an image acquisition component configured to detect light having at least one wavelength, wherein the light provides discrimination between a background field and a quantity of imageable units located at a distance from the image acquisition component, and to provide, as an output, data representing the background field and the units;

an image processor configured to receive data from the image acquisition component, and further configured to interpret the data as a field image whereon are superimposed a quantity of countable units;

an operator interface component configured to present a count result output from the counter and to accept at least one command input to the counter; and

a counter controller configured to manage at least the image acquisition, image processor, and operator interface functions of the counter;

a first light source, wherein the first light source illuminates at least an area associated with the background field, wherein the first light source has a first spectral component, wherein light, emitted from the first light source and directed to units positioned to be detected by the image acquisition component, is thereafter directed at least in part to the image acquisition component;

a tray having a generally planar tray floor, substantially nonobstructive to light of at least one wavelength emitted by the first light source, and having a perimeter sidewall, wherein the sidewall substantially adjoins the tray floor and establishes a physical boundary for the tray floor that is open at least in part, wherein the sidewall rises above the tray floor to a specifiable extent;

a bracket whereby the tray is removably attachable to the counter;

a first hinge mechanism that links the tray to the bracket, wherein the tray is configured to rotate over a range that includes a first tray floor orientation that is substantially horizontal when the counter is in its normal operating orientation, and that further includes a second tray floor orientation that is tilted sufficiently to direct units resting on the tray floor toward the sidewall open part;

a pivotable stop bar affixed to the bracket by a second hinge mechanism, wherein tray tilt coupled to the stop bar opens a gap between the stop bar and the tray sidewall open part; and

a collection chute positioned beneath the sidewall open part, whereby units directed toward the sidewall open part and spilled therefrom are gathered into a lower opening of the collection chute.