The applications of zone plates to lithography are well known: to pattern, to measure, and to align between levels. Recent work has shown that zone plates with low numerical apertures and as few as two zones can produce focused spots that are nearly diffraction limited and that have minimal side lobes. With x-ray lithography such zone plates can be used to pattern vias down to at least 30 nm in diameter. In addition, the small size of these zone plates permits them to be arranged in densely packed arrays, attractive for direct write and metrology applications. In spite of the importance of their potential applications, the imaging properties of these zone plates are generally unrecognized, and sometimes quite surprising. This work models zone plates with seven or fewer zones, as a function of their phase shifts and transmissions. X-ray wavelengths are emphasized, but the simulation results are supported by experimental work on zone plate geometries scaled up in size to the visible region. (c) 2006 American Vacuum Society.