Pinhole Camera

The Pinhole Camera

In this laboratory exercise we will make a simple camera. This project will illustrate both the properties of light and the basics of photographic processing. To complete the experiment you should have a good quality (not blurry, not too dark or too light) photograph. You may need to repeat some of the steps until you have a good picture.

Read and follow all instructions carefully especially those on page 3. If you do not follow the instructions you will have problems later on and will have to go back and correct your mistake. This will waste your valuable time.

Part 1: Making the Camera
Making the pinhole camera may not take very much time, but it is important to work with care so that the camera will function properly in later use.

Have the instructor or TA check to see that your box is suitable for use as a pinhole camera. Obtain a signature on the last page.
Start with a box or other suitable container which is relatively sturdy and easily sealed. Decide where you are going to put the pinhole, where you are going to put the film, and how you will load the film into the camera. The film will be about 4 inches x 5 inches in size. There is a piece of paper in your tool kit which shows the size of the film. The film must be located opposite from the pinhole. If your box is smaller than 4 x 5 inches, the film can be cut to a smaller size. If your box is larger than about 8 inches on a side, you may need to construct an inner cardboard wall to hold the film. If this is the case, consult the instructor or a TA.

Make an opening 1/2 inch x 1/2 inch to hold the pinhole. This should not be larger than 1/2 inch x 1/2 inch or you will not be able to do the next step. Measure with a ruler. If working with a metal container such as a coffee can punch a hole 1/8 inch in diameter or larger using a hammer and a nail.

Obtain a piece of yellow brass sheet. Be careful the edges are sharp.
Make a pinhole in the brass sheet with the needle. Hold the brass against the metal base in the tool kit. Push the needle through the brass and pull it out. The idea is to make a nice round hole that is exactly the size of the needle. Do not tear the brass. If you have problems with this step ask for help.

Using the black tape, attach the brass sheet with the pinhole to your camera. Be sure the brass sheet is well-sealed on all sides. Also make sure the pinhole is visible from inside the box. The pinhole must be visible from the film location.

Carefully seal as much of the box as possible using aluminum foil. First seal over the corners and obvious cracks and openings using duct tape. Of course leave a method to load the film. Put the foil everywhere possible on the outside and seal around the pinhole. It might be useful to imagine that you are gift wrapping a present. Do not put any foil on the inside. It is absolutely essential to have a well-sealed box without any light leaks. The most likely source of problems is light leaking into the box. See the instructor for guidance if you have any questions.

Fashion a shutter over the pinhole using a piece of aluminum foil. Cut a piece of foil 6 inches x 3 inches. Fold this in half so it is 3 x 3 inches. Attach this as a flap over your pinhole. Tape securely at the top of the flap above the pinhole. At the bottom of the flap put one small piece of tape which is just sufficient to hold the flap down. Put a piece of plastic packing tape over the foil below the pinhole. This will help to keep the foil from being ripped by the tape holding the shutter closed. Remember you will need to be able to open and close the shutter to take your picture.

If your camera is made of some kind of shiny metal (like a coffee can), line the inside with black construction paper. This keeps internal reflections from exposing the film.
Calculate the "f-stop" of your camera. This will be used in determining the exposure time. Measure the distance from the pinhole to the location of the film. It is easiest to do this in centimeters (cm). In a camera the "f-stop" is the ratio of the lens focal length to the lens diameter. For the pinhole camera this will be the distance from the pinhole to the film location. In this case the "lens" is the pinhole. The diameter of the pinhole is .06 cm. Record your calculations below.

f-stop = Distance = ______________ = _____________

Pinhole diameter 0.06 cm

Use the exposure table to determine the exposure time to for your f-stop. If your f-stop is not listed, use the closest value. If you are not sure how to use the table, proceed to the next step and ask the instructor or TA for assistance.

Make a piece of aluminum foil to serve as a final cover over your box. This sheet should cover the entire top of the box. It should also fold down about 1 inch over the four edges (but not interfere with the shutter). Obtain a rubber band to hold this aluminum cover sheet in place.

