Prior to the development of lenses utilizing the Angénieux retrofocus concept, mirror lock-up was essential to wide-angle SLR photography.
This problem is resolved by constructing the lens as an inverted telephoto, or retrofocus with the front element having a very short focal length, often with a highly exaggerated convex front surface and behind it a strongly negative lens grouping that extends the cone of focused rays so that they can be brought to focus at a reasonable distance.