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Home , Shutter speed

EXPOSURE SPEED ISO/ASA OBSCURA EVOLUTION OF THE CAMERA…

Camera Obscura Camera

UNDERSTANDING

EXPOSRURE is one of the most critical elements of photography. There are three adjustable elements that control the exposure: ISO, Aperture and Shutter Speed. (4) ISO The measure of a camera sensor’s sensitivity to light

(5) Shutter Speed The amount of time that the shutter is open

(11) Aperture The size of the opening in the lens when a picture is taken

SHUTTER SPEED

• Controls the speed at which the shutter opens and closes • The shutter blocks all light from exposing the UNTIL you press the button. Then it quickly opens and closes, giving the film a brief of light. • You can control the length of time the shutter remains open by setting the SHUTTER SPEED. • It determines how long the shutter stays open. • The longer exposures ( like 1 second ) give much more light to the film than a 1/1000 of a second exposure. So even though the number may look bigger, don't be deceived! (Think fractions….1/2 of a pie is larger than 1/8 of a pie). Longer shutter speeds = more light Shorter shutter speeds = less light WHAT SHUTTER SPEED TO USE

• A standard shutter speed is 1/125 or 1/250 of a second – these speeds are appropriate for a normally lit outdoor shoot. • Bright, sunny day/ excessive light – use a faster speed such as1/500 • Overcast or late afternoon – a slower speed should be used, such as 1/60 • A shutter speed slower than 1/60 of a second should only be used with a LIST OF SHUTTER SPEEDS LIST OF SHUTTER SPEEDS

APERTURE

• Before light reaches film, it must pass through an opening called an "Aperture". • Like the pupil in a human eye, the aperture on a camera controls light. It does so by closing up to restrict light, and opening to let light in.

Smaller F-stop number = larger aperture opening Larger aperture openings = more light exposing film APERTURE

• The f stop number indicates a fraction of the aperture opening in relation to the of the lens • Each f stop allows half as much light as the f stop before it

The larger the f stop number, the smaller the hole in the lens (example f/5.6 is LARGER than f/22) WHAT APERTURE TO USE

• A standard aperture is around f.8 or f.11

DEPTH OF FIELD • The easiest way to understand how to control the zone of focus in a is to remember the following: • Large f stop number (for example, f.22) = large DOF • Small f stop number (for example, f.4) = small DOF

LIST OF F.STOPS ISO (INTERNATIONAL ORGANISATION FOR STANDARDISATION )

• Is the sensitivity of the film or imaging sensor to light • The ISO is often referred to as ‘light speed’ • The faster the , the higher the sensitivity of the film to light • The higher the number, the higher the degree to sensitivity

High ISO = Poor lighting conditions (for example indoors without a flash)

A METAPHOR FOR EXPOSURE

Imagine your camera is like a window with shutters that open and close. Aperture is the size of the window. If it’s bigger more light gets through and the room is brighter. Shutter Speed is the amount of time that the shutters of the window are open. The longer you leave them open the more that comes in. Now imagine that you’re inside the room and are wearing sunglasses. Your eyes become desensitized to the light that comes in (it’s like a low ISO). There are a number of ways of increasing the amount of light in the room (or at least how much it seems that there is. You could increase the time that the shutters are open (decrease shutter speed), you could increase the size of the window (increase aperture) or you could take off your sunglasses (make the ISO larger).