B&H Photo has a great deal on Tilta Focus Ring Gears for $2 each. I ordered a set that covers all of our lenses. To get decent measurements, I ordered a digital caliper from Amazon and measured all of my lenses. I’m not exactly sure how accurate this thing is, but the sizes that I ordered fit very well. For a few I opted to use a gear slightly smaller, seems to have worked out pretty well. Here are the measurements for our lenses, the size of the rings I ordered, and links to B&H.
| Fujifilm XF Lens | Focus Ring Diameter | Tilta Focus Gear Ring Size |
|---|---|---|
| XF 18-55mm f/2.8-4 R LM OIS | 64.9mm | 62.5-64.5mm B&H |
| XF 16-55mm f/2.8 LM WR | 77.2mm | 75-77mm B&H |
| XF 50-140mm f/2.8 LM OIS WR | 80.4mm | 78-80mm B&H |
| XF 18-135mm f/3.5-5.6 R LM OIS WR | 75.2mm | 75-77mm B&H |
| XF 35mm f/2 R | 53.7mm | 53-55mm B&H |
| XF 23mm f/2 R | 53.7mm | 53-55mm B&H |
| XF 60mm f/2.4 R Macro | 64mm | 62.5-64.5mm B&H |
I’d assume that the 50mm and 16mm f/2 share the same 53.7mm diameter as the 23 and 35 f/2, but I don’t own either of those quite yet. I’ll keep this updated if I acquire or borrow lenses to measure.