Canon's L-series telephoto zoom with IS — professional build and optics in the 70-300mm range.
The Canon EF 70-300mm f/4-5.6L IS USM was released in 2010 as the L-series telephoto zoom, providing professional telephoto coverage from 70mm to 300mm with 4-stop IS and ring USM autofocus. At 1,050g and 67mm filter thread it is the L-series professional benchmark in this range. Dust- and moisture-resistant sealing throughout. Two UD ultra-low dispersion elements.
The optical design uses 19 elements in 14 groups including 2 UD elements. Nine aperture blades. The 67mm filter thread differentiates it from the non-L 70-300mm IS USM which uses 58mm. At 1,050g the lens is substantial. Minimum focus distance of 1.2m (maximum magnification 0.25x). 4-stop IS with tripod- and monopod-detection. Ring USM with full-time manual focus override. L-series dust- and moisture-resistant sealing.
The L-series designation brings meaningful practical improvements over the consumer 70-300mm IS USM: ring USM versus micro USM (faster, quieter, full-time manual override), 4-stop IS (versus 4-stop in consumer but with tripod-sensing in the L), L-series environmental sealing, and 2 UD elements for chromatic aberration control at 300mm. For wildlife, sports, and event photographers who need confident telephoto performance in variable weather, the L-series sealing is the primary differentiator.
On the used market the Canon EF 70-300mm f/4-5.6L IS USM is available at established L-series telephoto zoom pricing. Condition checks: IS engagement, ring USM AF response, L-series sealing, and 67mm front element for marks. The 67mm filter thread (not 58mm) confirms the L-series version. Compatible with all Canon EOS EF and EF-S bodies; on RF bodies via EF-RF adapter.