Depth of Field
The simplest way to explain depth of field is the area of your image that is in focus. It's the distance between the closest and the farthest object that are in focus to the camera. The 'shallowness' or 'deepness' of the depth of field depends of the f/stop (also known as aperture), the focal length of the lens, the size of the camera sensor and distances between you, the subject and the background. Different depths of field are used depending on what photo you're taking. For instance, if you're focus is on somebody's face, you'd want a shallow depth of field so the background would blur not to distract the viewer from the face. On the other hand, you'd want a deep depth of field when taking shots of landscapes as tries to get everything in the shot in focus, so there's distance and depth to the image.
The smaller you set your aperture, the more depth of field you get and the more of your shot appears in focus.
Aperture
The aperture of a camera refers to the size of the iris (hole) within the lens. The bigger the hole, the more light gets into the camera. Aperture is measured in F-stops. A low number like F/1.8 or F/2.1 means a wider aperture. F/16 would be a smaller aperture. Therefore, for a shallow depth of field, you would have a wide aperture, giving more exposure to the image. In a deep depth of field you would have a small aperture giving less exposure to the image, with a high F number.
Here is an example of shallow and deep focus that I took whilst in Tenerife.
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| Deep: Depth of Field |
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| Shallow: Depth of Field |
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| Shallow depth of field |
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| Deep depth of field |
Shutter Speed
Shutter speed controls how quickly your camera takes the image (the exposure time). It's measure in fractions of a second such as 1/30th, 1/50th, 1/200th etc. The majority of people can't stay still for more than 1/30th of a second so if you're taking a photo of someone from the waist up, get them to spread their legs wider, giving their body more balance and stability, thus giving less blur to the image. The longer the shutter speed, the more light gets into the camera. A short shutter speed will freeze things without much motion, so you can photograph fast moving things like cars or animals. A long shutter speed would capture movement, and the image would look blurred. This is useful to show movement or speed. The F-number also affects shutter speed. Using a low F-number means more light is entering the lens, therefore the shutter doesn't need to stay open as long to make a correct exposure which translates into a faster shutter speed.
Again, the reverse is true: using a high f/stop means that less light is entering the lens and therefore the shutter will need to stay open a little longer which translates into a slower shutter speed. Here are some examples of me playing with shutter speed:
ISO
ISO is the level of light sensitivity of your camera. The lower the ISO , the less sensitive it is to the light,. The component within your camera that can change sensitivity is called “image sensor”, it's the most important (and most expensive) part of a camera and it is responsible for gathering light and transforming it into an image.
By increasing the ISO, your camera sensor can capture images in low-light environments without having to use a flash. But higher sensitivity comes at an expense – it adds grain or “noise” to the pictures.
Workshop Practical
In one of our workshops, we went around campus using the Nikon D7000 to play around the the settings, here are some of my results.
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