What is a Pinhole Camera?
" A pinhole camera is a small, light-tight can or box with a black interior and a tiny hole in the center of one end. See illustrations below. You can design it to accept roll or sheet film or a 126-size film cartridge. The two ends of the camera are parallel. The end opposite the pinhole is flat so that the film is held in a flat plane. The pinhole has a cover to prevent light from entering the camera when you aren't taking a picture."
How to Make and Use a Pinhole Camera:
Can Or Box Pinhole Camera:
"When you make a pinhole camera for use with film that isn't in a 126-size cartridge, use a small, light-tight can or box as the camera body. You can use any can that has a tight-fitting top. A 2-pound coffee can makes a good pinhole camera. You can use a clean paint can, a vegetable shortening can, a peanut can, or even a cylindrical oatmeal box. If the can you use has a plastic lid, you can paint the lid black. Be sure to paint it inside and out; then before using it, check to make sure no paint has chipped off. Chipped or peeling paint on the lid will allow light to enter the camera and ruin your pictures. Paint the inside of the camera body with dull black paint or line it with black paper to prevent light reflections."
Pinhole camera made from a can:
" The Pinhole With a noncartridge camera, make the pinhole in the end opposite the removable end. It's easier to attach the film to the removable end. You can make the pinhole in the box or the can itself, but it's much easier to make it in a separate piece of heavy black paper or thin metal. Then fasten this piece over a larger hole cut in the center of the permanent end of the can or box. Heavy-duty aluminum foil or the backing paper from Kodak roll film is good for this purpose.
" For a camera with the pinhole 3 to 6 inches from the film, you'll get the best results if the pinhole is about 1/75 inch in diameter. You can make a hole this size by pushing a No. 10 sewing needle through the paper or metal to a point halfway up the needle shank. You'll get a smoother hole if you rotate the needle as you push it through. If you're using aluminum foil or paper, sandwich it between two lightweight cards while you make the pinhole. This will help you make a smoother, rounder hole.
" You can also make a good pinhole in soft aluminum sheet metal. Place the aluminum on a hard surface (such as tempered hardboard). Make a small hole in the aluminum with an awl or an ice pick. Don't press too hard--the tip should just barely break through the surface. The hole will be ragged. Enlarge and smooth it by pushing a No. 10 needle into it from the indented side. You can smooth the rough edges with very fine sandpaper and then open the hole with the tip of the needle. You can use the same method to make the pinhole directly in the metal of the can by working the hole through from inside the bottom of the can.
" If you make the pinhole in a separate piece of black paper or metal, you should now make a hole 1/4 inch or more in diameter in the center of one end of the camera body. Then tape your pinhole in position over the center of the hole. You can check your pinhole to make sure it's perfectly round by looking through the back of the camera. To see if the image is clearly visible, aim the camera toward a printed page to determine if you can see the letters clearly.
The Shutter and Viewfinder:
" The shutter for the camera can be a flap of opaque dark paper hinged with a piece of tape. You can use a small piece of tape to hold the shutter closed while you aren't taking a picture. A viewfinder for a pinhole camera, while usually not necessary, can be made of cardboard or wire. The larger frame should be slightly smaller than the film size and located directly above the pinhole at the front of the camera. If the film isn't square, the viewfinder should have its longer dimension parallel to the longer dimension of the film. The small frame is a sighting peephole directly above the film and squarely behind the center of the large frame. When you aim your camera at subjects closer than 5 feet, tip the camera up slightly to allow for parallax--the difference between the view you see through the viewfinder and the image recorded on the film. This effect is caused by the separation between the viewfinder and the pinhole.
