Canon EF 24-105mm f/4L IS USM

Cross-shop this against the 24-70mm f/2.8L and you have the oldest argument in the Canon system. The 24-70 wins on a stop of light and corner sharpness; the 24-105 wins on range and the IS unit, and it costs less. For most people who actually carry a camera all day instead of writing about one, the 24-105 wins the argument it cares about. You get from a tight interior to a head-and-shoulders portrait without changing glass, and the stabilizer buys you handheld frames at a 30th of a second that the f/2.8 cannot match in the dark.

Optically it is the honest workhorse, not the showpiece. Stop it to f/8 and the center is excellent across the whole zoom range, with corners that clean up nicely by f/11. Wide open at f/4 the center holds but the edges go soft, particularly at 24mm where there is barrel distortion you can see on a brick wall and vignetting that wants a software profile. At the long end you trade some sharpness for the reach. The rendering is neutral and contrasty in a way that suits the L color signature, and the bokeh is fine without being a selling point. At f/4 you are not buying this lens to obliterate backgrounds. You are buying it to keep the whole scene usable.

This is the lens that shipped as a kit on a generation of 5D bodies, and that is exactly the work it does best. Travel, events, editorial reportage, real estate, the kind of shooting where missing the moment to swap a 50 and an 85 is the real failure mode. Documentary and wedding shooters lived on it for years precisely because one lens covered the run-and-gun coverage and the IS saved the dim-reception frames. It is a generalist, and it knows it.

The honest weakness is the distortion and falloff at 24mm wide open. Uncorrected, the wide end looks soft in the corners and bows straight lines, and at f/4 it is dark enough at the edges that you notice on skies and white walls. Newer mirrorless RF designs lean on in-camera correction to hide this; on a film body or in raw with the profile off, you see the optical truth. It is the price of the zoom range.

A note for the film shooters, since this thread is 77mm and that opens up the cheap end of serious filtration. A polarizer or a stack of grad NDs at 77mm is common and affordable, and that is where the 24-105 earns its keep on a landscape outing. When you screw on an ND to drag a shutter past a moving stream, dial the filter factor into Zone Light Meter so the metered exposure already accounts for the light you are pulling out, rather than guessing the stops in your head while the cars pile up behind you. The constant f/4 helps here too, since your aperture does not drift as you zoom and your metered combo stays put across the range.

Today it sits in the used market as one of the best value buys in the EF lineup. People who do not need the f/2.8 stop or the bragging rights buy this, adapt it to an R body, and never think about it again. That is a kind of praise.