This article concentrates on dynamic SIMS analysis using a magnetic sector instrument at micron and sub-micron resolutions with the ion microscope and ion microprobe modes. The advantages and drawbacks of both alternatives for recording measurements in laterally heterogeneous specimens are highlighted expecially concerning transmission and acquisition times. The ionization efficiencies and matrix effects under oxygen, cesium and gallium bombardment are compared. The ion microscope is shown to provide fast acquisition times owing to the parallel detection of the entire analyzed area and the most adequate mode for lateral resolutions above 1 mu m, whereas the ion microprobe provides better sensitivity and is best suited for high resolution. Combining cesium and oxygen ion sources provides, in most cases, a better ionization efficiency than the gallium beam but all three sources induce matrix effects which are shown to be much less critical using cationized species.