Draft:Lens Rehousing

Lens rehousing is the process of replacing the original housing of a camera lens, often a vintage one, with a new housing. This practice is common in the film industry, where lenses are required to be durable, usable, and compatible with various camera systems. The rehousing process is intended to enhance the mechanical and optical capabilities of the lenses, adapting them for use in professional environments.

Overview
Vintage still photography lenses are often used in modern filmmaking for their distinct optical characteristics, such as bokeh, sharpness, and color rendition. However, some filmmakers have reported that the original housings of these lenses may not always meet the requirements of modern filmmaking. . Issues can include a lack of durability for regular use or incompatibility with contemporary camera mounts and accessories. Lens rehousing seeks to address these issues by transplanting the optical elements of a lens into a new, custom-designed enclosure, which is intended to enhance its functionality and extend its lifespan.

Process
The rehousing process involves several key steps
 * 1) Initial Assessment and Design: Each lens undergoes a thorough inspection to assess its optical condition. Based on this, new parts are custom-designed, reflecting the unique requirements of the lens.


 * 1) Component Machining and Preparation: The designed parts are then precision-machined, often in-house, and prepped for assembly. This includes crafting the mechanical components that will house the optical elements.


 * 1) Disassembly and Optical Servicing: The original lens is carefully disassembled, and the optical elements are serviced. This step includes cleaning and any necessary repairs to maintain the lens's optical quality.


 * 1) Reassembly and Non-Linear Cam Integration: The optical units are installed into the new chassis with an optional non-linear cam mechanism that allows for an extended focus throw and eliminates backlash, enhancing focus control.


 * 1) Engraving and Final Quality Control: Accurate focus and aperture scales are engraved onto the new housing. The lens then undergoes a final inspection to ensure it meets the high standards expected of modern cinematography equipment.

Benefits

 * Durability: The new housing is typically more durable and better suited to withstand the rigors of professional use.
 * Usability: Features like smoothly turning focus rings and standardized gear positions make the lenses easier to use, especially when pulling focus and changing aperture in a film environment.
 * Compatibility: Rehoused lenses are often designed to fit modern camera mounts and accommodate various accessories, making them more versatile.
 * Preservation: Rehousing can extend the life of rare or vintage lenses by protecting their delicate optical elements.

Industry Impact
Lens rehousing has a significant impact on the film industry. It allows cinematographers to use vintage lenses that are known for their unique aesthetic qualities, alongside modern digital camera systems. This blending of old and new technology fosters creative expression and technical innovation.

Historical Context
Lens rehousing is not a recent development; it has existed for several decades, dating back to the film era in the 1980s. Historically, many rehousing services were active and well-known within the industry, including companies like Century Optics and Moviecam. These early rehousing efforts set the stage for the sophisticated services available today, highlighting the ongoing demand for customizing and upgrading lens capabilities to meet evolving cinematographic needs.

Economic Impact
The rising popularity of rehousing vintage photography lenses has significantly influenced their market prices. For example, some Canon FD lenses, which cost less than $800 just a few years ago, have seen their prices surge to more than $20,000 due to the high demand for rehousing. This steep increase in prices has caused dissatisfaction among still photographers, who find these lenses increasingly unaffordable for traditional photography use. The shift in pricing reflects the broader impact of lens rehousing on the availability and accessibility of vintage lenses in the photography community.

Influence in High-Budget Films
Rehoused vintage lenses have also made a significant mark on high-budget Hollywood films, further driving up their demand. For instance, films such as Dune: Part Two and Army of the Dead utilized vintage rehoused lenses to achieve a distinct visual style that contributes to the cinematic narrative. The unique characteristics of these lenses, combined with modern rehousing techniques, enable filmmakers to capture specific aesthetic qualities that are challenging to replicate with modern lenses alone. The use of such lenses in prominent films has heightened interest and demand for vintage lenses, pushing their prices even higher and highlighting their value in contemporary film production.

