Sony's flagship 600mm f/4 super-telephoto — fluorite-light, built for the pro sidelines.
The 2019 Sony FE 600mm f/4 GM OSS is Sony's flagship super-telephoto for the E-mount system, built for professional wildlife and sports work on the Alpha bodies.
At 3,040g it undercuts its DSLR-era rivals decisively: fluorite elements and a magnesium barrel put the balance point close to the camera, an 11-blade aperture and dual XD linear motors drive the G Master optical formula, and optical stabilisation works with the body IBIS.
Its significance is as the lens that completed Sony's professional sports system - together with the 400mm f/2.8 GM it removed the last reason agencies kept DSLR outfits, and it remains the long prime on Alpha 1 and A9-series touchlines.
Used buying: these are professional tools, so check the barrel for tripod-collar and monopod wear, verify the focus-hold buttons and OSS switchgear, and confirm the drop-in filter holder and original case are present - both move the price meaningfully at this level.