An imaging reader has an illuminating light assembly for illuminating a target with illumination light, and a solid-state image sensor with a rolling shutter for sequentially exposing an array of pixels to capture an image from the illuminated target. Target illumination is controlled by controlling an exposure time and a gain of the sensor, and by controlling an output power of the illumination light. The output power is maintained at a maximum level when the exposure time and/or the gain exceed a minimum threshold, and is lowered when the exposure time and/or the gain does not exceed the minimum threshold, while concomitantly maintaining the exposure time and/or the gain constant at the minimum threshold.