear in the “ALEXA Wide Gamut” and Log-C as well as the following output color spaces: Log-C, Rec709 or Rec2020. ARRI Look File (ALF-2) with CDL (Color Decision List) as well as 3D LUTs for SDR (Standard Dynamic Range), HDR PQ, HDR (High Dynamic Range) and HLG (Hyper Log Gamma) are available.

The camera body weighs 7.8kg.

The first ARRI Alexa LF cameras went on sale in  March 2018. The first Signature-Prime lenses with focal lengths of 35mm, 47mm, 75mm and 125mm are expected in June 2018 with the remaining focal lengths later in 2018.

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