Loading a Can or Box Pinhole Camera:
"You can load the camera either with film or fast photographic paper. Paper is easier to handle since you can load it into the camera under a safelight. If you don't have a safelight, you can work by the light of a flashlight covered with several thicknesses of red cellophane paper placed 6 to 8 feet away. Most film, on the other hand, must be handled in total darkness. Your choice of film or paper may depend in part on the exposure times. Paper, because it is less sensitive to light than film, will probably require an exposure of about 2 minutes for sunlit subjects. Film may require only 1 or 2 seconds for subjects in sunlight. If you decide to use paper, try KODABROMIDE Paper F (glossy), No. 2, Single Weight. You can obtain this paper in the 4 x 5-inch size available in 100-sheet packages, or 5 x 7-inch size in 25-sheet packages from your photo dealer (corners may have to be trimmed to fit a cylindrical camera). If you use film, you can cut up a roll of KODAK TRI-X Pan Film or KODAK T-MAX 400 Profesional Film, 120 size, into 2 3/8-inch squares or 2 3/8 x 3 1/2-inch pieces. This must be done in total darkness, of course. At night a closet will probably be dark enough if lights in adjoining rooms are turned off. Sheet film, such as KODAK ROYAL Pan Film 4141 (ESTAR Thick Base), is easier to use because it's flat. A camera made from a 2-pound coffee can will take a 2 1/4 x 3 1/4-inch piece of film or photographic paper. You can use a 3 1/4 x 4 1/4-inch piece if about 1/2 inch is clipped from each corner of the film or paper. A camera made from a 1-gallon paint can will take a 4 x 5-inch piece of film or paper. When you have the size of paper or film you need, tape it firmly to the inside of the end of your camera opposite the pinhole.
" The emulsion should face the pinhole. The emulsion side of photographic paper is the shiny side. The emulsion on roll film is on the inside of the curl. Sheet film is identified by notches cut into one of the shorter sides. When you hold the film in a vertical position with the notches in the top edge toward the right side, the emulsion is facing you. Another way to determine the emulsion side of either paper or film is to touch both sides with a moistened finger. The emulsion side will feel slightly tacky. Test near the edge to avoid a fingerprint in the center of the picture. You will need to tape down the four corners if you use cut-up roll film or paper. Taping two diagonal corners will work for sheet film. Close the camera, making sure the shutter is closed.
For Best Exposure:
" Exposure To get clear, sharp pictures, you must keep your camera very still while the shutter is open. Use tape or a lump of modeling clay to hold your camera to a table, windowsill, chair, rock, or other firm support. Lift the black paper to uncover the pinhole and keep the pinhole uncovered for the recommended time. Cover the pinhole with the black paper between exposures. The following table gives exposure recommendations for a can or box pinhole camera. These recommendations are approximate. It's a good idea to make three different exposures for each scene, as explained above, to be sure you'll get a good picture.
Processing and Printing:
" You can process black-and-white film or paper yourself by using the KODAK HOBBY-PAC Black-and White Film Processing Kit or the KODAK HOBBY-PAC Black-and-White Paper Processing Kit. Print film negatives in the usual way. If you use KODABROMIDE Paper to make your picture, make the camera exposure long enough to allow the resulting paper negative to be a little darker than an ordinary photographic print. Dry the paper negative and make a contact print from it in the normal way, with the emulsion (picture) side of the paper negative toward the emulsion (shiny) side of the printing paper.
Cartridge Pinhole Camera:
" A cartridge pinhole camera is very easy to use because you can load and unload the camera in daylight, make at least 12 pictures without changing the cartridge, and have your photo dealer process the film. With a can or box pinhole camera, you must cut the film, load and unload the camera in a darkroom, reload the camera after each picture, and process the film yourself.
" Materials Here are the materials you will need to make a cartridge pinhole camera: 1 cartridge of film, 126-size, such as KODAK GOLD 200 Film for color prints 1 piece of thin black cardboard, 1 1/4 x 5 3/4 inches 1 piece of rigid black cardboard, 1 1/2 x 2 3/4 inches, with a 1/2-inch-square opening cut in the center 1 piece of heavy aluminum foil, 1-inch square 1 piece of black paper, 1-inch square 2 strong rubber bands 1 No. 10 sewing needle, black masking tape, a nickel or a dime.
Assembling the Camera:
" 1. Measure and mark the large piece of black cardboard into four sections, each 1 7/16 inches wide.
" 2. Using a knife, cut through only the top layer of cardboard along each of the lines. This will make it easier to fold the cardboard. " 3. Fold the cardboard into a box and tape the edges together with the black tape.
" 4. Using only the point of the sewing needle, make a very tiny pinhole in the center of the aluminum foil. When you make the hole, rest the foil on a hard, flat surface.
" 5. Center the pinhole in the foil over the square opening in the small piece of cardboard. Tape the foil to the cardboard on all four edges.
