# Elements of Exposure.

## Presentation on theme: "Elements of Exposure."— Presentation transcript:

Elements of Exposure

Exposure The amount of light that is allowed to hit the film or the imaging chip in a digital camera

Three Things Control Exposure
F-stop: Size of lens opening. Amount of light the camera allows in. Shutter speed. Length of time the light is allowed into the camera. Film Speed: Film sensitivity to light You can change any of these as long as you change the other

Exposure Measured in increments called stops
Each whole stop is calculated in terms of halving and doubling Increasing an exposure by one whole stop will double the original amount of light. Decreasing an exposure by one whole stop will cut the original amount of light in half. Each of the three variables of exposure, f-stops, shutter speeds, and film speed are all measured in stops.

Stop F-stops, shutter speeds, and film speeds are ALL calculated in stops. There is one stop difference between: f/8 and f/11 1/60 and 1/125 of a second ISOs 200 and 400

Shutter Speed Like f-stops, whole shutter speeds are spaced one stop apart. The longer the duration the more light that gets to the sensor That means that a shutter speed of 1/60 lets in twice as much light as 1/125, and half as much as 1/30

Shutter Speed 1/1000 sec. 1/2 sec. 4 sec.

Aperture and F-Stops Lens opened up to f/2 Lens stopped down to f/11

F-Stop A numerical representation of the diameter of a lens aperture.
The “f” stands for the focal length of the lens in a fraction. The smaller the f-number, the bigger the aperture and the less depth of field. The bigger the f-number, the smaller the aperture and the greater depth of field.

F-Stops The f in f-stop refers to the focal length of a lens.
The slash / indicates division This means that an f-stop refers to the focal ratio. So in the case of f/8 on a 50 mm lens, it means 500mm is divided by 8=6.25mm, which is the physical diameter of aperture opening of f/8 in a 50mm lens. This works the same for all f-stops on all lenses. Lens opened up to f/2 See more in sidebar of page 61 Lens stopped down to f/11

F-Stops The numbers are set up so there is a difference of one stop between each whole f-stop number in progression. Smaller numbers let in more light. Bigger numbers let in less. F/8 lets in twice as much light as f/11, and f/16 lets in half as much light as f/11 Lens opened up to f/2 Lens stopped down to f/11

F-Stops Each f-stop number indicates a standard amount of light so..
f/8 on a 24mm lens lets the same amount of light as f/8 on a 500 mm lens.

Depth of Field An important part of every image
Refers to how much of the scene is in focus, both in front of and behind the subject or at whatever point the lens is focused.

Depth of Field f/2 The smaller the aperture or opening, the larger the number of the f-stop and the greater the depth of field in the image The larger the aperture or opening, the smaller the number of the f-stop and the less depth of field in the image Camera focused on the middle chess piece, the only object in focus with the f-stop of f/2 f/22 Camera focused on the middle chess piece, the only object in focus with the f-stop of f/2

Setting the Aperture Long Short Depth-of-Field Low F-stop High F-stop
3.2 High F-stop 16

Exposure Mode Controls
Auto (point & shoot) Program Shutter priority Aperture priority Manual setting

White Balance WB corrects for different lighting conditions
Controls on LCD from rear panel button

Typical Viewfinder Flash mode Macro mode Zoom Level Image Quality
Pictures Remaining

Exposure Bracketing Allows taking 3 shots at different exposures
Bracket can be set in 1/3 stop increments Exposure range can be set to –2 to +2 stops - .7 stop Normal exposure +.7 stop

Digital Camera has TWO zooms
Digital Cameras have: Optical Zoom Digital Zoom Optical uses the camera’s LENS Digital zoom uses only a portion of the camera’s megapixels (extrapolated means GRAINY!) T W

Effects of Digital Zoom

Camera Status Panel