Return Policy. Shop the EF 25 II Extension Tube from Canon U.S.A., Inc. The Extension Tube EF 25 II is recommended for lenses with a focal length of 50mm and up. This updated version II is now also fully compatible with Canon Digital EF-S lenses, as well as standard photo EF and TS-E lenses. Extension Tube EF 25 II is recommended for lenses with a focal length of 50mm and up (EF-S 18-55mm can be used at middle and tele zoom settings). Shortens focusing distance of lens Canon EF 25 II Extension Tube MPN: 9199A001 (0x) Key Features. Lens Type: extension tube SLR Canon Extension Tube EF 25 II (USED) $59.99. Add to Cart. u7KUE.