Working with digital cinema and motion-control has given me an appreciation for Cine Lenses With Gearing On Them. Working in a reality where things cost money keeps me appreciating Stills Lenses With No Gearing But With Less Numbers On The Price Tag. Adding gears to stills lenses has traditionally required relatively expensive/invasive modifications, or compromised solutions involving bolts, cable ties, or other fiddly things.
Last year I figured out how to generate arbitrarily-sized gears for my selection of lenses, changing the internal diameter of each gear by 0.5mm at a time until they fit each lens perfectly.
All the while thinking, “if someone went through this process for a wide range of diameters and shared the designs, everyone’s lenses will get better, forever!”
My process was time consuming though, with multiple steps in multiple programs required for each size. Not conducive to creating hundreds of models that weren’t directly useful to me. Eventually though, the right confluence of technologies seeped into my brain, and I taught myself enough OpenSCAD (“The Programmer’s Solid 3D CAD Modeller”) to build off an existing script to create gears designed specifically for follow focus systems.
Behold! Lens Gear for Follow Focus – Seamless Friction Fit for Lenses 50-100mm diameter and beyond on Thingiverse!
The project page has detailed instructions on measuring lenses and printing appropriate sized rings. If your lenses have protruding bits, I’ve come up with a solution using split spacers to let an appropriately sized gear ring fit over the sticking out bits, but I’ve been manually creating the spacers thus far. It shouldn’t be too time-consuming to release an OpenSCAD script to make spacers though, if you’re interested, get in touch.