1. A method for calculating a distance from a camera to an object, comprising acts of: obtaining a first image of an object employing a first set of parameters; obtaining a second image of the object employing a second set of parameters; determining a width of blur at corresponding edges for each of the first and second images; generating a first estimate of the distance from the camera to the object such that the first estimate is obtained from at least the first image and the second image using depth-from-defocus based at least on an equality comparison of the width of blur determined for each of the first image and the second image; obtaining a third image of the object employing a third set of parameters, wherein the third set of parameters are based, at least in part, on the first estimate; obtaining a fourth image of the object employing a fourth set of parameters, wherein the fourth set of parameters are based, at least in part, on the first estimate; and determining a width of blur at corresponding edges for each of the third and fourth images; generating a second estimate of the distance from the camera to the object such that the second estimate is obtained from at least the third image and the fourth image using depth-from-defocus based at least on an equality comparison of the width of blur determined for each of the third image and the fourth image, the calculated distance from the camera to the object being based at least in part on the second estimate.