The Disposable Camera
This report aims to explain and understand the fundamental workings behind the popular and revolutionary disposable camera. The connection between the Lens and the Film will have most emphasis and explanation where appropriate. This will be achieved by a physical dismantling and any online information available.
Photography is undoubtedly one of the most important inventions in history. It has enabled people to capture and cherish moments in time and preserve them for years to come. During its developing life the disposable camera has become inexpensive to manufacture, and thus cheap to the consumer compared with other more ‘user adjustable’ opposites.
The basic technology, first conceived in 1814, is fairly simple. It requires 3 standard elements; an optical element (the lens), a chemical element (the film) and a mechanical element (the camera body). It is the manufacture and assembly of these parts that create a precise image of what we see before us.
The basic overview of the device
Disposable cameras are all manufactured in the same manor; not to allow removal and reloading of the film. Instead, these single-use cameras are built around the film, with the main process of rolling it from one side of the camera to the other without a protective casing.
When the user is ready to take a picture, they “point and shoot” at the desired subject and press the shutter release button. This button activates a spring-loaded piece of plastic that flicks open for a pre-defined length of time. The length of time is usually defined by the International Organisation for Standardisation (ISO); this is commonly regarded too as the “shutter” or “ISO” speed.
The, now open shutter makes an impression on the film. All cameras’ work with the process of light – thus the inside of a disposable camera must be very dark. The light that entered the camera is focused and captured on a portion of the photosensitive film, creating a photo image. This printed film is then advanced into the container on the right to stop any more light from continuing to expose the film. As this happens a new section of the film is moved into position.
Once the film has been exposed, the physical camera body is no longer needed. To get the photos of the film it needs to be taken to a professional developer; here, the film is removed and developed (usually in a professional darkroom or in a commercial photo developing machine). The developed photos are then collected by the photographer while the casing is discarded or recycled.
The FujiFilm 35mm Disposable Camera
Under exposed photos have always been a criticism of disposable cameras, where not enough light is gathered through the pre-defined shutter mechanism. To combat this, the FujiFilm 35mm has a built in flash.
To activate the flash, a little flap on the front of the camera has to be pulled up, See Fig.01. This flap connects a metal strip inside the camera to the circuit board causing a charge to flow. This moves electrical energy from the pre-installed battery to the transistor ready for the shutter release to be activated. As the user presses the shutter release button, the charged transistor releases its energy to the flash causing light. However, this only happens if the red LED is lit on the top of the camera (indicating the flash is fully charged and ready to use). The flash is usually in sync with the shutter to “Freeze” the image.
The process in which the chemical film is pulled the correct distance for use with a new image is controlled by a series of gears on the top right of the camera. As the user turns the top right gear, the white gear (Fig.06) is pulled by the holes in the film; this pulls another gear until it reaches a “stop” position. This is how the camera knows when a new section of film is ready for exposure, also releasing the shutter button for the user to take another photo.
Simply, the film that the light image is produced upon is useless on its own. It is actually the chemicals that are on the film that react to the input light to cause the end photo result. The chemicals on the film are Silver Halide salts which are bonded by gelatine. The variable crystal size determines the sensitivity, contrast and resolution on the film.
The shutter mechanism is possibly one of the most important processes the camera must undertake through the capture process. Within the FujiFilm 35mm is relies highly on the springs to operate the removal of the shutter from the lens. As the user presses the shutter the white arm is released pushing a flap connected to the shutter. This pushes the shutter away from the lens, while the spring relocates it into the correct position. See Fig.07. At the same time the two circuit strips are connected, Fig.08.
The optical element is an essential part to any camera as it angles the light entering the device into a standard that the camera can read. At its simplest, a lens is just a curved piece of glass or plastic, which can slow down and angle the light to redirect it into a “real image” – what is in front of the lens. This make/model of camera incorporates a fixed lens; this basically means that the lens is not customisable by the user. In terms of taking a photo; an object cannot be focused upon if it’s too close to the camera.
The process of taking a picture can be explained very easily. As light travels into a denser medium, at an angle, it changes speed; as glass and plastic are denser materials than air, the light slows down as it enters the camera. Due to the light hitting the medium at an angle, some of the light will slow down before the rest, causing a resultant change in angle. This is commonly referred to as “Refraction”. Put simply, imagine you are swimming through water; eventually you reach a patch of oil at an angle. The side of your body that hits the oil first will slow down while the opposite side will keep the same potential energy and momentum as before, thus causing a change in direction.
In a standard converging or “Convex” lens, the glass curves out (away from the camera body). This makes the light bend towards the centre of the lens on entry. Effectively, this reverses the image horizontally. (Fig.09)
A standard disposable camera gives a minimum distance from the “real image”. This is its focal range. Anything below the given distance will be processed blurry as the lens cannot refract the light enough to focus on the film. The amount the light is angled on entry is proportional to the structure and curvature of the attached lens. (Fig.10). Standard compact disposable cameras have an aperture (size of the shutter hole) in the range of f/11 to allow the image to be in focus from 4 feet to infinity.
The standard lens used in cameras today is most commonly manufactured from a single moulded plastic sheet and mechanically pressed into the camera.
With the government clamping down on waste due to over consumption and the lack of re-using acceptable products, many companies now recycle disposable cameras. There are two options currently available; the first is to re-load the film and replace the original battery to brand new ones. The second is to send of the plastic parts, which are all fully recyclable, off to be remade into something else.
The disposable camera has become cheap, user friendly, inexpensive to manufacture and a brilliant way to capture images in time. Through many years of development, they have become smaller and more manageable becoming the device we all could not live without today. Although, by making it increasingly smaller and compact, it’s now fairly complex and contains a large number of parts, increasing the overall sale price. As a result, manufacture and assembly of the components would be very time consuming. The time has come for a completely robotic production and possibly a compact disposable camera that has the ability to place your SD card into and remove once the camera has been used.
1. Overview of how the camera works http://electronics.howstuffworks.com/camera.htm
2. Camera electronics http://www.howstuffworks.com/framed.htm?parent=camera-flash.htm&url=http://www.exo.net/~pauld/activities/camera_electronics.html
3. History of the Camera http://en.wikipedia.org/wiki/History_of_the_camera
4. What is photographic film? http://en.wikipedia.org/wiki/Photographic_film
5. Manufacture of a disposable camera http://www.ehow.com/how-does_4925657_how-disposable-camera-manufactured.html