A dual-field-of-view optical imaging system having a primary field-of-view and a secondary field-of-view and comprising: a detector assembly including an imaging sensor; primary field-of-view objective optics configured to receive first electromagnetic radiation from a scene and to output the first electromagnetic radiation corresponding to the primary field-of-view of the system; secondary field-of-view objective optics configured to receive second electromagnetic radiation from the scene and to output the second electromagnetic radiation corresponding to the secondary field-of-view of the system; imager optics; a field-of-view selection mechanism disposed between the secondary field-of-view objective optics and the imager optics and configured to receive both the first electromagnetic radiation and the second electromagnetic radiation and provide an output to the imager optics, wherein the field-of-view selection mechanism is configured to pass the first radiation to the imager optics and selectively also pass the second electromagnetic radiation to the imager optics, such that the output from the field-of-view selection mechanism includes either the first radiation alone or a combination of the first radiation and the second radiation, the imager optics being configured to receive and focus the output from the field-of-view selection mechanism onto the imaging sensor, and the imaging sensor being configured to produce primary field-of-view image frames from the first electromagnetic radiation, and further configured to produce combined image frames from the first electromagnetic radiation and the second electromagnetic radiation together, the combined image frames including imagery from both the primary and secondary fields-of-view; and image processing circuitry coupled to the imaging sensor and configured to receive and process the primary field-of-view image frames and the combined image frames from the imaging sensor, the imaging processing circuitry including a frame buffer configured to store the primary field-of-view image frames sequentially one-by-one, the imaging processing circuitry further including an image reconstruction module coupled to the frame buffer and configured, for each combined image frame, to: receive the combined image frame; receive a prior stored primary field-of-view image frame (P n-1) from the frame buffer; compare the combined image frame with the prior stored primary field-of-view image frame to determine a content delta between the combined image frame and the prior stored primary field-of-view image frame; and produce an approximate secondary field-of-view image frame based on the content delta. a detector assembly including an imaging sensor; primary field-of-view objective optics configured to receive first electromagnetic radiation from a scene and to output the first electromagnetic radiation corresponding to the primary field-of-view of the system; secondary field-of-view objective optics configured to receive second electromagnetic radiation from the scene and to output the second electromagnetic radiation corresponding to the secondary field-of-view of the system; imager optics; a field-of-view selection mechanism disposed between the secondary field-of-view objective optics and the imager optics and configured to receive both the first electromagnetic radiation and the second electromagnetic radiation and provide an output to the imager optics, wherein the field-of-view selection mechanism is configured to pass the first radiation to the imager optics and selectively also pass the second electromagnetic radiation to the imager optics, such that the output from the field-of-view selection mechanism includes either the first radiation alone or a combination of the first radiation and the second radiation, the imager optics being configured to receive and focus the output from the field-of-view selection mechanism onto the imaging sensor, and the imaging sensor being configured to produce primary field-of-view image frames from the first electromagnetic radiation, and further configured to produce combined image frames from the first electromagnetic radiation and the second electromagnetic radiation together, the combined image frames including imagery from both the primary and secondary fields-of-view; and image processing circuitry coupled to the imaging sensor and configured to receive and process the primary field-of-view image frames and the combined image frames from the imaging sensor, the imaging processing circuitry including a frame buffer configured to store the primary field-of-view image frames sequentially one-by-one, the imaging processing circuitry further including an image reconstruction module coupled to the frame buffer and configured, for each combined image frame, to: receive the combined image frame; receive a prior stored primary field-of-view image frame (P n-1) from the frame buffer; compare the combined image frame with the prior stored primary field-of-view image frame to determine a content delta between the combined image frame and the prior stored primary field-of-view image frame; and produce an approximate secondary field-of-view image frame based on the content delta. receive the combined image frame; receive a prior stored primary field-of-view image frame (P n-1) from the frame buffer; compare the combined image frame with the prior stored primary field-of-view image frame to determine a content delta between the combined image frame and the prior stored primary field-of-view image frame; and produce an approximate secondary field-of-view image frame based on the content delta.