This widespread use in major film productions not only showcases the technical capabilities of rehoused lenses but also underscores their artistic value, making them highly sought after in both the film industry and among collectors.

Differentiating Lens Rehousing from Lens Sleeving
Both lens rehousing and lens sleeving provide methods to update and adapt lenses, yet they serve different purposes and achieve varying levels of enhancement.

Lens Rehousing

 * Original Housing: Discarding all original metal parts of the lens housing, keeping only the optical element.
 * New Housing: Designing and constructing a new, robust housing often made from high-grade materials like aluminum or stainless steel.
 * Enhancements: Incorporating features such as standardized focus and aperture gear rings, and a consistent front diameter for easier attachment of filters and matte boxes.
 * Total Reconstruction: This process ensures that the lens is rebuilt from the ground up, aligning with professional standards for durability and usability.

The primary advantage of true lens rehousing is the significant improvement in both the mechanical and optical performance of the lens, making it suitable for professional filmmaking.

Lens Sleeving
Lens sleeving, contrastingly, is a less invasive modification process characterized by:
 * Original Housing: Retaining most or all of the original lens housing.
 * Additional Casing: Adding a new casing or sleeve over the existing housing, which may be for aesthetic purposes.
 * Limited Mechanical Improvement: Since the original mechanical components are kept intact, there is generally no enhancement in mechanical performance such as focus smoothness or aperture precision.
 * Focus on Adaptation and Protection: The process is primarily aimed at compatibility and protecting the original housing, rather than improving mechanical performance.

While both lens rehousing and lens sleeving adapt and extend the usability of lenses, lens rehousing offers a more extensive and beneficial modification. It ensures that lenses not only fit modern camera systems but also meet the demanding needs of professional environments through enhanced mechanical performance. Lens sleeving, though less costly and less invasive, provides limited improvements and is typically more suitable for non-professional applications where basic adaptations or cosmetic changes are the main goals.

Variability in Lens Rehousing Mechanisms
Lens rehousing can vary significantly in terms of the mechanisms used and the quality of construction. The primary mechanisms employed in lens rehousing are the cam follower mechanism and the helicoid mechanism, each bringing distinct advantages and considerations.

Cam Follower Mechanism
The cam follower mechanism is preferred by many high-end lens rehousing services due to its precision and reliability. This mechanism involves a follower pin or roller running along a specifically shaped cam groove, which controls the movement of lens elements more accurately than other mechanisms. There are numerous variants of the cam follower mechanism, each designed to meet specific performance criteria and cost considerations. These variants can differ in terms of materials used, the shape and size of the cam, the type of followers, and the assembly techniques.

An advanced feature of this mechanism is the ability to customize the cam track, which enhances focusing capabilities across the entire range. By designing the cam track to stretch the focus scale near the infinity mark, the mechanism prevents the compression of focus marks at longer distances, such as beyond 10 meters or 30 feet. Additionally, it can be configured to accelerate the movement of the lens cell at closer focus distances, ensuring that focus marks are not spaced too far apart. This dual optimization leads to a more uniform distribution of focus marks throughout the focusing range, significantly improving precision. Some advanced cam follower mechanisms also incorporate a spring-loaded feature to reduce backlash, which contributes to smoother and more precise focus adjustments. These features make lenses rehoused with cam follower mechanisms highly suitable for professional film and video production, where precise focus control is crucial for both close-up and distant shots.

Helicoid Mechanism
Conversely, the helicoid mechanism involves a threaded helical cut in the lens barrel that allows the lens elements to move in and out as the barrel is twisted. Although many vintage photography lenses also use helicoid mechanisms, modern rehoused lenses with updated helicoids can offer superior performance due to advancements in materials, precision in threading, and better engineering practices. Contemporary rehoused lenses that employ helicoid mechanisms are often more robust than their vintage counterparts, providing smoother focusing and enhanced durability, suited for professional use. However, using a helicoid mechanism does not necessarily imply inferior quality. Some high-end cine lenses, such as the Zeiss Ultra Prime, utilize helicoid mechanisms and are considered among the best in terms of mechanical performance. Differences in the design of the helicoid, such as the pitch of the threads and the material used, significantly affect both performance and cost.

