exposure basics: learn to correctly expose your photographs

Exposure Basics:Learn to Correctly Expose Your Photographs

Presented by Don Hazelwood

Sunday, March 1, 2009

What is Exposure?

Exposure is the amount of light collected by the sensor or film in your

camera during a single picture.

photograph by Jonathan Assink - Attribution-No Derivative Works 2.0 Generic


What is Exposure?

Understanding how to correctly manipulate your

camera to achieve the exposure you desire is the key to taking good photos

every time.


How do we control the exposure?

Exposure is nothing more then the aperture

and shutter speed working together within

the ‘confines’ of a predetermined ‘ISO’.


(Aperture + Shutter Speed)^ISO = Exposure



opening in the lens through which light is admitted

designated by f

the smaller the number the larger the opening & vice versa

dependent upon the lens



depth of field is the portion of a scene that appears sharp in the image.

a smaller opening, f/16 will produce a longer depth of field

a larger opening, f/1.4 will produce a very narrow depth of field



the amount of time the sensor or film is exposed to light

designated in seconds or fractions thereof

dependent upon the camera body



a faster shutter speed lets in less light and can “freeze” objects in motion

a slower shutter speed will allow more light to enter and can also capture a sense of motion

the bulb setting, noted as B, allows the shutter to stay open as long as the shutter button is depressed



also known as film speed

is the measure of the sensor or film's sensitivity to light.

lower sensitivity (lower ISO speed) requires a longer exposure and is thus called a slow film

higher sensitivity (higher ISO speed) can shoot the same scene with a shorter exposure and is called a fast film.



the higher rated the film/sensor the grainer/noisy the image will be & less detail will be captured

film uses larger silver halide crystals

digital sensors have to increase the signal gain



Now for photographical math2



Aperture is measured in f/stops as indicated in the series below:

1, 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32, 45

1 being the largest opening45 being the smallest

each step to the right - HALF as much light allowed in



Shutter Speed indicates how long the camera shutter remains open to let light onto the film or sensor.

These usually aren't noted on your camera as fractions to save space, however they represent fractions of a second.

B, 15, 8, 4, 2, 1, 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 1/500, 1/1000, 1/2000, 1/4000, 1/8000




ISO or Film Speed is noted as follows:

25, 50, 100, 200, 400, 800, 1600, 3200



Measurement Review

• Aperture (noted by f ): 1, 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32, 45

• Shutter Speed (measured in seconds or fractions thereof): B, 15, 8, 4, 2, 1, 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 1/500, 1/1000, 1/2000, 1/4000, 1/8000

• ISO: 25, 50, 100, 200, 400, 800, 1600, 3200



The Sunny 16 Rule

• This is a GREAT starting point to learn expoure

• Normal Sunny Day outside

• Set aperture to f/16 and shutter speed (reciprocal seconds) to ISO film speed

• For example, for ISO 100 film, choose shutter speed of 1/100 second (or 1/125 second)

• (f/16 + 1/100 second)^100 = Proper Exposure


Now go out and take properly exposed Photos!


exposure basics: learn to correctly expose your photographs

Self Improvement