Shutter Speed Aperture ISO/ASA Exposure Shutter Speed Aperture ISO/ASA

CAMERA OBSCURA

EVOLUTION OF THE CAMERA… Camera Obscura Large Format Camera

Understanding exposure 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

Longer shutter speeds = more light Controls the speed at which the shutter opens and closes The shutter blocks all light from exposing the film UNTIL you press the button. Then it quickly opens and closes, giving the film a brief flash 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 as 1/500 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 tripod

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 focal length 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 DEPTH OF FIELD 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 photograph 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 film speed, 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)