" 6. Put the small piece of black paper over the pinhole and tape it along the top edge. Use a small piece of tape at the bottom to hold it down between exposures. See alternate shutter section for a more light-tight shutter.
" 7. Tape the cardboard with the pinhole to the box. Use plenty of tape, and make sure all the edges are taped together so that no light can get into the camera box.
" 8. Put the camera box into the grooved recess in the square opening of the film cartridge. This should be a tight fit so that no light can get into the camera.
" 9. Use the two strong rubber bands to hold the camera in place. " 10. Insert the edge of a nickel or dime in the round opening on the top of the film cartridge.
" 11. To advance the film in the cartridge, turn the coin counterclockwise. The yellow paper (visible in the small window on the label side of the film cartridge) should move. The film has borders and numbers printed on it. Turn the coin slowly until the third and fourth numbers in each series on the yellow paper show in the window. The film will then be in the proper position for picture-taking.
" You can make a more light tight shutter using the diagram and instructions below.
" 1. Cut two 1 1/2-inch-square pieces of thin black cardboard. In one piece, cut a l/2-inch square hole in the center (A). The other piece should be cut to leave a 1/4-inch border on 3 sides (B). This is your spacer.
" 2. Cut a 1 x 11/2-inch piece of thin black cardboard (C). This is your shutter, which should easily slide into and out of the spacer (B).
" 3. Tape or glue parts A, B, and D together. (Part D is the 2 3/4 x 11/2-inch piece of cardboard cut previously to make the lens.)
Taking a Picture:
" Your camera must be very still while you are taking a picture. Try taping your camera to a table, windowsill, chair, rock, or other rigid surface. Or you can use a lump of modeling clay to mount the camera firmly on a steady support, such as a kitchen stool. Aim your camera by sighting over the top surface. A viewfinder is not essential. To prevent light from entering your camera and spoiling the pictures, use the small piece of tape on the black paper to hold it down over the pinhole after each exposure. If you're using the alternate shutter, make sure the shutter is kept in the spacer between exposures.
Pictures made with a cartridge pinhole camera:
" The following table gives exposure recommendations for a cartridge pinhole camera. These recommendations are approximate. It's a good idea to make three different exposures for each scene to be sure you'll get a good picture. So take a picture at the recommended exposure time, one picture at twice the recommended time, and another one at one-half the time. "
" The eye is one of our five sensory organs which include the ear, the nose, taste receptors, and sensory receptors in the skin, mucous membranes, and other tissues. The eye is the most well defined of these structures and, therefore, the easiest to understand. The structure of the eye is like that of a house with a single, outwardly curved (convex) clear 'bubble window', the cornea, at the front and a lengthy 'fiberoptic' cable, the optic nerve, extending from the back. It is essentially an empty structure except for a doughnut shaped tissue, the colored iris, which allows varying amounts of light to pass to the back inside surface of the eye. The size of the opening in the iris, the pupil is controlled by muscles in the iris when the amount of light is excessive, the muscles make the pupil smaller, and vice versa.
" Light rays pass through the clear cornea, which because of its curved surface bends (refracts) the light rays, which are then squeezed closer together to pass through the pupil. Then, they pass through the normally clear lens (about the size and shape of an M&M) which has two (2) curved surfaces, the front and the back. Therefore, these light rays are bent (refracted) two more times on their trip to the back of the eye. Most of the trip of the light rays to the back surface of the eye is through the vitreous, a clear jelly which fills the space between the back of the lens and the retina, the inside lining of the back surface of the eye which contains specialized cells which convert light energy into electrical impulses. These cells are either called rods, which are for black and white images, or cones, which are for color images (like camera film.) What is truly amazing about the eye is that part of these cells in the retina (photosensitive cells) is a six inch appendage of the cell, the axon, which joins with other axons to compose the optic nerve which travels to the brain stem, the very top of the spinal cord, located in the very center of the brain. There, each axon connects with (synapses with) a cell or cells, and the axon of the receiving cell(s) travels another six inches to the back of the brain, the occipital lobe, where it synapses with a brain cell(s) to produce what we call vision.
