Relational Exposure Techniques

While it may seem confusing at first, the aperture and shutter speed controls on your camera operate in a synchronized and organized way when their relationship is understood. These controls allow you to preconceive the image you would like to create and then execute it, whether you’re shooting a digital, or a film camera. Each major F-stop and Shutter Speed allows exactly either one half or twice the amount light to enter your lens as the one next to it.


Shutter Speeds
Consider these shutter speeds which determine how long the shutter of the camera is open.

500 ~ 250 ~ 125 ~ 60 ~ 30 ~ 15 ~ 8 ~ 4

Keep in mind that 500 is actually 1/500 of a sec, so 1/250 is double the exposure time and same with the rest of these speeds. Moving from left to right, each of these shutter speeds is exactly double the exposure time of the previous one.


F-Stops
The F-stops control the diameter or size of the lens opening.

F2.8 ~ f4 ~ f5.6 ~ f8 ~ f11 ~ f16 ~ f22 ~ f32

Some confusion may arise since the f-stops while not numerically symmetrical; they also allow exactly either one half or twice the light to enter through your lens as the one next to it. Moving for left to right on the above scale each F-stop allows one half the amount of light to enter the camera as the previous one.

Since each of these controls represents either one half or double of the one next to it, they can be used in different combinations to produce the same amount of light or exposure entering the camera. Consider these exposure combinations stated as a thirtieth at f2.8 (first one).

30 @ f2.8 ~ 15 @ f4 ~ 8 @ f5.6 ~ 4 @ f8 ~ 2 @ f11

While the aperture opening and shutter speed vary considerably, all of these combinations result in the same exposure level. The correct exposure amount will be determined by the metering system in your camera.

The creative aspect mentioned earlier comes in play by understanding how the various F-Stops and Shutter Speeds affect your image. The F-Stops control depth of field as explained in our recent blog post about apertures. The Shutter Speeds will affect your image by either freezing or blurring the image. A fast Shutter Speed such as 1/500 will freeze a race car or a galloping horse, while a slower speed such as 1/15 will create a sense of motion as the subject is moving faster than the shutter takes to complete its cycle. Practicing with your camera and tracking your results will allow you to begin building an understanding of how your Shutter Speed and F-Stop settings will affect the outcome of your image.