Standardized lens naming protocol for Preston HU3 follow focus hand unit database

2007Follow Focus forum

19 years old. Gear and prices may have changed since.

DisputedParticipants disagreed and reached no conclusion. Read the findings as positions, not as an answer.

Hand-assembled cinema lenses have 2-3% physical travel discrepancy from lens to lens even within the same focal length, requiring individual calibration to the hard stop marks on each barrel.
The HU3 system allows calibration by selecting six reference marks that establish accurate spacing of hard marks relative to marking rings, eliminating the need to physically mark focus rings like on the HU2.
Proposed lens database would allow focus pullers to download pre-calibrated lens profiles to their hand unit by serial number, saving setup time on future productions.
Shared lens profiles can only be used after verification on set, as variations between hand units and camera systems may require adjustment to witness marks.
Close-focus lens designs have inconsistent high-speed focus behavior not only across focal lengths but between individual lenses of the same series, complicating database standardization.
Scrolling through database lists to retrieve lens data can take longer than manually installing and calibrating a focus ring, reducing practical efficiency on set.
A naming formula incorporating manufacturer code, lens type, focal length, and last digits of serial number enables consistent cataloging (example: PV-PS-40-XXX for Panavision Primo spherical 40mm).
Database effectiveness depends on field users consistently uploading calibration data after each job, with low participation rates likely limiting practical usefulness.

Proposal is theoretical and database had not yet been built at time of discussion.
HU3 computer interface required Windows operating system only, limiting accessibility for Mac-using operators at that time.
Different Preston hand units may produce different calibration results on the same lens, potentially limiting cross-unit database transferability.
Lens calibration changes after lens overhaul or repair, requiring database updates.
Anamorphic versus spherical variants, 16mm versus 35mm optics, and proprietary manufacturer catalog numbering complicate naming protocol standardization.
Some experienced focus pullers questioned whether database efficiency gains justified the workflow complexity of searching and downloading versus manual calibration.