For decades, telephoto zoom lenses were divided into two categories. Budget-friendly consumer models were reasonably compact and tended to have a maximum aperture of f/4-5.6 as you stretch through the zoom range. Professional lenses were bigger, heavier, had higher-grade optics and usually boast a faster maximum aperture of f/2.8 or f/4. The maximum aperture also remains fixed throughout the zoom range, earning them the ‘constant-aperture’ moniker. The Canon EF 70-300mm f/4-5.6L IS USM broke the mold - offering a half-way house between the two types.
Despite having a fairly modest filter diameter of 67mm, 10mm less than the fast Canon EF 70-200mm f/2.8 L IS II USM lens, the lens barrel is almost the same width. At first the 70-300mm L looks like a budget telephoto zoom packed into an oversized full metal jacket. Look deeper, though, and you’ll find a full raft of Luxury-series finery. Build quality feels rock solid, there’s full environmental sealing to guard against moisture and dust in adverse shooting conditions, and all switches and moving parts feel of fully professional quality.
