Sony FE 400mm f/2.8 GM OSS Overview
Key Features

E-Mount Lens/Full-Frame Format
Aperture Range: f/2.8 to f/22
Three Fluorite Elements, One ED Element
Nano AR and Fluorine Coatings
XD Linear Motor AF System
Optical SteadyShot Image Stabilization
Power Focus, Preset Focus, Focus Limiter
Weather-Sealed Magnesium-Alloy Design
Fixed, Rotating Tripod Collar
Rounded 11-Blade Diaphragm
Fast G Master Super-Telephoto Prime

Blending advanced lens technologies with a refined and relatively lightweight design, the Sony FE 400mm f/2.8 GM OSS is a fast super-telephoto prime purpose-built for sports and wildlife shooters working in trying conditions. Offering reach and speed, this G Master lens also achieves remarkable image quality while remaining easy to use handheld, thanks to the balanced design an Optical SteadyShot image stabilization.

Innovative Optical Design

As part of Sony's esteemed G Master series, this lens is designed to achieve a balance of impressive resolution and sharpness along with distinctive and pleasing bokeh.
Large f/2.8 maximum aperture enables working in difficult lighting conditions and also provides extremely shallow depth of field for isolating subjects from busy backgrounds.
Three fluorite elements and one extra-low dispersion element minimize axial and lateral chromatic aberrations, as well as color fringing, for high clarity and color accuracy.
Nano AR coating has been applied to interior lens surfaces to suppress reflections that cause flare and ghosting.
G Master optical design also contributes to low spherical aberrations, for high sharpness, as well as a pleasing bokeh quality that is further benefits by a rounded 11-blade diaphragm.
Fast Focusing and Reliable OSS

XD (Extreme Dynamic) Linear Motor System quietly and quickly focuses on fast-moving subjects while shooting at high speeds.
High-precision XD motor system is also complemented by updated AF algorithms for improved responsiveness and quieter operation, further benefitting sports and wildlife applications.
Power Focus functionality for smooth focus during video recording.
Full-time DMF supports manually adjusting focus simply by turning the focusing ring, regardless of the focusing mode, and Linear Response MF provides a natural and responsive focus feeling for more precise manual control.
Focus range limiter switch and preset focus functions increase focusing efficiency either within a certain constrained range or immediately to a specified focusing point.

Optical SteadyShot image stabilization compensates for the effects of camera shake to better enable making sharp shots when working handheld.
When used on a camera body featuring in-body image stabilization, 5-axis stabilization is available for more robust support.
Three difference stabilization modes can be used depending on the shooting situation: Mode 1 for general shooting, Mode 2 for panning shooting, and Mode 3 prioritizes accurate framing when photographing and tracking fast and erratically moving subjects.
Professional Durability and Intuitive Handling

Weather-sealed construction to protect against dust, dirt, and moisture.
Fluorine-coated front element resists dirt and fingerprints and is also easier to clean.
Weighing just 6.4 lb, this lens is incredibly portable for an f/2.8 super-telephoto. The weight of the lens is also distributed toward the back, where it would sit over a monopod, making tracking subjects and panning easier.
In addition to the weight-saving use of fluorite elements in the optical design, the external barrel design makes extensive use of magnesium alloy to contribute to the lightweight-yet-durable construction.
Increased mount strength for ensured rigidity that will withstand professional use.

Function ring near the front of the lens can be set to control a preset focus position or can be assigned to power focus or other selectable features via an in-camera menu.
Four separate focus hold buttons can be customized to adjust or activate a variety of settings, such as Eye AF.
The rear of the lens features a drop-in filter slot that accepts 40.5mm round filters.
Rotating tripod collar features ball bearings for smooth movements along with detents at each 90° position for intuitive handling. These clicks can also be deactivated.
As an additional weight-saving element, the included lens hood is made from carbon fiber.
Compatible with optional FE 1.4x and 2.0x teleconverters.

Sony FE 400mm F/2.8 GM OSS Specs
Focal Length 400mm
Maximum Aperture f/2.8
Minimum Aperture f/22
Lens Mount Sony E
Lens Format Coverage Full-Frame
Angle of View 6° 10'
Minimum Focus Distance 8.86' / 2.7 m
Maximum Magnification 0.16x
Optical Design 23 Elements in 17 Groups
Diaphragm Blades 11, Rounded
Focus Type Autofocus
Image Stabilization Yes
Tripod Collar Fixed and Rotating
Filter Size 40.5 mm (Drop-In)
Dimensions (ø x L) 6.22 x 14.13" / 158.1 x 359 mm
Weight 6.4 lb / 2895 g
Packaging Info

Package Weight 20.5 lb
Box Dimensions (LxWxH) 24.8 x 16.8 x 13.8"

In the box :
Sony FE 400mm f/2.8 GM OSS Lens
Front Lens Cap
Sony ALC-R1EM Rear Lens Cap
Sony ALC-SH155 Lens Hood
Lens Strap
Hard Case
Case Strap