We thought we’d post some tips on the most important elements effecting exposure:
Exposure means achieving the correct combination of three elements:
ISO Shutter Speed Aperture
Once you have correctly married together all three, you will achieve the right exposure, meaning the photograph will not be too light and not too dark. However, while shooting at night, for instance, you may intentionally wish for your photograph to appear dark or under exposed. While at other times you may wish for your photograph to appear too light or over exposed.
ISO
On your DSLR, the ISO setting controls the sensitivity of the camera’s image capturing cells. You can increase or decrease their sensitivity by lowering or raising the ISO number. On most cameras you will have the following range of ISO numbers:
100 – 200 – 400 – 800 – 1600 – 3200
100 is not very sensitive to light, meaning a lower ISO is suitable for brighter conditions. 3200 is very sensitive to light, meaning a high ISO is suitable for darker conditions.
But be warned, the higher the ISO the more degraded the image quality becomes. If image quality is important, you should try to avoid shooting on ISOs higher than 800.
SHUTTER SPEED
Shutter speed controls the duration of time that light is allowed to hit the camera’s light sensitive cells. Shutter speed is measured in fractions of seconds and usually a DSLR camera will have the following speeds:
SLOW MEDIUM FAST 1” – 1/2 – 1/3 – 1/4 – 1/8 – 1/15 – 1/30 – 1/60 – 1/125 – 1/250 – 1/500 – 1/1000 – 1/2000 – 1/3000
When you start to see a number with a after it, this means that the shutter speed is no longer in fractions of seconds, but in seconds. You should be able to scroll all the way from 1” (1 second) to 30” (30 seconds).However, shutter speed is also used to create two very different visual effects within your image: A slow shutter speed (1/60th sec and slower) will show more evidence of movement. A fast shutter speed (1/125th sec and faster) will start to freeze any movement.
APERTURE
While the shutter speed controls how LONG light is allowed into the camera, the aperture controls how MUCH light is allowed to enter the camera. Unlike your shutter speed, which is located in the camera’s body, the aperture is found in the lens.
Aperture is measured in F-Stops and on most DSLR cameras you will find the following range of F-Stops:
f2.8 – f3.3 – f3.5 – f4 – f4.5 – f5.0 – f5.6 – f6.3 – f7.1 – f8 – f9 – f10 – f11 – f13 – f14 – f16 – f18 – f20 – f22 – f32
Like your pupil, a camera’s aperture is a hole that gets larger (letting in more light) and smaller (letting in less light). You will see from the diagram below that the larger the hole, the smaller the number and vice versa:
REMEMBER: The bigger the number the smaller the hole The smaller the number the bigger the hole
DEPTH of FIELD
Similar to shutter speed, different F-stops give very different visual effects within the image. When using a small F-stop (f11 – f32), you will achieve a large depth of field, meaning all the image, from the very foreground to the very background, will be in focus. When using a large F-stop (f2.8 – f8) you will achieve a shallow depth of field, meaning only a very small slice of the image will be in fo- cus.
The effects of depth of field will be most evident when working in close up, or when you have some- thing very close to the camera (within 1 metre or so).
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