Sony FE 600mm F4 GM OSS

Reviewers rate it as one of the best 600mm lenses made, with excellent sharpness and contrast from f/4 to the edges and practically no colour fringing. It keeps very high quality with the 1.4x converter and remains usable with the 2x. Bokeh is smooth and highlights stay round thanks to the XA element and individual calibration of each lens.

Autofocus is described as fast, decisive and quiet, and it makes full use of Sony's high-speed bodies. The usual criticisms are weight, size and price, plus a 4.5m close focus. The later 600mm f/6.3 GM and the 200-600mm zooms deliver much of the reach for a fraction of the cost.

Owners are mainly professional and serious amateur wildlife and bird photographers. They report very high keeper rates, excellent results with the 1.4x converter and dependable performance in rain and cold. The balance point near the mount gets frequent praise.

The complaints are about weight on long hikes, the need for a gimbal head or a heavy monopod, the size of the hard case and the hood, and the cost, which has risen since launch.