Thursday, August 23, 2012

Tutorial: Shallow Depth of Field

A shallow depth of field in photography 
has the effect of making your subject pop 
because the subject will be clear and stand out
against a blurred background. 

Canon 50mm f/1.8 lens
ISO 125, 1/200 sec, f/1.8

Canon 70-200mm f/2.8 lens
ISO 200, 1/80 sec, f/3.5 at 120mm (190mm equivalent)

This effect can be achieved in a couple of ways. 
We'll go from least to most technical.

1. Least Technical: Subject Placement
You can begin 
by keeping the subject as far away from a background as possible. 
The further away the background is from the subject, the easier it is to blur it out. 
It is not always possible to move the subject 
but keep this in mind when you experiment. 

2. A Tad Technical: Zoom In
Next, ZOOM! 
Stand further away from the subject and zoom into it. 
Not only will the help minimize facial distortion from being too close 
it also creates a shallow depth of field.

You knew it was coming....
technical basics:

In both cases, 
you will want to use the largest aperture possible. 
(Aperture is the opening in your lens, 
measured numerically in 'f-stops')
This is because the larger the aperture setting (f-stop), 
the more shallow the depth of field. 
Every lens has aperture settings.
Check your lens by reading the numbers on the front of it.
In the case below, the largest aperture is f3.5 when at 18mm (not zoomed in),
and is f/5.6 when zoomed in at 55mm.

Above: This is typical of cheaper lenses, 
a more expensive lens will maintain an aperture of f/2.8 throughout the zoom process. 
Non-zoom lenses can open wider that f/2.8.

The tricky part is, 
the larger the aperture (lens opening) the smaller the aperture number.
As shown below, f/2.8 is a larger opening than f/11.

3. A Bit More Technical:
Use the Portrait Mode
You will need to take the camera off Auto, 
but this is still pretty easy.
Choose the Portrait Mode setting on your camera. 
Portrait Mode tells the camera to use 
a shallow depth of field and will select the other settings accordingly 
to achieve proper exposure.



4. Semi-Technical: 
Use Aperture Priority Setting 

If your camera has it,
instead of switching to Portrait Mode, 
use the same dial to select Aperture Mode (A or Av.) 
In aperture mode you tell the camera to select a certain size lens opening 
and the camera will select the other settings accordingly 
to achieve proper exposure. 

For a shallow depth of field
select the smallest number you can achieve with your lens/camera.
You change the aperture selections
by using the a dial on your camera.
Each camera is a little different.

A great little exercise is to set up a subject against a background...
perhaps a flower.
Keep the camera in the same location, use a tripod if you have one.
Select Aperture Priority in the semi automatic settings.
Choose the largest aperture by dialing the aperture control dial. 
Take a photo.
Select the next aperture setting, one step smaller opening. 
Take a photo.
Select the next aperture setting, one step smaller opening.
Take a photo.
Select the next aperture setting, one step smaller opening.
Take a photo.

Keep doing that
then look at all of your images.
Take note of the effect the aperture setting has on your background.
If your aperture is f/5.6
the background will be more blurry than if your aperture is f/16

5. Buying A Lens
Selecting a large aperture opening
is the most common way to attain a shallow depth of field.
Each lens has different aperture settings.
The larger the aperture opens 
the more shallow the depth of field you can obtain,
but the more expensive the lens.

However, if you have a Canon DSLR
there is a nifty little lens that isn't too expensive compared to others.
It is the 50mm f/1.8 lens.
It does not zoom
but the depth of field is potentially much more shallow than
 the lens that came with your camera.
It is a great starting point for Canon users.
(PS. The top photo was taken with this lens.)

This tutorial was originally published at
Friday My Town Shoot Out.

No comments: