Development of a Drive Unit for a Cost-effective Follow-focus Control System

Abstract

Objectives - This study compares the most affordable stepper motors currently available for suitability as the main component of the drive unit for the development of a cost-effective Follow-focus Control System for deployment in Higher Education in photography.

Methodology - Applying a quantitative approach through a prototype design methodology the required criteria of speed, torque and accuracy were defined and the candidate stepper motors’ performance compared to a theoretical ideal to define their suitability.

Findings - A testing process that artificially simulated general, real-world, use-cases revealed that both candidates, the 28BYJ-48 stepper motor and the 17HS2408 Nema 17 stepper motor, met the required torque and speed metric of facilitating high-speed focus shifts in one second without introducing unwanted camera movement, skipping steps or introducing vibration while maintaining focus accuracy within the defined accuracy metric as determined by focus charts. Both candidates also completed low-speed focus shifts over a set period of 10 seconds to assess smoothness of the resultant focus shifts without introducing unwanted camera movement or vibration while maintaining focus accuracy within the defined accuracy metric. These results illustrated both of the candidate stepper motors met the required testing metric needed to serve as the main component of a Follow-focus control system drive unit. These finding now offer a clear and concrete departure point in discrete component for the development of a drive unit for a follow focus control system.

Application - It is recommended that the 28BYJ-48 stepper motor be deployed for the development of a cost-effective Follow-focus control system drive unit due to its lower price combined with torque and accuracy metrics that fall within the defined range of acceptable performance for industry application.