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A pinhole calculator is used to help you find the correct exposure for your pinhole camera. They are very simple to use.

Pinhole calculators come in a variety of forms. Manufacturers of pinhole cameras sell various versions. There are on line versions as well as downloadable applications.  I happen to like PinholeCalc from Concept House.

PinholeCalc is a tiny app that runs on a Mac.

Nearly every pinhole calculator requires some input in order to produce proper exposure information.

The camera's Physical Characteristics are input on the left side. The two important factors on the left are the focal length and the pinhole diameter.

In order to determine the focal length, measure the distance from the front of the camera (pinhole) to the focal plane.

The pinhole diameter can be calculated using the method shown in my previous post using a scanner.

 In the example below, a focal length of 40 mm is input into the data window.

The pinhole diameter which is determined by measuring the pinhole is then input in this case as 0.30.

Hitting return after each input will update the other numbers. In the example, a 40 mm focal length when using a .30 mm pinhole yields an f/stop of f/133.33.

The calculator can also be used to determine the approximate field-of-view depending on the sensor or film size.

The last thing required is the ISO of the film or the sensor setting on the camera.

Once the ISO is input, the exposures listed on the bottom right, will adjust to the appropriate times in seconds. In this particular example, you would use a 1 second exposure for Bright Sun and Partly Cloudy, 3 seconds for Overcast, and so on. These settings are guides to help you get close. I find that the settings are close enough to produce reasonable results. Once you have determined the exposures, you can simply print the resulting PinholeCalc window so that you can carry it into the field. With a homemade pinhole camera, I usually tape or glue it to the camera for a quick reference.

It is also possible to use the calculated aperture setting (f/stop) with a handheld meter.

 

PinholeCalc is a handy little utility that can be used to find the f-stop, optimum focal length, optimum pinhole diameter, and common exposure times based on film speed of a pinhole camera. A field of view calculator is also included. This program should handle just about all mathematical aspects of building and using a pinhole camera. The art is up to you!

Cost/License

PinholeCalc is freeware. You may use it as much as you like. If you would like to make a donation to our development fund then we would certainly not turn it away.

System & OS Requirements

Power Macintosh running OS X v10.1 or greater.

 

 

Source: Concept House

You can also use the Aperture Priority setting on your DSLR to produce automatic exposures.

 

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Find out more about pinhole photography here.

 Please read all of my posts at PIXIQ.COM

 

 

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