Canon EF 75-300mm f/4-5.6 III

Canon built this to fill the cheapest corner of the EOS lineup. By 1999 the Rebel film bodies were selling to first-time SLR buyers who wanted reach without spending L-glass money, and the 75-300 III was the answer Canon could bundle for almost nothing. It traced back to the original EF 75-300mm f/4-5.6 from 1991, refined across two revisions into something among the cheapest and most plastic telephoto zooms Canon ever sold. That is its entire reason for existing. It put 300mm in the hands of people who could not justify a 70-200.

Optically it shows exactly where the money was not spent. Wide open it is soft, and it gets softer the longer you zoom. At 75mm and f/4 in good light it is perfectly usable. At 300mm and f/5.6 it goes hazy, with visible chromatic aberration fringing the high-contrast edges and contrast that drops off a cliff. Stop down to f/8 or f/11 and the center tightens up to something respectable, but the corners never fully come around. The bokeh is unremarkable, neither buttery nor harsh, just background that happens to be out of focus. Flare control is weak; shoot toward the sun without a hood and the whole frame washes out.

The plain III uses a DC micromotor for autofocus, which is slow and audible, and it hunts in low light. There is a III USM variant that swaps in a Micro USM motor for somewhat quicker and quieter focus, but it is still the budget motor, not the ring-type USM from Canon's better lenses, so you do not get full-time manual focus. Neither version has image stabilization. At 300mm handheld that omission is the real limitation. You need fast shutter speeds or a tripod, and on a dim day the f/5.6 long end fights you on both counts.

Who actually shoots it: beginners, casual wildlife and sports parents at a Little League fence, and film shooters who found one in a thrift bin for the price of a sandwich. It still sells used for next to nothing, and that is the whole pitch. People cross-shop it against the Tamron 70-300 and Canon's own 55-250 on crop bodies, both of which are sharper. Nobody buys this lens for image quality. They buy it because it costs less than a roll-and-develop habit.

If you do put it on a film body for landscape or daylight wildlife, treat the 58mm front thread as your real control surface. A polarizer cuts the haze this lens already struggles to fight, and a screw-in ND lets you open up in bright sun. Meter the scene with Zone Light Meter and set exposure off that reading rather than trusting a finder that goes dark at the long end, because at 300mm and f/5.6 the viewfinder is too dim to judge by eye. Expose for the shadows, stop down to f/8, and this cheap lens behaves better than its reputation.