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Light & Exposure

Light & Exposure. Photography is the act of capturing patterns made by light or “drawing with light .” light rays entering the camera create a latent image on film by chemically changing the silver particles in the film’s emulsion. Light & Photography.

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Light & Exposure

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  1. Light & Exposure

  2. Photographyis the act of capturing patterns made by light or “drawing with light.” • light rays entering the camera create a latent image on film by chemically changing the silver particles in the film’s emulsion. Light & Photography

  3. Light is a form of electromagnetic radiation, or radiant energy, visible to the human eye. • When light is emitted from a source, it moves away or radiates in straight lines in all directions (This is why a room appears to instantly fill with light when you turn on a light switch.) Basic Light Theory

  4. Light waves have two characteristics that can be measured • Wavelength: the distance from one crest of one wave to the crest of the next (measured in Nanometer) • Frequencyis a measure is a measure of the number of waves (cycles) passing a given point in one second (Hertz) Basic Light Theory

  5. The portion of light that the human eye can detect or “see” is referred to as the visible spectrum. • Our eyes see the different wavelengths as different colors. • Structures in the eye called cones are receptive to three ranges of wavelength: • 400nm – 500nm (blue), 500nm – 600nm (green) and 600nm – 700nm (red) • Combined effect of the cones provides us with a full rainbow of colors. Basic Light Theory

  6. When light is composed of red, green, and blue wavelengths in approximately equal proportions, it is said to be “white light.” • The effect that the color of light has on black and white film is very slight. • Black and white film is panchromatic, meaning that it is sensitive to light in the blue, green, and red wavelengths. • This difference often results in colors that appear different to our eyes than being reproduced on black and white film as gray tones. (this is why we can use filters for red & green) Basic Light Theory

  7. When light strikes an object, one of three things will happen. Light will be: • Absorbed, or • Transmitted, or • Reflected • This depends on the material from which the object is made, the type of surface finish, and the object’s color. • Our perception of an object’s color is based on the wavelengths of light that are reflected from that object. • White or light-colored objects reflect light rays readily. • Black or dark-colored objects absorb most light rays. Basic Light Theory

  8. Exposure is the amount of light that enters the camera and hits the sensor. (The more light that hits the sensor the brighter the scene will be.) • Over-exposed: too much light hits the sensor (Image is bright, areas are “blown out” with light, details are lost) • Under-Exposed: not enough light hits the sensor (image is dark and details are lost in shadow) Exposure

  9. There are three camera settings that control the exposure, these are: • ISO speed: Controls the sensitivity of the sensor to light • ApertureThe aperture controls the size of the diaphragm over the shutter, the smaller the aperture number the more open the diaphragm is, allowing more light to enter. • Shutterspeed: The slower the shutter, the more light will enter the camera. Controlling Exposure

  10. Will control the sensitivity of the sensor • The lower the number, the less sensitive • For low light you will need a higher ISO number to make the sensor more sensitive. • (but higher ISO, the more noise (grainy look) will show up.) ISO SPEED

  11. Pro:Higher ISO allows shooting in lower light condition • Con:Higher ISO settings result in more digital noise ISO SPEED

  12. The larger the number the smaller the size of the diaphragm in the lens. • The more light that comes in at a particular shutter speed, the shallower the depth of field. • For more depth of field you use a smaller (higher number) aperture setting. • Pro:Larger apertures allow more light in and thus allow shooting in lower light conditions • Con: Larger apertures reduce the depth of field which may not be desirable APERTURE

  13. APERTURE

  14. APERTURE

  15. The faster the shutter, the less light enters the camera • The slower the shutter the more light will enter the camera. • Shooting in low light conditions, you may need a slower shutter speed. • However, too slow of a shutter may create blur from the subject moving or accidental camera movement. • Sometimes a little blur can help portray movement and action, a sharp bike rider with a blurred background will make the rider look like he/she is moving fast. • While blurring on other images can ruin the image. SHUTTER SPEED

  16. SHUTTER SPEED Pro:Fast shutter speeds can freeze action, slow shutter speeds can add a dramatic motion blur. Con: Fast shutter speeds require lots of light, slow shutter speeds are harder to control.

  17. Metering allows the user direct control over all exposure settings. • Set the shutter speed dial to the desired shutter speed. • Depress the shutter release button halfway as you look through the viewfinder. • The shutter speed, approximate aperture and bar graph will be displayed in the viewfinder • Turn the shutter speed dial or the lens aperture ring until a single dot is displayed in the center of the bar graph Metering

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