In modern film and television production, accurate lens metadata has become essential infrastructure for VFX-heavy workflows. Focus, iris, and zoom (FIZ) data enables post-production teams to match virtual elements precisely to live-action footage, dramatically accelerating compositing work and improving final image quality. However, there’s a fundamental principle that every DIT and VFX supervisor should understand: bad data is worse than no data. Inaccurate metadata creates false confidence in the pipeline and wastes valuable artist time troubleshooting discrepancies.
Two primary methodologies exist for capturing lens data during production: injection recording and sidecar recording. Each serves distinct purposes within the broader production ecosystem, and understanding when to use each approach can significantly impact post-production efficiency.
Understanding Injection Recording
Injection recording embeds frame-by-frame lens metadata directly into camera RAW files as they’re being recorded. This happens through real-time communication between the lens encoding system and the camera body, utilising the underlying network communication layer to write metadata alongside image data.
The advantages of injection are substantial. Because metadata and image data are captured simultaneously in the same file, frame synchronisation is automatic and guaranteed. The metadata travels with the image throughout the post-production pipeline, eliminating the need for separate file management or manual synchronisation steps. This streamlined workflow reduces risk of sync errors and significantly decreases the workload for DITs and the dailies team.
Multiple pathways to injection exist depending on camera and lens packages. Smart lenses with built-in encoders—such as Cooke /i technology or ZEISS eXtended Data—inject metadata directly into compatible cameras without requiring any external hardware. The lens itself contains the encoding technology, making it genuinely plug-and-play for productions using these optical systems.
For ARRI ALEXA cameras, when the first AC uses a WCU-4 or Hi-5 handset, lens data embeds automatically through the handset system itself. This native integration means productions using ARRI’s wireless ecosystem already have injection capability without additional equipment.
When working with non-smart lenses or camera systems requiring external encoding, dedicated hardware provides the injection pathway. For the ARRI ALEXA family, systems like the LDT-A2 and LDT-M2 connect via LBUS and CLM ports on the camera body. For RED cameras, Sony Venice/Venice 2, and Panavision DXL systems, the LDT-R2 and LDT-V2 connect through camera control ports to provide frame-accurate metadata injection.
It’s important to understand that external encoding systems aren’t plug-and-play solutions. They require lens mapping—a process that takes approximately five minutes per lens to create a digital profile of each lens’s focus, iris, and zoom characteristics. This mapping must be done as early as possible during prep to allow sufficient time to process the entire lens package. The lens mapping guide provides detailed technical information on this process.
Understanding Sidecar Recording
Sidecar recording takes a fundamentally different approach: lens data is written to separate CSV files on SD cards within the encoding unit, rather than embedded into the camera files. These sidecar files must then be synchronised with the footage during post-production.
This methodology becomes necessary in several scenarios. Film cameras—including ARRIFLEX, ARRICAM, Panavision XL2, and all other celluloid-based systems—cannot accept injection recording because there’s no digital file to embed metadata into. The fundamental nature of shooting on film means sidecar recording is the only option for capturing lens data.
Digital cameras without native metadata capability also require sidecar recording. Some camera systems simply don’t support lens data injection, regardless of external hardware availability. Additionally, port unavailability can necessitate sidecar recording even on otherwise capable cameras—if the required control port is already occupied by another critical system, injection may not be technically feasible.
The sidecar workflow operates by writing frame-by-frame data to a microSD card in the encoding unit. This requires both an external timecode source fed to the encoding unit and a visual timecode slate captured in every take. The visual slate provides a human-verifiable reference point for synchronisation, whilst the timecode creates the technical sync point for the sidecar CSV files.
Daily QC of sidecar files is essential—someone must verify files record correctly, timecode is consistent, and no gaps exist. This daily validation ensures problems are caught immediately rather than discovered weeks later when footage reaches the pulls house.
The challenges of sidecar recording are primarily organisational. Coordination between camera recording and sidecar recording must be precise. File management protocols need to be robust—each day’s sidecar files must be properly backed up, labelled, and tracked alongside the camera media. In post-production, the pulls house or VFX prep team performs manual synchronisation, matching the CSV files to the processed footage using the timecode reference. This adds labour and QC steps compared to injection workflows, but it remains a proven, reliable methodology when injection isn’t available.
Hardware solutions for sidecar recording include the LDT-F1, which is purpose-built for film cameras, and the LDT-R2, which offers internal recording mode for digital cameras requiring sidecar methodology.
