A portable data collection device is provided for reading fluorescent indicia, such as barcodes. The device includes a housing with a pivotable image capture module. The image capture module includes an adjustable aperture, a color detector array for imaging light received through the aperture, and a removable flash module to provide ultraviolet light. Optics in the image capture module focus the light received through the aperture onto the detector array, in which the detector array is movable with respect to the lens to provide proper focus of an image onto the detector array. The adjustable aperture has an iris wheel to control the amount of light received by the detector array. A programmed controller is provided in the housing which operates responsive to a user interface to image and decode indicia, or capture color digital images in memory. A display on the housing shows images received by the detector array in a non-fluorescent imaging mode to target indicia to be imaged and decoded, where the controller automatically adjusts the focus of the image by adjusting the focal distance between the detector array and the lens. In response to user actuation via the user interface, the controller energizes the flash module to emit light, including the excitation wavelength(s), which enable the indicia to fluoresce, and the detector array receives fluorescent light to capture an image frame of the indicia. The duration of the flash is in accordance with the amount of light measured by a light sensor in the image capture module. The indicia in the image frame is then decoded by the controller to provide data representative of the indicia.