The effect of varying object to detector separation at constant and varying magnification has been investigated at an accelerating potential of 30 kVp. Edge-contrast enhancement provided by phase effects was investigated for a drinking straw and found to provide up to 2.52 +/- 0.02 x the contrast for a PVC Heaviside step function. An optimum magnification of 1.5 x was found to apply for the microfocus X-ray tube setup used. Imaging at nominal megavoltage energies was investigated using a Rapiscan Systems Eagle M4500 series scanner. For a fixed source-detector separation, increased magnification improved edge contrast and spatial resolution. (C) 2010 Elsevier B.V. All rights reserved.