Validation Overlays in Practice
Validation overlays provide real-time on-screen display of lens data and camera information, serving dual purposes throughout production. For VFX teams and DITs, overlays offer immediate visual confirmation that the correct lens is loaded and data is flowing accurately. Digital cameras typically provide overlay capability through their monitoring outputs, whilst the VFX crew can verify lens selection and metadata from their monitoring position, streamlining communication on busy sets.
For film productions, the LDT-F1 provides something particularly valuable: digital overlays on an analogue set. As the only device on the market that creates digital overlays for film cameras, the F1 displays camera start/stop status, footage counter information, and applies anamorphic desqueeze for proper framing on standard monitors. Custom framelines can be overlaid to show different aspect ratios or VFX plates, giving the entire crew visual references that wouldn’t otherwise exist when shooting celluloid.
The value of reliable sidecar data was demonstrated on Jurassic World Rebirth, which used the LDT-F1 to capture lens data throughout production on film. The production faced a compressed post-production schedule—just one year from filming to release despite numerous VFX-heavy sequences. The accurate lens data from the sidecar workflow helped accelerate post-production by providing VFX vendors with precise lens information from day one.
Post-Production Pipeline Considerations
The choice between injection and sidecar significantly impacts post-production workflow. Injection workflows benefit from direct metadata extraction from camera files using manufacturer-provided tools. RED footage uses REDLine or REDCINE-X Pro for extraction, whilst Sony Venice requires Sony RAW Viewer. ARRI embeds metadata directly in ARRIRAW files, accessible through standard post-production tools. Once extracted, the metadata hands off cleanly to VFX vendors as part of the standard deliverable package.
Sidecar workflows require additional steps. The CSV files from the SD cards must be matched to footage using timecode as the sync reference. The pulls house merges sidecar data with scanned or transcoded footage, creating a unified deliverable with embedded metadata. An additional QC step verifies synchronisation accuracy before delivery to vendors. This process is more labour-intensive but represents a well-established workflow that major films have relied upon for years.
The smart lens ecosystem offers an elegant injection solution when optical requirements align with production needs. Cooke /i and ZEISS eXtended Data lenses inject metadata without external encoding hardware. Whilst lens selection is rightfully driven primarily by optical quality and artistic requirements, when productions choose smart lenses for their imaging characteristics, the built-in lens data capability is a welcome benefit for the post-production team.
Production Planning and Testing
Early preparation proves critical for successful lens data capture. Lens mapping for external encoding systems must happen as early as possible during prep, allowing sufficient time to process the complete lens package. Discussing the specific camera package, lens selection, and post-production requirements with equipment providers and post facilities helps identify the optimal recording methodology and any potential technical constraints.
Testing the complete pipeline from capture through post-production establishes ground truth before principal photography begins. These tests validate hardware setup and data accuracy, confirm the post-production workflow functions correctly, and catch potential issues when there’s still time to resolve them. A comprehensive approach to round trip testing—covering the complete validation process from camera through final deliverables—is explored in depth in a companion article.
Making the Right Choice
Production requirements should drive the methodology decision. Choose injection when the camera system supports it—either natively through smart lenses or ARRI handsets, or via external encoding hardware. Injection becomes especially valuable when streamlined workflow is a priority or when post-production timelines are compressed.
Choose sidecar recording when working with film cameras, as it’s the only available option. Digital cameras without injection capability, situations where required camera ports are unavailable, or specific system limitations also necessitate sidecar methodology. The key principle remains straightforward: use injection whenever technically possible to reduce post-production workload, but understand that sidecar recording is a robust, time-tested methodology that delivers excellent results when injection isn’t available.
Conclusion
Both injection and sidecar methodologies serve essential roles in modern production. Injection recording reduces manual labour and eliminates synchronisation risk but isn’t universally available across all camera systems. Sidecar recording remains critical for film cameras and certain digital workflows—when it’s the only option, it’s a proven solution that has supported countless productions.
The methodology matters far less than the commitment to capturing that data correctly. Proper planning during prep, rigorous testing before principal photography, and robust validation throughout production ensure excellent lens data reaches VFX and post-production teams regardless of recording method.
DCS supports productions from pre-production consultation through delivery, providing both hardware solutions and expertise to ensure reliable lens data capture. Technical documentation and detailed setup guides are available at support.dcs.film.