Activate a Camera viewport. > Viewport controls > Field-of-View
Activate a Perspective viewport. > Viewport controls > Field-of-View (on Field-of-View flyout)
Field-of-View (FOV) adjusts the amount of the scene that is visible in a viewport and the amount of perspective flare. The effect of changing FOV is similar to changing the lens on a camera:
Although the effect of Field-of-View appears similar to a zoom, the perspective is actually changing, resulting in increased or decreased distortion in the viewport.
In a Perspective viewport, Field-of-View defines the width of your view as an angle with its apex at your viewpoint and the ends at the sides of the view.
In a Camera viewport, Field-of-View controls the width of the area a camera views, and represents the arc of the camera's horizon in degrees. For a selected camera, you can adjust its FOV and Lens parameters directly to fine-tune the FOV you set in the viewport. See “To use FOV with Camera parameters” in the following procedures.
To use FOV with Camera parameters:
Press H and select the viewport’s camera in the Select Objects dialog.
Open the Modify panel to view the camera’s Parameters rollout.
As you drag Field-of-View in the viewport, the FOV and Lens parameters update interactively.
Set the FOV and Lens parameters directly, or click a button in the Stock Lenses group.
Note: Only the FOV value is saved with the camera. The Lens value (focal length) is another way to express and select the FOV.
Note: See Common Camera Parameters.
Note: Using the Perspective button in a Camera viewport also changes the FOV in concert with dollying the camera.