Kit tool
Lens filter size planner
Add your lenses and the filters you own. The planner finds the size that fits everything with step-up rings, and says which filters fit directly.
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3 lenses for the EOS R50
Buy 55 mm filters
They fit RF-S55-210mm F5-7.1 IS STM directly, and the rest through 2 step-up rings.
- RF-S10-18mm F4.5-6.3 IS STM: 49–55 mm step-up ring 49–55 mm ring on Amazon
- RF-S18-45mm F4.5-6.3 IS STM: 49–55 mm step-up ring 49–55 mm ring on Amazon
| Lens | Thread | Your 55 mm |
|---|---|---|
| Canon RF-S10-18mm F4.5-6.3 IS STM | 49 mm | With a 49–55 mm ring |
| Canon RF-S18-45mm F4.5-6.3 IS STM | 49 mm | With a 49–55 mm ring |
| Canon RF-S55-210mm F5-7.1 IS STM | 55 mm | Fits directly |
How step-up rings work
A step-up ring screws into a smaller lens thread and takes a larger filter, so one set of filters fits several lenses. Rings only go up: a filter smaller than the lens thread would darken the corners. With a ring fitted, the lens's own hood usually will not fit, and a cap needs the filter's size.
Facts checked 9 Oct 2026 against the makers' specification pages. How we check