A pinhole camera, a variation of Camera obscura, is a simple camera without a lens and with a single small aperture, a pinhole – effectively a light-proof box with a small hole in one side. Light from a scene passes through this single point and projects an inverted image on the opposite side of the box. Exposures can typically range from five seconds up to as much as several hours. The effect was noted in the 5th century BC in China and has been refined over the centuries.
A pinhole camera is completely dark on all the other sides of the box including the side where the point is created. This part is usually painted black, but black boxes are also used for this purpose. There is also a thin screen which looks like a projector sheet, and is put in between the dark side adjacent to the pinhole.
Up to a certain point, the smaller the hole, the sharper the image, but the dimmer the projected image. Optimally, the size of the aperture should be 1/100 or less of the distance between it and the projected image.
Because a pinhole camera requires a lengthy exposure, its shutter may be manually operated, as with a flap made of light-proof material to cover and uncover the pinhole. Typical exposures range from five seconds to several hours. The images that I make are usually from 2 min to 7 minutes.
NOTE: In really bright light, when using film, your exposure times can be in the SINGLE Second to half-second range.
Click on the first image below for my presentation on how to make a pinhole camera. ↓