A monopod can help with telephoto lenses, but not nearly as much as a tripod. In practice, photographers often report roughly 3–4 stops of improvement over the old hand-holding rule of thumb (about 1 / focal length, adjusted for crop factor) with a non-stabilized lens, though results vary with technique and lens weight. With lens or in-body stabilization, a monopod may add another stop or two.

Its biggest real-world advantage with telephotos is often not absolute stabilization, but supporting the weight of a heavy lens so your muscles don’t tire and introduce more shake. That’s why monopods are common in sports and wildlife shooting: they improve comfort and keeper rate during long sessions while still allowing fast repositioning.

A monopod is less useful for very long exposures, where a tripod is the better tool. For moving subjects like sports or birds, though, you usually need a fast shutter anyway, so the monopod’s value is mainly steadiness, reduced fatigue, and easier handling of large lenses rather than replacing a tripod.