With a camera object selected, enable the Focus Tool found in the toolbar to click anywhere in the viewport to set your camera’s focal plane.

3D artwork by Vadim Sorici.

Additionally, you can:

• Click and drag with the left mouse button (LMB) in the viewport for an interactive adjustment to the depth of the focal plane. 
• Hold down Ctrl while click-and-dragging with the Focus Tool to adjust the aperture value, similar to adjusting a real-life camera’s F-Stop. 
• Click the middle mouse button (MMB) in your viewport at any time to set the focal plane. 

This tool is controlled by the Depth of Field settings found in a camera’s Lens category of settings. Check out our Depth of Field quick guide to learn more.

Note: With physical-style camera controls, the scale of the objects in your scene becomes more important. If you notice that the range on the aperture dial seems to be off, check the Imported Units in the Scene object. This should be set to match the working units in your 3D modeling application. You can also enable Show Scale Reference in the Viewport Settings to get a proper sense of the scale of your scene.