Depth-of-Field – Your Creative Tool
The creative use of Depth-of-Field (DOF) has been a journey of discovery, wonder and artistic joy for me my entire photographic career.
Even now, after many years of working with film, then digital cameras, it never ceases to amaze me what a huge difference the choice of how to use this technique makes to a photograph.
Learning to use DOF creatively to generate artistic impressions of the scenes and subjects you deal with is one of the most exciting discoveries you will have in photography.
Depth-of-Field is described as the distance within which everything is in focus. Think of having everything from 2 metres away to 10 metres away in focus, and nothing else; those 8 metres are the depth-of-field.
DOF is dependent on the aperture, focal length of your lens, distance the camera is from the subject and distance between the subject and the background.
Aperture, the opening in the lens, is measured in f/stops; the smaller the aperture, the larger the f/stop is numbered. For example, f/22 is a very small opening while f/2.8 has the lens almost completely opened.
Lenses with shorter focal lengths allow for a greater DOF than do longer focal lengths; the reason landscape photographers use wide angle lenses and hyperfocal distance in their work. This way they get the detail in the foreground in focus as well as the trees and hills in the background.
Hyperfocal distance is the closest distance you can be focus and still keep objects at infinity in acceptable sharpness. It changes with different f/stops.
Set your digital camera on aperture priority or use it in manual mode to gain control of the f/stop.
Using small apertures cuts the amount of light travelling through the lens and creates a need for longer shutter speeds.
Use your tripod.
Let’s take a look at the opposite end of the DOF spectrum; having a very short distance in focus. Portraiture is one photographic style where this comes into play often.
The closer your subject is to you and the further away the background is from your subject, the easier it is to have your subject in sharp focus while allowing the background to go out of focus.
Shallow DOF can create an image where the beautiful face of your child is in sharp focus while the background is blurry. This effect makes the portrait stand out from everything else.
Wide angle lenses are not usually used for portraiture as you have to get in very close to your subject causing facial distortion, and even wide open they still have quite a wide DOF.
Focal lengths of 50 to 85 are the norm for portraiture, allowing some distance between you and your subject and providing the capacity for a minimal DOF so you can create that wonderful bokeh – the blurry out of focus area of your photo.
The quality of the bokeh differs with each lens, lighting situation and any sharp highlights that may be in the background.
The more blades a lens has to control aperture, the better the bokeh. Their shape and the opening they create also impact on how it is displayed.
Lenses with large apertures allow for the shortest DOF so can be very versatile in doing close-up work. The wider the f/stop, the easier to separate the background from the item you want enhanced.
Longer lenses offer an opportunity to create a portrait while you are still some distance away from your subject. They may, however, cause some distortion.
However, long lenses are useful in photographing sports.
We’ve all seen the images of a football player making the great catch and it seems he is the only thing in the photo as the crowd and all the other players have been lost in the blurry background.
This is created with a very long lens and large aperture.
Take this information to use your digital camera to its utmost by experimenting with the creative use of depth-of-field. You won’t be disappointed.
If you have comments or questions post them in the comment section below.
I look forward to hearing from you.
Happy shooting and remember to leave the environment as you found it.
Norm Hamilton
normhamilton.ca/photography
norm@normhamilton.ca