ARRI ALEXA 35 4K Digital Camera User Guide
- June 14, 2024
- ARRI
Table of Contents
ALEXA 35
Getting started with Workflow & Post
GUIDELINE
Date: September 27th , 2022
Introduction
This document gives you a brief workflow overview on how to work with ALEXA 35. We will update this document from time to time and later add additional information to our website in the Learn & Help section.
Major changes in the ARRI ALEXA 35
2.1 Technical updates & specifications
With the ARRI
ALEXA 35 we introduce a completely new sensor with a physical S35 size of
27.99 x 19.22 mm / 1.102 x 0.757″, ⌀ 33.96 mm, 4608 x 3163 photosites and a
significantly increased dynamic range.
2.2 MXF container & metadata
We also introduce a new MXF wrapper and metadata format that is used for both
MXF/ARRIRAW and MXF/Apple ProRes files. The technical specs regarding the
metadata are available publicly in SMPTE RDD 54 and SMPTE RDD 55. All metadata
is stored in each file header automatically. There’s no exception or
limitation.
2.3 File & Reel Naming
ALEXA 35 introduces a new and extended file naming to cater needs of
productions we’ve gathered in feedback over the years. The new naming provides
704 different options to set a Camera Index, 9999 reels and 999 clips. In
addition, an extended time stamp has been added as well as a “Codec
Identifier” to differentiate MXF/ARRIRAW and MXF/ProRes already on a file
system base:
New Reel Name (= folder name on the media)
The reel name follows the known scheme and consists of camera index, reel
counter and camera serial number.
2.4 ARRI Textures
To further open the creative possibilities within the ALEV4 sensor we have
created “ARRI Textures”. A texture changes a set of parameters that directly
influences the image. Among those are e.g., grainstructure, sharpness, and
others which in combination work
like a film stock.
ARRI Textures are offered as presets right in-camera and are not user
editable.
ARRI Textures are a destructive feature and cannot be altered afterwards! This
applies to both ARRIRAW and ProRes.
The texture “K445 default” is the default texture of ALEXA 35.
Choose that texture (pre-chosen as factory reset setting) when you’re shooting
with other ARRI ALEXA or AMIRA cameras simultaneously or simply if you do not
want to use the ARRI Textures feature.
Please see the separate document “ARRI Textures” for in-depth information and
sample images.
2.5 New image science and Log C
Aside from the new sensor, one of the biggest advances introduced with the
ARRI ALEXA 35 is the new image science “REVEAL”, including a number of new and
updated image processing steps. Two of these steps are the new ARRI Wide Gamut
(AWG4) color space and the new LogC4 tonal curve. The new ARRI LogC4 tonal
curve has the capability to encode the increased dynamic range of the new
sensor.
REVEAL is backwards compatible for ARRIRAW footage from ALEXA or AMIRA
cameras.
2.6 ARRI Wide Gamut 4
The AWG4 colorspace has been optimized to suit the needs of the ALEV4 sensor.
It is bigger than Rec 2020 but in the same moment not too big to reduce or
avoid virtual colors.
2.7 LogC4
Adding more dynamic range to a sensor means dealing with “more image
information” to fit into the existing pipelines. To accommodate the data from
ALEV4 it was necessary to create a new tonal curve, the LogC4 curve.
At first sight a LogC4 images is darker than a likewise well exposed LogC3
image:
LogC4 is very different from LogC3 (the Log C you are used to)! This calls for
adaption when exposing the
sensor as a single operator as well as for DITs who monitor exposure or do
live grading. LogC3 3D LUTs do
NOT work with LogC4 and may lead to unwanted results!
The nature of the new LogC4 curve is clearly visible once you plot it as a graph: Mid gray in LogC4 sits at: 1140/4095 // 285/1023 // 28%. This is lower than the 39% of LogC3 because the greater dynamic range calls for more headroom for the additional stops.
Looks & 3D LUTs for LogC4
3.1 Looks on set
Look files are a popular tool to implement one’s creative vision early on in
production. REVEAL color science brings a new version of that to the camera:
ARRI Look File 4 (ALF4). To make the look file more universal we’ve separated
the color space transform from the creative look file:
That
enables ALEXA 35 to output REC 709 (SDR) on SDI1 and e.g. REC 2100/PQ (HDR) on
SDI2. The camera handles the color space transformation. Or in post production
your tool of choice takes over that step.
ALEXA 35 ships with the ARRI Look Library in its new version “LogC4” pre-
installed. That are all looks you’re used to from ALEXA Mini and AMIRA adapted
to LogC4.
Add looks to
your “camera folder” like in ALEXA Mini or AMIRA.
As a default, there is only one standard ALF4 look
file available in camera, this is a straight passthrough/dummy without changes
to the imge.
The Look Library used to come in three flavours for different strenghts, this
has been replaced by an option in the camera to set the Look Intensity in 10%
steps from 100% (= look fully applied) to 0% (= LogC4 image).
3.2 Manual Look Creation
Of course, ALF4s can be created manually as well. As you’re used to from ALEXA
cameras, your favourite tool will certainly support the new ALF4 workflow.
We will release a combined tool for Viewing, Rendering, Metadata and Look
Files: the ARRI Reference Tool (ART). It will be compatible with ARRIRAW and
Apple ProRes clips.
3.3 Using 3D LUTs
In case you are using an external life grading solution on set any looks will
have to be created by outputting a
LogC4 signal from the camera and feeding that into a LUT box or LUT-capable
monitor, which must (also) use
our new LogC4 color space transform 3D LUTs.
The latest ARRI-offical 3D LUTs for ALEXA 35 can be found here.
3.4 3D
LUTs in post-production
For color grading ALEXA 35 footage it’s also key to use our latest ARRI-
offical 3D LUTs. This initial set of LUTs can be used in post production tools
and software that support the *.cube LUT file format. We offer different 3D
LUT files for all common color spaces e.g. Rec2020, St2084 or Rec709 Gamma
2.4.
The latest ARRI-offical 3D LUTs for ALEXA 35 can be found here.
Please note : It is most important, that all footage which has been
captured with the ARRI ALEXA 35 must be processed by using new 3D LUTs that
were especially developed for the new LogC4 tonal curve.
Older 3D LUTs that were used for ARRI LogC3 (e.g. for ALEXA, AMIRA, ALEXA
Mini, ALEXA LF and ALEXA Mini LF) should not be used for screening or post-
production workflows together with ALEXA 35 footage.
ARRI Tools
4.1 Frame Line & Lens Illumination Tool
The FLLIT has been updated for ALEXA 35.
4.2 Formats & Data Rate Calculator
FDRC has been updated for ALEXA 35.
3rdParty Support
We’re supplying the new ARRIRAW SDK 7.0.0 to solution partners all around the industry to enable ALEXA 35 support in their tools. This is an ongoing process and we’re keen to see live implementations when ALEXA 35 ships to the first customers.
Contact
In case you have a request, questions or recommendations, please contact the Digital Workflow Solutions group within ARRI via email: digitalworkflow@arri.de
ALEXA 35 Workflow