Limitations and Considerations in Lens Rehousing
While lens rehousing can significantly enhance the usability and performance of vintage, not every lens is suitable for rehousing. Several factors influence whether a lens can be effectively rehoused, including its original design, economic value, and demand.

Technical Limitations
One of the primary technical limitations in lens rehousing involves the back focal distance of the lens. Lenses designed for rangefinder cameras or cameras without mirrors, including most X-ray lenses with super fast apertures, have very short back focal distances/lengths. These lenses are designed to have their rear elements very close to the sensor/film plane, which can make it challenging to rehouse them into standard mounts like PL mount. However, rehousing into an LPL mount might be possible in some cases due to its shallower flange depth offering slightly more flexibility for these types of lenses.

Economic Considerations
Not every lens is considered a viable candidate for rehousing, as the investment required may not always be justified. Factors such as market demand, resale value, and the overall cost of rehousing can influence whether a particular lens is deemed economically feasible to rehouse. Lenses with lower market demand or resale value might not generate sufficient returns to recover the rehousing costs, making them less attractive options for rehousing services. Conversely, lenses that are in higher demand, often due to desirable features such as fast apertures or unique optical characteristics, are generally seen as more suitable candidates for rehousing. The potential financial viability of rehousing these lenses is typically higher, as the investment is more likely to be justified by the market demand and resale value.

Service Provider Constraints
Rehousing a lens requires significant time, effort, and resources from the service provider. The process often involves custom-designing new mechanical parts and recalibrating optical elements to ensure enhanced performance and compatibility with modern camera systems. Due to these demands, many rehousing services are selective about the lenses they choose to work on. They typically opt for projects that promise a clear economic benefit—either through high demand or because the lens itself offers superior optical qualities. If a project is unlikely to be economically viable, a service provider might decline it as it wouldn't sufficiently compensate for the labor and costs involved.

Lens Rehousing Service Providers
The lens rehousing industry is served by a variety of service providers across the globe, each offering different capabilities and services. As of April 2024, it's generally recognized within the industry that there are approximately eleven lens rehousing companies worldwide. These companies are known to differ in the scope of their services, pricing, mechanisms used, and lead times.


 * TLS (True Lens Service) - UK
 * G.L Optics - China
 * P+S Technik - Germany
 * Zero Optik - USA
 * Whitepoint Optics - Finland
 * Kimcamera - South Korea
 * Iron Glass - Ukraine
 * Eastern Enterprises - Japan
 * Gecko Cam - Germany
 * Mirrorscope - Australia
 * TK LENSES - Thailand

Variability in Services
The service levels and pricing among these providers vary significantly. The cost of lens rehousing can range from approximately $1,600 to $6,000   depending on the service provider. Higher-end services often provide more robust and reliable quality rehoused lenses. These premium services are likely to include advanced mechanisms that minimize common issues such as backlash, image shift, or inaccuracies in focus and iris scales.

Conversely, lower-end services, while more affordable, may suffer from lower-quality construction and less reliability. These might manifest as mechanical issues like de-centering, backlash, image shift during focusing, or inaccurate calibration of focus and iris scales.

Lead Times
Lead times for rehousing projects also differ significantly, ranging from as short as nine months to as long as three years depending on the provider's backlog and the specific requirements of the rehousing project. Additionally, some providers may offer already rehoused lenses for sale, which can be a faster alternative to waiting for a custom rehousing job. However, these pre-rehoused lenses are usually priced higher, and the quality of the donor optics is predetermined, as the lenses have already been chosen and rehoused by the provider. This option might not suit those who wish to select specific lenses for rehousing based on personal preference or specific optical characteristics.

Legacy of Past Providers
The current landscape of lens rehousing has been influenced by the work of earlier providers, some of which are no longer in operation, including:
 * Moviecam - Austria
 * Century Optics - US
 * Van Diemen Optics - UK