ARRI ALEXA 35 Body & PL Mount Set (LBUS) - Manual (Page 91)

Lens & Electronic Control System (ECS) 91
22 Lens & Electronic Control System (ECS)
22.1 Lens Data
ARRI Lens Data System (LDS)
The Lens Data System (LDS) allows ARRI cameras and accessories to identify connected lenses and
exchange dynamic lens data reflecting the current lens settings. It works with cine lenses using ARRI
LDS or LDS-2 technology, lenses using Cooke /i technology and even cine lenses without lens data
capabilities. LDS also offers basic support for most B4 or PL ENG lenses and Canon photo lenses
when used with the appropriate mount. Available lens information can be displayed live on lens control
units like the Hi-5 or WCU-4, in the camera’s viewfinder and on the monitoring outputs. It is sent with
very low latency via Ethernet for use in mixed reality/virtual production environments and embedded as
ancillary data in the SDI output. Post production benefits from frame accurate dynamic (per frame) and
static (per clip) lens data in all original camera files.
Lenses with ARRI LDS Technology
Most ARRI lenses following the ARRI/Zeiss Ultra Prime LDS have built-in LDS functionality. This offers
basic lens information and accurate lens tables for the Focus, Iris, and Zoom axis (if applicable). LDS
lenses have integrated encoders for each axis and therefore deliver lens metadata even if the lens is
adjusted manually. LDS-2 is the latest generation of the lens data system. It was introduced with the
LPL mount and ARRI Signature Prime and Signature Zoom lenses. LDS-2 offers more bandwidth,
higher precision and faster communication. LDS-2 requires no calibration turn to the end stops of each
lens ring to deliver data. LDS-2 is prepared for future applications and is being licensed to other lens
and camera manufacturers.
Lenses with Cooke /i Technology
Many lenses, camera and lens control system manufacturers rely on /i Technology, which has been
designed and developed by Cooke Optics as an open lens metadata protocol. Every ALEXA camera
with an LDS capable lens mount, including the original ALEXA “Classic”, supports basic /i Technology.
Please note that some older Cooke lenses may be running on outdated firmware. This is likely to
cause incompatibilities with the LDS. Please contact Cooke Optics directly for more information about
checking the lens firmware version and available updates.
Lenses without Lens Data Capabilities
To get the FIZ information for a lens without lens data capabilities, the LDS can derive the lens ring
positions based on end-to-end calibrated lens motor positions and a lens file that is used as a look up
table. These files are available from the Lens Data Archive (LDA), a local library of lens files, which can
also be extended by the user. The LDA exists in ARRI cameras or accessories like the UMC-4, RIA-1,
or cforce mini RF or in the ECS sync app for iOS.
To create a new lens file, you need a camera, lens motors, a HI-5 or WCU-4 wireless lens control unit
and the lens. First, the motors are calibrated to the end stops of their lens rings. Then, axis by axis,
the lens control is used to drive the lens to each marking on the lens barrel and to set markers for the
corresponding motor (encoder) position. Finally, the lens file can be stored by e.g. model, focal length
and optionally lens serial number. Programming a lens file takes a while, but is time well spent, as it can
be shared between LDAs and therefore only needs to be done once.
ARRI Lens Data Mount
Certain non-LDS lenses can be retrofit with an ARRI Lens Data Mount (LDM-2), which is programmed
with the lens file. Using a Lens Data Mount instead of the LDA is more practical where one lens may be
used on many cameras, such as a camera rental operation. It also saves time in production as the LDS
automatically uses the file when the lens is attached.
The LDM-2 is available for Angénieux Optimo 24-290, Angénieux 17-102, Angénieux 25-250, Cooke
25-250, Cooke 18-100 and Zeiss Apo Tessar 300.