Building and sourcing eyepiece taps for video assist on film cameras

Gear

ZephyrCan I fly my Alexa or RED on a Zephyr?389

Master SeriesIs a used Master Series rig worth buying as a first big rig?191

BFDHow do I power my BFD receiver from my camera or sled?186

VoltCan I retrofit a Volt onto my existing sled or gimbal?168

ArtemisHow do I power my camera and accessories from an Artemis sled?166

MDRWhere can I mount my Preston MDR on my rig?143

ModulusIs there a Modulus option for HD wireless video?141

G-70Will my G-70 fit my vest, gimbal or sled?126

FI+ZCan I control iris and zoom wirelessly, not just focus?60

HU3Where can I get my HU3 repaired, refurbished or repainted?60

CineLiveHow do I pack and case my CineLive rig for transport?54

G-70XHow does the G-70X compare to Pro Titan, Xarm and other arms?46

Trinity 2Is Trinity 2 SUP 3.0 firmware safe to install or buggy?46

Ultra VestWhich vest should I choose for my body size, comfort and operator type?39

2004Video Assist and Video Accessories forum

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

Eyepiece taps can be constructed from a 24mm C-mount lens paired with an extender to achieve the required macro focus distance of approximately 1 inch from the front element.
The CCD sensor array must be positioned away from the lens using the extender to reach the proper focus distance for eyepiece tap operation.
A machined gear is necessary to interface with the eyepiece mount thread, which varies between camera models such as double helix on older Arri models and triple helix on newer ones.
Alternative DIY mounting can use aluminum strips attached to the lens secured with hose clamps to the eyepiece assembly after removing the eyecup optics.
Pre-made tap systems like those from PCI or JAR manufacturers are commercially available but designed for specific sensor sizes like 2/3 inch cameras.
Optical adapters can be sourced through scientific supply catalogs like Edmund to convert between different CCD sensor sizes on existing tap systems.
Rental houses may supply stainless steel flanges from various camera models that can be adapted for eyepiece tap construction, though this approach remains expensive.
Used eyepiece tap systems appear on secondary markets with significant cost savings compared to new equipment.
Building a functional eyepiece tap requires investment in optics, metalworking tools, and precision alignment, with success not guaranteed.

This discussion is from 2004 and reflects equipment and pricing of that era.
The DIY construction method described requires significant metalworking and optical expertise.
Compatibility varies by camera model and CCD sensor size, requiring case-by-case adaptation.
No consensus reached on whether DIY construction represents genuine cost savings versus commercial options.
Specific pricing and product availability mentioned are historical and likely outdated.