The Camera
Types of CamerasPrior to the digital revolution, all photographers would have used a film-based camera, which controlled the amount of light coming through the lens via a shutter mechanism and aperture, before finally reaching a strip of unexposed film. All cameras share the same principle as a camera obscura, effectively controlling the light entering a darkened space. Have a look at the slideshow for examples of different types of cameras, including digital cameras.
35mm SLR Film CameraAt school, we use SLR (Single-Lens Reflex) cameras which require 35mm film. The term SLR refers to the way in which the light passes into the camera lens and allows the viewer to see directly through the lens due to a mirrored 'shutter'. When the shutter release is pressed the mirrored shutter opens and light hits the film for a certain period of time. Therefore, the shutter serves two purposes: as a mechanism for allowing light to hit the film for a fixed time and as a viewer. See Fig. 1 for a cross section illustrating the principle.
Controlling Light IntensityTo control the intensity of light, the camera allows a certain amount of light to come through the lens and is controlled by the 'aperture' ring.
It is essentially the combination of light intensity and the time it is allowed to pass through the lens that makes an exposure (evenly lit photograph). You will learn more about this principle later in this tutorial. |
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Types of Film
Photographic film is made of a type of plastic/acetate that is coated in a light-sensitive emulsion.
The sensitivity of light is measured using a unit called ISO (which is a standard used across the world and is an acronym for 'International Standardization Organisation). Note: They used to be measured in ASA. The lower the number, the less sensitive (or more resistent) the film is to light. Conversely, a higher ISO means that the film is more sensitive to light and therefore needs less light to become exposed. Here is a basic breakdown of different sensitivities:
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Loading & Unloading Film
LoadingMost shop bought films come in the form of a metal canister with the start of the film poking out and ready to load. Sometimes, you get films that are in plastic canisters and these are usually rolled manually. If there is no film poking out, you will need to use a 'film puller'. Watch the video for instructions on how to load and unload film from a 35mm SLR camera.
UnloadingHaving taken your film, it is very important that you do not open your camera without having checked that the film has been rewound. Watch the video to see how film in a standard SLR manual camera is unloaded.
Be warned, however, that there are many different models of SLR film cameras and they all have slightly different ways of unloading film, but the principle is the same: you 'unlock' the film from the wind-on reel using through a button underneath the camera and then rewind the wind-on until you hear a click (indicating that the film has come off the wind-on reel) or watch the button until it stops rotating. See Fig.1 for an example. Your teacher will also demonstrate this in class. IMPORTANT TIP If you are even in doubt as to whether your film is rewound, then go into the blacked out 'film transfer cupboard' and open the camera. It only takes a second of light to ruin a whole unprocessed film so be cautious! |
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Taking Photos
No doubt, you will have used an automatic camera in the past and learned to take photos at the click of a button. In the following tutorials, you will learn how to use the manual SLR camera to 'expose' film, which is essentially the process of taking a photo by allowing light to pass into the camera and hit the film for a specific amount of time and intensity.
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Focal Length
Fig. 1 shows an SLR camera (Pentax K1000) with a 50mm lens attached. The perspective achieved by the lens is known as focal length, which is measured in millimeters (mm). A standard 50mm lens gives the same perspective as the human eye.