Your camera is now almost ready to go. Have the instructor or TA check the camera. Things that will be checked:

Brass sheet sealed on all edges.
Pinhole visible from inside the box
Box light tight.
Film location accessible.
Shutter to block pinhole functions properly.
Aluminum cover ready.

Checked by: __SIGN ON LAST PAGE

When done, proceed to the film loading room to load the film into your camera. The film loading room and the darkroom are located in the basement of Vanderwerf in room 6 or room 17. IF THE DARKROOM DOOR IS CLOSED DO NOT OPEN THE DOOR TO THE DARKROOM. KNOCK AND WAIT FOR IT TO BE OPENED FROM THE INSIDE.

Part 2: Taking a Picture

In the Darkroom, the TA will help you load a sheet of photographic paper (film) into your camera. The shiny side of the paper should face your pinhole. Make sure your pinhole is covered once the film is loaded.
Obtain a weight to use in keeping your camera steady. It is essential to make sure the camera is held firmly in place by a weight, otherwise your picture will be blurry. Go outside to take a picture. In selecting a subject, it must be something that does not move as the exposure time will be several seconds. Buildings usually make good subjects. Also, try to find something that is well illuminated rather than in shadows. If it is sunny, position the camera so the back is to the sun, so the sun illuminates the subject. Subjects with a range of tones from dark to light photograph best. Something that is very dark or very light may not show much detail when photographed.
Find a place to set up your camera. The only way to aim the camera is to simply point it at the subject. The pinhole tends to produce a wide-angle image. Pointing the camera slightly upwards, or positioning it on a wall or bench will help to avoid getting too much of the ground in your picture.
Secure your camera so that is does not wobble or move while you are making an exposure. You cannot hold the camera while taking a picture since your body will move too much. Use the weight to secure your camera.
Remove whatever is covering the pinhole and make an exposure for the recommended time. Note that the exposure time may be a little different for each camera. Time the required exposure. Timing with a watch is essential.
When done making the exposure, carefully cover the pinhole (without shaking the camera). Hold the shutter down to keep it from opening accidentally.
Return to the darkroom for processing.

Part 3: Processing the Negative.
In processing your picture we will see how black and white film is developed. We are working in black and white because it is easier to process. Color film requires strict control of temperature during developing and is generally more difficult to process. Black and white is also less expensive. The pinhole camera, however, could be used to take color pictures.

In the darkroom, open your camera and remove the photographic paper.
Developing the negative involves 4 principle steps:

The developer: develops the image.
The stop bath: stops the developing process.
The fixer: removes unexposed silver particles from the film.
Wash: removes chemicals and residues from the photograph.

Proceed to develop your negative:

Put the paper in the developing solution. Leave it in for 1 minute. Hold the paper with the tongs and move it in the solution.
Move to the stop bath for about 30 seconds.
Put in the Fixer solution for 1 minute.

After fixing, the light can be turned on in the darkroom. The processing is almost completed, only the final wash remains.
Wash it for 3 minutes.
Examine your negative. Do you recognize what you were trying to photograph? Is the exposure time about right? If the exposure was correct the negative will have a range of tones from black to white. Here are some of the things to look for:

Totally black negative: light leaking in, camera is not well sealed.
Very dark negative: over exposed, use shorter exposure time.
Very short exposure but still all black: light leaking in, cover with foil.
Very light negative: under exposed, use longer exposure time.
Blurry: Camera moved during exposure.

Hang the washed negative up to dry. Drying should only take a few minutes. The negative can also be dried by blotting it with a towel.

Part 4: Making a Print.
When you have a good negative, the next step is to make a print (a positive) from the negative. We will use the simplest method for doing this called contact printing. In contact printing, the print is made exactly the same size as the negative. As the negatives are fairly large, this is not a problem in our situation.

Make sure your negative is dry.
Return to the darkroom.
Show the negative to the TA or instructor and obtain a recommendation as to exposure time for the print.
We will use the controlled light source with a timer. Obtain another sheet of photographic paper and place the negative face down on the film side of the new sheet. Put the glass over the two sheets to hold flat.
Set the timer for the recommended time and make the exposure.
Process the exposed photographic paper the same way that you processed the negative, using the developer, stop bath, and fixer.
Hopefully you now have an interesting picture.