Shutter / Aperture / ISO

• Taking a properly exposed photograph requires a cooperation between a camera’s shutter, aperture, and film (ISO)

• the shutter and aperture adjust the amount of light that reaches the film

• Essentially the shutter speed, aperture, and ISO number are variables in a photo equation

Film / ISO

• Standard film you’ve probably seen before is most likely 35mm negative film

• Film also comes in a positive form, it is called Slide Film• Film Speed (ISO 100, 200, and so on) describes a film’s

sensitivity to light. The higher the number the more sensitive (“faster”) the film, and the less light it needs for the picture to be neither too light nor too dark.

• A setting of 100 to 200 is good for learning to shoot outdoors in sunny conditions. In dimmer light, speeds of 400 or higher are required.

• Digital cameras don’t use film, they have a digital light chip, they also have a built in, usually adjustable ISO setting.

The Shutter

• The Shutter-speed controls the length of time that the shutter remains open.

• A Shorter time decreases the likelihood that a moving object will appear blurred

• A longer shutter speed will let in more light, but often blur your picture

Shutter Speed

• The shutter controls the amount of light that reaches the film by length of time it remains open.

• Doubling the amount of time the shutter is open is called a “Stop” – it gives twice as much light.

• Shutter Speed is measured in fractions.

• Your camera usually denotes the shutter speed by displaying the denominator only.

• 1/1 = 1 sec• ½ = one half of 1 second, it may

be labeled “2”• 1/250 = one 250th of a second, it

may be labeled “250”• Don’t confuse 2, meaning 2

seconds, with 2 meaning ½ second; 4 meaning 4 seconds, with 4, meaning ¼ second, and so on.

Leaf / Between-the-lens Shutter

• There are 2 main kinds of shutters available to cameras.

• A leaf or between-the-lens shutter is generally located inside the lens itself. All view cameras and most point-and-shoot cameras use leaf shutters.

• A flash can be used at any speed.

• Lenses will cost more.• Actual shutter time will vary

from lens to lens

Focal-Plane Shutter

• The other shutter is a focal-plane shutter.

• A focal-plane shutter is built into the camera body and is located directly in front of the film.

• The shutter consists of two overlapping curtains.

• Lenses are less expensive.• Shutter speeds can be higher• Can’t use a flash when both

curtains are moving. If the shutter speed is too fast, a sliver of flash appears.

Motion Blur

Aperture / Opening

• The aperture (size of lens opening) controls the brightness of the light that reaches the film.

• The aperture adjusts the size of the lens opening – the diaphragm. The smaller the aperture opening the greater the depth of field

• The Depth of Field is the part of the image near to far that will be sharp and in focus.

• The aperture is more or less like the pupil in your eye

• The size of an aperture is measured by it’s f-number or f-stop

• The lower the f-number the bigger the hole.

• Few lenses provide a range of apertures greater than eight stops

• A lens with a larger aperture is considered “faster” than a lens with a smaller aperture. Faster lenses work better in low light situations than do slower lenses.

• The size of the lens opening (aperture) controls the amount of light that passes through the lens.

• Each setting is one “Stop” from the next, meaning, each lets in twice as much light as the next smaller opening, half as much as the next larger opening.

Aperture and Depth of Field

• Depth of Field is the area from near to far in a scene that is acceptably sharp in a photograph.

• As the Aperture changes, the Depth of Field Changes.

• The smaller the Aperture the larger the Depth of Field

• Top photo – f/2 (large aperture, small DoF)

• Bottom photo – f/16 (smaller aperture, larger DoF)

Shutter Speed and Aperture Together

• Both Shutter Speed and Aperture affect the amount of light entering the camera.

• To get a correctly exposed picture (neither too light nor too dark) you need a combination of SS and A that let in the correct amount of light for a scene and film speed

• Equivalent Exposures, Once you have the correct combination of SS and A, you can change one setting as long as you change the other in the opposite direction.

• Remember - Shutter Speed affects the sharpness of moving objects, Aperture affects the depth of field, sharpness from near to far

Sunny 16• The Sunny 16 rule (aka the Sunny f/16 rule) is a method of estimating

correct daylight exposures without a light meter. Apart from the obvious advantage of independence from a light meter, the Sunny 16 rule can also aid in achieving correct exposure of difficult subjects.

• The rule serves as a mnemonic for the camera settings obtained on a sunny day using the exposure value (EV) system.

• The basic rule is, "On a sunny day set aperture to f/16 and shutter speed to the [reciprocal of the] ISO film speed [or ISO setting].”

• For example:– On a sunny day and with ISO 100 film / setting in the camera, one sets the

aperture to f/16 and the shutter speed to 1/100 or 1/125 second (on most cameras 1/125 second is the available setting nearest to 1/100 second).

– On a sunny day with ISO 200 film / setting and aperture at f/16, set shutter speed to 1/200 or 1/250.

– On a sunny day with ISO 400 film / setting and aperture at f/16, set shutter speed to 1/400 or 1/500.

Sunny 16

• What settings would you choose for a Sunny Day using 200 ISO Film?

• f/16 , ISO 200, 1/250• An Overcast day

using 200 ISO film?• f/8, ISO 200, 1/250

Types of Cameras

Single-Lens Reflex (SLR)

Rangefinder/Viewfinder

Twin-Lens Reflex

Point and Shoot

View Camera