Olympus M.Zuiko 75-300mm f/4.8-6.7 II MCS Ultra Zoom Telelens

The autofocus locks on quickly even in tricky light, which makes tracking birds in flight feel effortless. At this weight, it's a dream to carry for a full day hike without fatigue.

I'm really impressed with how much reach this gives you without weighing down your bag—I can shoot birds across a pond and still get sharp detail. The autofocus is quick enough for my amateur wildlife shots, though I wish it opened a bit wider in low light.

This lens is incredibly light for the telephoto range it covers—I can hike with it around my neck all day without any strain. I finally got clear, detailed shots of a heron across the pond that my kit lens could never reach. The image stabilization makes handheld shots at 300mm totally usable.