• A high-thrust HLA (High-response Linear Actuator) quickly moves the lightweight focusing group for quick focus switching and nimble tracking of fast-moving subjects.
• A new function ring can be configured to control one of two settings, depending on how its settings switch is set: in Focus Preset Mode, turning the ring will instantly shift focus to a pre-registered position. In Power Focus Mode, turning the ring allows for constant speed focus pulling (useful during video shooting) and the focus speed can be changed in two steps.
• Four separate AFL buttons make it easy to control focus position while tracking subjects.
• Focus Mode and Focus Limiter switches give further control on focus speed and range for even more control depending on what the subject is and how far away it is.

Helping to achieve sharp and stable images, this 300-600mm features a robust image stabilization system that compensates for 5.5 stops of camera shake at the 600mm position. Powered by Sigma's OS2 algorithm and using a dedicated drive unit, actuator, and high-precision sensor, this stabilization system is perfectly matched to the larger size and wider aperture design of this lens.

Additionally, for more refined control, two OS modes are available:

• Mode 1 is a general application stabilization mode, suitable for most photo and video situations.
• Mode 2 is a specialized setting for panning work and makes use of the OS2 algorithm to better stabilize shots while moving the lens horizontally, vertically, or diagonally, regardless of the camera's orientation.

Built for harsh environments, the lens features a highly durable design intended for use in trying conditions:

• Magnesium alloy barrel for durability without excessive weight.
• Dust- and splash-resistant seals for reliability in inclement weather conditions.
• The front element features a water- and oil-repellant coating that is especially easy to clean.
• Thermal insulation paint prevents overheating in extreme temperatures.