Canon's original 300mm f/2.8L super-telephoto with IS stabilisation — first generation with ring USM AF.
The Canon EF 300mm f/2.8L IS USM was released in 1999 as Canon's constant f/2.8 super-telephoto prime, incorporating one fluorite and two UD elements for minimised chromatic aberration at wide apertures. IS provides approximately 2 stops of handheld stabilisation. The front element design does not accept standard screw-in filters — instead, a 52mm drop-in rear filter slot provides ND, circular polariser, and colour filter access. L-series dust and moisture sealing is built throughout.
The optical design uses 17 elements in 13 groups, including one fluorite and two UD elements. Eight aperture blades. No front filter thread — a 52mm drop-in rear filter system is the intended filter path. At 2,550g the lens requires a monopod or tripod for extended sessions. Minimum focus distance of 2.5m. IS provides approximately 2 stops of compensation. Ring USM provides fast, quiet AF with full-time manual override. f/2.8 maximum aperture.
The f/2.8 at 300mm on full-frame provides the fastest shutter speeds available at super-telephoto distances — practical for wildlife action, sports in variable light, and dawn/dusk outdoor photography where f/4 or f/5.6 primes cannot maintain adequate shutter speed. The drop-in filter system enables ND filter use for long-exposure wildlife with neutral density, and circular polarisers for outdoor scenes — a capability that the front-element filter design on shorter primes provides with standard screw-in filters.
On the used market the EF 300mm f/2.8L IS USM is available at established super-telephoto prime pricing, significantly below the current IS III. Condition checks: IS engagement (approximately 2 stops vs IS III's 4 stops), ring USM AF response, L-series sealing, drop-in filter slot condition, and front element through the hood. The IS II (2010) and IS III (2018) provide stronger IS at higher prices. Compatible with all Canon EOS DSLR and R bodies via EF-RF adapter.