Canon's early L-series telephoto zoom — the EF 100-300mm f/5.6L from the original EF lineup.
The Canon EF 100-300mm f/5.6L is an early L-series telephoto zoom from Canon's original EF mount lineup, released in 1987. The L designation indicates Canon's professional optical tier with fluorite or UD elements. Despite the slow f/5.6 aperture, the L-series optical quality was superior to consumer telephoto zooms of the era.
Optical performance is good for the era — the L designation ensures quality above consumer alternatives. Sharpness is respectable throughout the range. The slow f/5.6 aperture limits the lens to bright conditions or high ISO. The fluorite or UD elements provide better chromatic aberration control than non-L alternatives. AF is driven by an early ring-type USM motor.
Canon EF mount, full-frame. Filter thread is 58mm — compact. Weight is approximately 540 grams — light for an L-series telephoto. Build quality is solid L-series grade with weather resistance. The early ring-type USM motor provides fast, quiet AF with full-time manual override — a significant advantage over the era's micro-motor alternatives.
Available at low used prices — the slow aperture and age have reduced demand. Check USM motor and clean optics. An interesting piece of early Canon EF/L history. The L-series optical quality remains visible. The slow f/5.6 limits practical utility. Modern alternatives are dramatically better in every measurable way.