This chapter presents a comparison of eleven focus measures which are categorized in four main classes or groups. The performance of focus measures is evaluated by considering various factors that might hinder their smooth operation. These factors include illumination variation, texture reflectance, object distance variation, distance variation in between consecutive frames, and various types of noise including Gaussian, Shot, and Speckle noise. The focus measures are tested for depth estimation for 3D shape recovery using Shape From Focus (SFF) techniques. Three measures are used to compare the performance of the focus measures, namely, visual inspection as a qualitative measure and root mean square error and correlation as quantitative measures. © 2012, IGI Global.