How A Pinhole Camera Works

An excerpt from From pinhole to print – Inspiration, instructions and insights in less than an hour. How a photographic camera without a lens can be used to accept pictures and explanations of how a pinhole camera works.

Pinhole cameras rely on the fact that light travels in straight lines – a principle called the rectilinear theory of light. This makes the image appear upside down in the camera. — Pinhole cameras rely on the fact that light travels in straight lines – a principle called the rectilinear theory of light. This makes the paradigm appear upside downward in the camera.

Ane matter that inspires many pinhole photographers is the craft of building their own cameras. Finding new materials or a perfect box can be like uncovering a hidden treasure.

The pinhole camera is amazing in its simplicity. It is, in its nigh basic form, a calorie-free proof container with light-sensitive material at i end and a pinhole at the other.

Pinhole cameras are characterized by the fact that they do not have a lens. If a photographic camera has a lens, information technology is NOT a pinhole camera.

When the shutter is opened, light shines through to banner an image on photographic paper or movie placed at the dorsum of the camera.

Pinhole cameras rely on the fact that light travels in straight lines – a principle called the rectilinear theory of light. This makes the image appear upside down in the photographic camera.

If the dimensions of your photographic camera and the size of your pinhole are right y'all can have a photo that will compete on a technical level with a photo from your digital SLR camera.

A small pinhole generally produces sharper images than a larger one. Nevertheless, if the pinhole is too modest, light waves may be scattered slightly at the edges of the pinhole and crusade baloney or loss of focus.

Smaller holes too increase exposure times, since they will let less light into the camera.

A focal length about equal length to the diagonal size of the paper or film is a normal focal length. A shorter focal length is called a wide-angle, and a significantly longer is referred to as telephoto. — A focal length nigh equal length to the diagonal size of the paper or moving-picture show is a normal focal length. A shorter focal length is called a broad-angle, and a significantly longer is referred to equally telephoto.

How focal length works in a pinhole camera

The focal length of your pinhole camera is the distance between the pinhole at the front of the camera and the newspaper or film at the back of the camera.

Focal length facts

Brusk focal length

Wide angle
Brusque exposure times

Long focal length

Telephoto
Long exposure times

The three photographs show the different effects when varying the focal lengths. The image on the left was taken with a pinhole camera with a focal length of 15 mm, the one in the middle used 30 mm and the one on the right 60 mm, all taken on 120-film / 2 1/4 — The iii photographs show the different effects when varying the focal lengths. The image on the left was taken with a pinhole photographic camera with a focal length of 15 mm, the one in the middle used 30 mm and the one on the right lx mm, all taken on
120-motion picture / two 1/4″ film.

A camera with a 100 mm focal length will produce an image circle with a diameter of 350 mm. A small image circle causes light fall off and vignetting at the edges of an image. — A camera with a 100 mm focal length will produce an paradigm circumvolve with a diameter of 350 mm. A minor image circle causes light fall-off and vignetting at the edges of an image.

Vignettes

When the light enters the pinhole at the front of the camera, it is projected onto the newspaper or movie at the dorsum in a circle. The diameter of the image circle is roughly three and a half times the focal length. Y'all may finish up with a black vignette around the image if you take a shorter focal length. And this may exist exactly what you desire.

The vignette appears considering light is forced to travel further to the outer edges of the circle leaving information technology underexposed. If you don't want this effect, brand sure the camera doesn't require newspaper that is larger than approximately twice its focal length.

A camera with a focal length of 3 inches volition produce an image with a bore of approximately x.5 inches.
The intensity of the light in your camera decreases as you extend the length of the camera. The light will exist stronger nearest the hole and gradually weaken every bit it continues towards the back of the photographic camera. This means that yous will demand longer exposure times for telephoto cameras.

Learn more in the Pinhole book