Film generally produces sharper images than paper, but photographic paper is also an excellent material for initial experimentation. If the film plane is flat, the image may be overexposed at the centre and underexposed at the corners. Many pinhole photographers exploit this as a particular aesthetic effect, with blurry edges. A curved plane, however, keeps the film roughly at the same distance from the pinhole, and the light is more evenly distributed. Because the pinhole is small, very little light enters the box.
Exposures can range from half a second to several minutes, sometimes hours.
The aperture or f-stop can be calculated by dividing the focal length by the pinhole diameter. Pinhole photographs are softer and less sharp than pictures made with an ordinary camera. Objects that are 5 cm from the camera will be equally as sharp as objects several metres away. This cannot be achieved with an ordinary camera with a standard lens. In other words, some pictures made with a pinhole camera could not have been made with a lens.