A delta image sensor comprising an arrangement of pixels and acquisition circuits corresponding to at least one pixel. Each acquisition circuit includes a sensor circuit comprising a photosensor to generate a sensor signal, VSIG, depending on a light signal illuminating the photosensor; at least one analogue to digital conversion, A/D, circuit configured to convert a current VSIG to a digital signal; at least one digital storage circuit configured to store a representation of at least one digital signal corresponding to a previous VSIG; a digital comparison circuit configured to compare the level of the stored representation with the current VSIG to detect whether a changed level is present; and a digital output circuit configured to generate an event output when the level has changed. The repeat rate of the analogue to digital conversion is chosen from one or more repeat rates corresponding to modulation of the light signal.