A performance comparison is made using a number of commercially available Deformable Mirrors(DM) in fitting both ocular and atmospheric wavefronts. Least squares phase fitting simulations are performed for five mirrors using experimentally obtained mirror influence functions. The DMs used cover a range of DM technologies with varying size and cost. The phase fitting performance of these mirrors is found to be a function of influence function shape, actuator density and available mirror stroke.© (2007) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.