I got a few projects coming up for which I want to rent a set of old C-mount Kern Switar lenses (the 10mm, 25mm, and 75mm, and the older versions without the focusing handle to be exact)from my local rental house. As much as I adore the look of these lenses on a modern super 16 sensor, I always assumed that they would be very challenging to use given their tiny form factor and lack of the little handle for focusing some of the modern multi-coated versions have. To my un-surprise, I went down to the rental house and tried the lenses for myself and found the handling to be difficult (for me at least with my fat fingers) to get a good focus throw without being awkward readjusting. Ideally I'd add a follow focus to the lenses, but I haven't been able to find gears, 3D printed or otherwise, that I could get my hands on.

I wanted to see if anyone had ideas for how I could get a better grip on the lenses, whether that be focus gears or a handle or something, as long as it doesn't modify the lens itself on account of it being a rental. Has anyone used these lenses successfully?