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WHAT IS LENS METADATA AND WHY SHOULD I CARE?




Many of us have been seeing a curious marking on lenses and cameras now for the better part of the last decade, and it looks like this: ‘/i’ or LDS. We understand that it has something to do with lens data and we think that it probably does something useful.

Let's start with a history lesson: it all began with a guy named Les Zellan, who had a dream to buy a little lens manufacturer in Leicester, England after touring the factory some 17 years earlier and being emotionally touched by its legacy and unfortunate impending demise. Over time he cobbled together his savings, an investor or two, a bank loan and dubbed the venture a 120-year-old ‘start-up’, with Cooke emerging as an independent company in 1998. Within the first year they released the beloved S4s, Cooke’s first new lenses in over 35 years, a system which garnered several awards, including a Technical Academy Award for mechanical and optical excellence in 1999, and a Technical Emmy in 2000.



Les and his century-old start-up were delivering a complete set of handmade Cooke S4 lenses when he simultaneously implemented his second dream: lens metadata.  In 2019, most of us understand or have some clue what metadata is, but in 1998, pre-digital camera days, metadata was a conversation best left to people in coffee shops in Silicon Valley, certainly not a handcrafted lens maker as old as time. Nevertheless, in 2000 Cooke launched /i –“intelligent” technology, and shortly after ARRI released LDS (Lens Data System), two different yet similar systems for automatically reporting precise and detailed data about lens size, focus, hyper-focal distance, depth-of-field, iris, lens model, and other pertinent information from digital or film cameras synced to timecode for use on the set or in post and VFX.

Les admits he was ahead of his time, but also laments that he didn’t think the evolution of /i would take so long to adopt - it’s something producers, cinematographers, ACs and post supervisors know they want, but sometimes do not feel they have the wherewithal to implement. Cooke has offered open sharing of the /i technology - this was something Les knew was important for it to flourish from the outset - so for a whopping 1 pound companies like ARRI, Angenieux, Canon, Panasonic, Panavision, RED, and Zeiss can add /i technology to their cameras and lenses. Additionally, a Cooke lens with or without /i ostensibly costs the same to make, meaning all future Cooke lenses will have /i technology.



Let’s take a closer look at ARRI’s LDS. In 1999 ARRI began the development of Lens Data System or LDS, based on a concept by the Oscar-winning engineer/developer of the Moviecam - Fritz Gabriel Bauer. LDS was revealed to the industry at the Cinec exhibition in 2000. Similarly to /i, ARRI’s LDS displays lens data on ARRI’s WCU (Wireless Compact Unit), in status overlays in-camera and on connected monitors.

To discover more about /i and LDS in the real world, we consulted with Snehel Patel, Director of Cinema Sales at Zeiss. According to Snehal, “Neither system is superior to the other. They are just languages that specify where sensor data is to be stored in a database. The fidelity of the data, the speed at which it is generated and the accuracy are all dependent on the hardware encoders in the lenses, the hardware, and software of the camera, and not the protocol itself.”



ON SET
Application of /i and LDS is simple - lenses and cameras equipped with either sync automatically through the corresponding data input contact crafted into the lens and camera mount and the data are stored within the metadata of the actual camera recording. Older cameras without /i or LDS technology may be coupled with lenses with an external /i or LDS port if the camera has a time code output and the data can be recorded externally to a recorder such as the Ambient Master LockIt or the Transvideo Starlight. For LDS and cameras and/or lenses without lens data built in, ARRI’s LDS works as a system to capture the metadata (via the Universal Motor Controller UMC-4A) or to open the “world of lens data” for all lenses: every lens can be trained in the LDS system and be added to the Lens Data Archive (LDA). The LDA enables us to use external lens motors to train a non-LDS lens to act like an LDS lens via generating lens data through the motor encoders.  

It is highly suggested to have a proper workflow and nomenclature agreed upon before shooting to avoid files being lost or misplaced. This data will theoretically be stored frame by frame, although to date, not all cameras record data frame accurately, which was discovered as Cooke developed i3, the next phase of /i technology and while Zeiss was developing their own expanded version of /i with Zeiss eXtended Data. Designed to provide information about the lens distortion and shading characteristics in real-time, this information is applied as part of the VFX process or anywhere it is needed.

On set the /i technology allows the focus puller to get an accurate readout from a lens on their remote focus device instantaneously, the lens information may also be displayed on an onset monitor in an easy to read format; information such as lens size, F stop, focal distance are easily accessible to supervisors of both script and VFX, therefore taking some of the tedium out of the VFX process.

Stay tuned for Part 2 of our Lens Metadata series, where we’ll examine how lens metadata is used in post-production and VFX.

Thanks to DP Jimmy Matlosz (www.dpmatlosz.com) for assistance in crafting this article.

 


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