I don't know if this is the "rest of the story" but I was under the impression that if you ran out of image circle, you would get light fall off. The softness is in the negative. It is a Rodenstock Lens. The enlarging lens was a 105mm Nikkor. The scene is a field of flowers with the closest at 3 feet - The camera was 24" off the ground and I focused using a good loupe. The Image seemed sharp end to end at F5.6 and I stopped down to F32 because of the slight tilt. The image went from 3 feet at the foot to infinity and the mountains in the background in sharp focus. The flowers in the forground center are sharp, The flowers at the left and right and the mountains are sharp. The lower corners are soft where there is the greates distortion caused by the short lens. The exposure was 1/2 sec at F32 with Fuji Color sheet film at the rated ASA 160 and processed dip and dunk commercally at a local lab. I did the enlarging myself. I posted the image - poppy field