Perspective difference DP Merrill vs. DPx
It is the angle of view that determines how perspective is rendered. The angle of view is determined by the size of the sensor and the lens's focal length. A 75-85mm lens on a 4*5 has more or less the same angel of view as a 21mm on a 35 mm, given the different ratios of the formats 1.5 (35mm) vs 1.25 (4x5.) I often make panoramas with 90° to 120° angles of view. By the way, stretching distortion as one approaches the corners is the nature of perspective projection. Our eyes don't do that because they are in constant motion, building scenes with tiny images using the 10° angle of vision of the fovea - the center of high definition vision in the human eye.