An imaging device has an optoelectronic detector, a beam splitter, a field lens, a mirror, a control circuit, a memory and a power source disposed within a housing. The housing is configured to be mounted in an optical path of a scope. The optoelectronic detector is mounted outside of the optical path of the scope. The beam splitter is mounted in line with the optical path of the scope. The field lens is mounted in line with a reflected optical path of the beam splitter. The mirror is mounted such that the reflected optical path of the beam splitter from the field lens is reflected to the optoelectronic detector. The control circuit is connected to the optoelectronic detector. The memory is connected to the control circuit. A user interface is mounted on the housing and connected to the control circuit. The power source is connected to the control circuit.