light theory (oya)

This report will discuss a basic understanding of the theory of light such as Colour temperature ( White Balance in videa) Lens Structure Types of lenses F Stop Depth of field The inverse square law COLOUR TEMPERATURE ( White Balance) Colour temperature setting in the camera tells it how it should see white. When properly adjusted the camera sees the colour white as white and then adjust for all other colour accordingly. Colour is light. The colour of an object is based on a combination of factors the Colour of lights the nature of the material they are hitting and how light it is being reflected off the object. LENS STRUCTURE Lens is an optical device used in conjunction with a camera body and though which light is focused this mechanism to make images of objects chemically or electronically. To focus light onto the photosensitive surface at the back of the camera. This can either be photographic film or CCD (charge- coupled device. ) Every lens has been examined to determine how they affect light and what degree. The focal length of a lens determines it is angle of view, and thus also how much the subject will be magnified for a given image position. The structure and operation of the eye is very similar to camera lens. Both are based on two major components: a lens assembly and a imaging sensor. The lens assembly captures a portion of the light emanating from an object, and focus it onto the imaging sensor. One key difference between a camera and the eye is that a camera does not focus light onto the photosensitive surface by adjusting the shape of lens. Instead the focusing screws move the lens forward or backwards in order to focus the image onto the photosensitive surface. DIFFERENT TYPES OF LENSES ZOOM LENSES Most common type of lenses known to the use filming industry. This is so because with zoom lenses you can go telephoto or wide-angle at the push of a button. You can zoom in or zoom out with zoom lens. The advantage of zoom lenses over prime lenses is that you don't have to change lenses to get to tighter or a wider composition. It save time from switching lenses. This choice of lens is ideal for documentary and news gathering. The disadvantage of zoom lenses is the loss in image quality. PRIME LENSES (Fixed focal length lenses) Can't zoom in or zoom out. Every time the film maker wants to get tighter on his or her composition he can either physically move the camera closer to his subject or change the camera lens for one with a longer focal length and narrower field of view the telephoto lens. The image quality is far superior. Professional narrative filmmakers always prefer prime lenses. The disadvantage of prime lenses inconvenience of switching lenses. TELEPHOTO LENSES e.g. 50 mm (in 16mm film ) In comparison to normal lenses telephoto can get really tight on the subject. Also the image is optically enlarged to show fine details from a subject that is far away. The image is optically enlarged to show fine details from a subject that is far away. Telephoto lenses compress space making people and objects that are far apart appear really near one another. The disadvantage of telephoto lenses. Shallow depth of field and shakiness and movement are more pronounced and noticeable need to use a tripod. Movemeat is more pronounced when hand-holding a camera with a telephoto lens. WIDE ANGLE LENS e.g. focal length = 10mm ( in 16mm film ) By comparison wide angle lens are the opposite of telephoto lenses. Have a broader field of view and they can show sweeping panoramas of mountains, ocean and forests. They make objects look further away than they are. Shakiness is negligible with wide angle this choice of lens is ideal for handheld work. Long depth of field make all subjects look sharp. The disadvantage of wide angle lens when the wide angle lens is too short it bends the image and make the subject appear fat. NORMAL LENS e.g. normal = 25mm ( in 16mm film ) By comparison normal lens are halfway between telephoto and wide angle lenses. Normal lenses mimics what the human eye sees, without neither getting to close to subject, nor distorting it, nor compressing the distance among the plains. F STOP (APERTURE) aperture getting bigger or smaller. Main F stop = f1| 1.4 | 1.8 | 2 | 2.8 | 4.5 | 5.6 | 8 | 11 | f16 | f22 | Without light there are no images on cameras. Light controls what we see in a camera and how we see it. Because natural light changes constantly we need to able to control its intensity as it passes though the lens and into the camera as we are filming. Controlling the light is important because shooting with too much light and you have an over exposed image and not enough light gives us an under exposed image. F-stop it is one mechanism by which we control the amount of light is hitting the film. DEPTH OF FIELD Depth of field is the distance between the nearest + farthest object in a shot that appear in focus. It's the area of your image that's in focus. In other words you can use it to make blurry background very little in focus except the main subject. ( narrow depth of field) and deep focus ( large depth of field) almost everything is in focus. THE INVERSE SQUARE LAW Is a principle that explain light states between distance , a light source, subject and time. Base on two principle A- light loses power if you increase distance from the the light to the subject. B- you will lose this light at a faster when distance get longer rate than you think. Below the chart is enlarged to help visualise this