We present a novel method for computing depth of field and geometry from a single 2D image. This technique, unlike the existing ones measures the absolute depth of field and distances in the scene from single image only using the concept of triangulation. This algorithm requires minimum inputs such as camera height, camera pitch angle and camera field of view for computing the depth of field and 3D coordinates of any given point in the image. In addition, this method can be used to compute the actual size of an object in the scene (width and height) as well as the distance between different objects in the image. The proposed methodology has the potential to be implemented in high impact applications such as distance measurement from mobile phones, robot navigation and aerial surveillances. © 2012 IEEE.