Pinhole Photography

 

Brief Technology Guide for the experienced Photographer

 

Principle

The Pinhole image is formed inside a black box (camera) by rays of lights going through a small hole in the front. As with a lens the image is upside down.

 

Focal Length

The focal length is simply the distance of the hole to the back of the box. Eg. If the Pinhole distance to the back (film plane) is 100mm the focal length is 100mm.

Changing the distance Pinhole/ Film (with bellows or tubes) to 150mm will change the focal length to 150mm.

 

F – Stop

The f-stop is calculated by dividing the focal length by the pinhole diameter.

Fl / pinhole Ø

Eg. Focal length is 100mm, Pinhole diameter is 0.45mm, f-stop is 222.

100 / 0.45 = 222

This is best rounded to the nearest standard f-stop 222 = 256.

 

Optimum Pinhole size

The sharpest image is achieved by the “Optimum Pinhole Size”.

A hole to large or to small will lead to unsharp images. Keep in mind that a pinhole image is naturally soft.

The formula to calculate the optimum Pinhole size in mm is: ( √ fl x 0.00055 ) x 1.9

Eg. (The square root of the focal length times 0.00055 times 1.9)

( √ 100 x 0.00055 ) x 1.19 = 0.45 Ø.