Any lens that has a shorter focal length i.e. 18-50mm lens, will result in a wide angle perspective. A very wide angle lens would achieve a fish-eye effect and look distorted. Conversely, any focal length over 50mm will magnify the scene and is known as a telephoto lens. Click on the example below to view the differences: Zoom Lenses
Some lenses allow you to view a range between focal lengths and these are known as 'zoom lenses'. See Fig.2 for an example of a zoom lens. Focus When taking a photo, you will need to focus on your subject and this is usually the furthest ring on your lens and measured in metres or feet (see markings). |
Exposure
'The quantity of light or other radiation reaching a photographic film'
Achieving an even exposure is a combination of having the correct shutter speed and aperture settings, which in turn will lead to a photograph where there is a good distribution of tones from dark to light. An under-exposed image is too dark and an over-exposed image is too light. Sometimes a scene has too much contrast and it will not be possible to get a good even exposure from a single shot. An artist may choose to under- or over-expose an image for dramatic effect, but as a beginner, you should aim to capture sharp, even exposures that show a good fundamental understanding before breaking the rules! |
Shutter Speed
Long Exposures
It is possible to have the shutter open for one second or more using B (Bulb), which means that you can keep it open for as long as you like manually. This is known as a long-exposure. However, there is a danger with this since the camera will shake as you hold it and any moving parts of your scene will come out blurred. Unless this is deliberate, it will often lead to disappointing results. Therefore, most photographers will not take photos under 1/60 second unless using a tripod and if the scene does not contain any moving objects/subjects. NOTE: A blurred image is not the same as an image out-of-focus! |
Aperture
The aperture determines how much light is exposed in the shot. See FIg. 2 for the different sizes of the aperture opening, which is measured in f-stops.
It is important note that the lower numbers equal more light exposure, which might confuse you at first. F/2.8 opens the aperture up to let a lot of light in, which is good in low light situations. F/16 only lets in a little light, and is good on bright days when there is a lot of natural light. |
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Depth of Field
The aperture setting (f-stop) that you use will have an impact on the amount of focal range in focus in front and behind your subject. This is known as the Depth of Field (DOF) - see presentation on right hand side for further details.
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Measuring Light
In order to determine the correct shutter speed and aperture, your camera needs to assess the amount of light entering the camera. It does this through a built-in light meter, which mesures the light and applies a formula to give an even exposure.
Most cameras have a meter built-in to their main camera body know as TTL (Through The Lens) metering. However, if you wish to make more precise measurements of light, you can purchase a hand held light meter like the one above. This is generally used by professions to assess the variation of light in a scene and pinpoint certain areas for exposure. Your built-in light meter has to make intelligent guesses about the exact area of exposure and can be unreliable. More advanced cameras have settings which allow you to program how your camera assesses the light. |
Film Sensitivity
Changing your ISO/ASAAlthough an even exposure is reliant on the correct speed and aperture setting, sometimes the scene is too dim and it means that you would need to take a photo for less than 1/60 second. This means that there is the possibility of camera shake from your hand and also the possibility of blur from the movement of your subject/scene as explained above.
You have one other possibility to improve your chances of taking a picture that is not blurred and that is by changing the ISO setting (or changing the type of film if using analogue). This must be done before changing your speed and aperture settings on a digital camera) As explained earlier, the ISO is a standardised number (i.e. 100, 400, 1600) that determines the sensitivity of the film/digital sensor (CCD). The higher the number, the more sensitive and more applicable to low light situations. The disadvantage with a high ISO is that the quality is grainy - see Fig.1. Fig.2 illustrates the 3 main variables when trying to capture the correct exposure. Like all art forms, there is a subjective element to what effects you want, but try to start by getting a sharp, well exposure image with no motion blur. |
Priority Modes
Most cameras have an 'automatic' mode where the camera chooses all the settings, but you can have more control over your camera by determining the shutter speed so that it will then give you the correct aperture setting and vice versa.
On a manual SLR camera (see Fig.1), you choose the speed settings using the dial next to the wind on mechanism and then look through the camera to check the light meter settings and determine the aperture. This is known as 'Speed-priority.' However, it is possible to also choose the aperture and then change the speed dial to suit the aperture you require. This is know as 'Aperture Priority' and is usually used when photographing landscapes to get a wide depth of field of portraits with a shallow depth of field. You can choose any combination of settings on a manual camera as it is manually operated. This is not the case, however, on digital cameras and they must give a range of choices known as 'modes' that need to be programmed. Fig. 2 shows the most common modes available: S-Mode - Speed Priority A-Mode - Aperture Priority M-Mode - Manual P-Mode - Program |