Extreme retrofocus zoom lens for single-shot, single-lens HDR photography and video

Traditional high dynamic range (HDR) photography is performed by capturing multiple images of the same scene with different exposure times, which are then digitally combined to produce an image with great detail in both its light and dark areas. However, this method is not viable for moving subjects since the multiple exposures are not captured simultaneously. Recently an alternative method has been developed in which beamsplitters are utilized to simultaneously record the same image on three identical sensors at different illumination levels. This process enables single-shot HDR photography as well as continuous HDR video. This paper describes the design of a 2.5x zoom lens for use in this application. The design satisfies the challenging working distance and ray angle constraints imposed by the placement of two beamsplitters between the lens and the image plane. The particular importance of first-order layout when designing a retrofocus zoom lens is also discussed.