Methods and apparatus for determining a depth of an object within a scene are provided. Image data of a scene can be captured using a lens configured to project an image of the scene onto an image sensor. The lens has a known focal length and is movable between at least a first lens position and a second lens position. A first image of the scene is captured with the lens at a first lens position, and a second image of the scene is captured with the lens at a second, different position. By measuring a first dimension of the object using the first image and a second dimension of the object using the second image, a depth of the object may be determined based upon a ratio of the first and second dimensions, the focal length of the lens, and a distance between the first and second lens positions.