" Therefore, the major functions of these parts of the visual system are:
Cornea - Refracts light rays
Pupil - Controls the amount of light entering the eye
Lens - Refracts light rays
Vitreous - Light traverses this space
Retina - Converts light energy to electrical energy
Optic Nerve - Transmits electrical energy from the retina to the brain stem
Brain Stem - Intermediate 'relay station' for visual fibers
Occipital Cortex - Final destination. Converts electrical energy to visual images."
A Perfect Eye:
" A 'Perfect Eye' would therefore have:
(1) a clear and unobstructed path from the front of the eye to the back of the eye.
(2) the proper balance between the length of the eye and the curvatures of the three refracting surfaces.
(3) properly functioning cells in the retina and brain which allow the conversion of light energy to electrical energy, the transmission of this energy, and the interpretation of the energy into what we call vision.
" Unfortunately, most people do not have 'perfect eyes.' Eyes that are too long or have too much refracting power (from the cornea and the lens) are nearsighted eyes, as images are focused in front of the retina. The opposite results when eyes or too short or have too little refracting poser. These eyes are farsighted, as images are focused (or would be) behind the retina. When light rays that are vertically oriented are not refracted the same amount as the light rays that are horizontally oriented, this condition is called astigmatism. An example would be when that eye looks at a building that is built as a square, it would appear as a rectangle with different vertical and horizontal dimensions being visualized. This example refers to strictly vertical (90 degrees) and strictly horizontal (0 degrees); astigmatism can occur at any angle between 0-180 degrees.
" The eye is truly like a camera because it not only requires proper focusing (refraction) but it requires a clear media through which light rays must pass. Any loss of clarity of the structures through which these light rays must pass will interfere with their successful interpretation within the visual cortex of the brain. Examples of disorders which might cause this scattering or absorption of light rays are opacities or swelling of the cornea (scars, edema, abrasions, etc.), opacification of the lens (cataract), and cloudiness of the vitreous (hemorrhage or inflammation.) Also, the receiving tissue, the retina must be functioning properly, as opposed to aged related macular degeneration, in which there is deterioration of the most important part of the retina, the macula.
" The eye is possibly the most important of our sensory organs. It is debatably the most complex. Fortunately, research centers around the world are working hard to understand the nature of eye disorders and to obtain solutions for a better-seeing world."
" The human eye is the organ which gives us the sense of sight, allowing us to learn more about the surrounding world than any of the other five senses. We use our eyes in almost everything we do, whether reading, working, watching television, writing a letter, driving a car, and countless other activities. Sight is the most precious of the five senses, and many people fear blindness more than any other disability. The eye allows us to see and interpret the shapes, colors, and dimensions of objects in the world by processing the light they reflect or give off.
" The eye is able to see in dim light or bright light, but it cannot see objects when light is absent. The eye changes light rays into electrical signals then sends them to the brain, which interprets these electrical signals as visual images.
" The eyeball is set in a protective cone-shaped cavity in the skull called the orbit or socket and measures approximately one inch in diameter. The orbit is surrounded by layers of soft, fatty tissue which protect the eye and enable it to turn easily. Six muscles regulate the motion of the eye. Among the more important parts of the human eye are the iris, cornea, lens, retina, conjunctiva, the macula, and the optic nerve.
" In a cows eye the iris is a dark color making it difficult to see where the pupil stops and the iris begins. The sclera covers the whole eyeball except the iris and pupil.
" The optic nerve links the eye to the brain allowing us (and the cow!) to see. Around the outside of the eye there are muscles that help us move our eyes around. There is also fat which cushions the eye from bumps.
" Sheree has cut through the colored part of the eye (the iris and pupil) and has released lots of watery liquid (you can see it on the paper around the eyeball). It is called the aqueous humor (Latin for 'watery stuff'). It is there to protect the lens and help the eye keep its shape. The first cut Alisha made was through the sclera (the white bit) and it was a lot tougher than she thought it would be. It has the job of protecting the eye from scratches and other damage so it has to be pretty strong. She has cut through into the back section of the eye and she found lots of clear jelly. This is called the vitreous humor (Latin for 'clear, jelly-like stuff').
" The vitreous humor (jelly) keeps the eye in shape. It also protects the important bits (we'll get to them in a moment) from bumps and sudden movements. This group also cut into t