Here is an example of a pinhole image (cyanotype). "Focal length" was 7cm (pinhole to the center of the film) and it was 14cm from the pinhole to the corner of the film. Exposed onto an 8x10 piece of litho film. My nose is about 6 inches from the camera. Exposure was about 5 minutes (that is why my chin is resting on my hands.)
Image fall-off not noticable because the my face was the darkest part of the scene. The corners received relatively 2 stops less light than the center -- but the cyanotype is a straight print. Pick your scene carefully and use the fall-off to your advantage!