Budget Canon telephoto zoom, cheap but optically weak and widely bundled with entry DSLRs.
The Canon EF 75-300mm f/4-5.6 III is Canon's entry-level consumer telephoto zoom, introduced in 1999 and bundled with Rebel-series and EOS xxxD cameras for over a decade. On full-frame it covers 75-300mm; on APS-C bodies the 120-480mm equivalent made it many buyers' first telephoto experience. The optical formula uses 13 elements in 9 groups. No image stabilisation is provided. Autofocus uses a DC micro-motor — giving the lens its III rather than USM designation — which is slower and noisier than Canon's ring-type USM designs. At approximately 480g with a 58mm filter thread and an all-plastic construction including the mount, it is a lightweight but optically limited telephoto for casual use.
The lens performs acceptably at 75-150mm stopped down but deteriorates noticeably above 200mm. At 300mm sharpness falls off significantly across the frame, chromatic aberration is prominent in high-contrast subjects, and field curvature reduces consistency. There is no stabilisation to compensate for the long focal length: a minimum shutter speed of 1/400s is necessary for consistent handheld results at 300mm, which limits its utility in marginal light. Autofocus is adequate in bright, high-contrast conditions but hunts in lower light or against plain backgrounds. The DC motor is audibly noisier than USM alternatives. The EF-S 55-250mm IS STM is sharper across the range with stabilisation on APS-C bodies.
EF mount only, 58mm filter thread. The barrel extends significantly at 300mm — roughly double its collapsed length — and the extended barrel shows some play in use, typical for this construction class. No weather sealing. Full-time manual focus override is not available with the DC motor; AF must be disengaged to use the manual focus ring. Compatible with all EF-mount Canon bodies including full-frame. The slip-on ET-60 lens hood is a standard accessory frequently missing on used copies.
The EF 75-300mm III sits at the very bottom of Canon's telephoto range and prices reflect this. For APS-C users, the Canon EF-S 55-250mm f/4-5.6 IS STM is a sharper lens across the range with image stabilisation and should be preferred when available. For full-frame users needing a low-cost telephoto, the EF 70-200mm f/4L non-IS (used) provides far superior optics at a modest premium. At this price point, repair cost exceeds the lens value, so confirm AF responds without hesitation before purchase. Test sharpness at 300mm to establish the specific copy's optical condition.