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By Eugene Struthers

By Eugene Struthers

Definition:- Depth of field is the zone of acceptable sharp focus in front of and behind the subject. It allows us to determine if the foreground and background are rendered as a soft blur or with distinct detail.



Depth of field extends one-third in front of the plane of sharp focus and two thirds behind it.


Focal plane

Focus distance

Depth of field


Depth of field


Focus point

Out of focus


Out of focus


Focus point

Models eye

Plane of

sharp focus

In focus





                                                                                                      Lens                                                                      Model


                       Image sensor                                                                           

                                                                                                                                      Focus point




                                                                                                                   Going into focus                                                      Going

                                                                                                                                                                                                         out of






                                                                                                                                   Depth of field                          



                                                                                                                                                              1                  Dof              2






                                                                                                                                                                       Depth of field​   


How will understanding depth of field improve my images?


The process of capturing images isn't that straightforward. Especially in the glamour photography sector. There may be certain situations, where you are unable to control your working environment and may rely heavily on technique to make the shoot a success. Knowing to carefully create sharp images whilst also having the ability to create out-of-focus backgrounds deliberately is a skill. It gives you greater artistic creativity. Especially in the glamour & nude photography field. 

Depth of field decreases with increasing focal length of the lens, if subject distance stays the same


              More                              Less Depth of field
              Focal length



              Less                                More Depth of field
              Focal length

Two main types                Distance Effects DoF


Shallow DoF                              Closer subjects

  • Only subject in                   Less DoF

       focus                                    Shallow 

  • f/2, f/2.8, f/4                     


Deep DoF                                   Distance subjects

  • Everything in focus            Greater DoF

  • f/11, f/16, f/22                     Deep


You can adjust the DoF by changing your distance from the subject.
Note that it affects your composition



Narrow Angle 


of view

Wide Angle 


of view

Digital sensor

Digital sensor

Shorter focal length

Longer focal length





Want to learn more about Focal lengths

Click here: Focal lengths

The focal length of the lens is the distance between the lens and the image sensor when the subject is in focus, usually stated in millimeters (e.g., 28 mm, 50 mm, or 100 mm). In the case of zoom lenses, both the minimum and maximum focal lengths are stated, for example 18–55 mm.

Changing the aperture is a way to adjust the DoF without affecting your composition. large (Wider) aperture in a shallower depth of field.

Canon 60D

Focal length (mm): 35mm
Selected f-stop: f/2.8
Subject distance: 3 feet

Canon 60D

Focal length (mm): 35mm
Selected f-stop: f/11
Subject distance: 18 feet


Depth of field:  f/2.8

Near limit: 2.89 ft
Far limit: 3.12 ft
Total depth of field: 0.23ft

In front of subject 0.11 ft (48%)
Behind subject 0.12 (52%)

Hyperfocal distance: 74.9 ft
Circle of confusion; 0.019 mm

Depth of field extends from 
37.45 ft to infinity


Depth of field:  f/11

Near limit: 9.2 ft
Far limit: 414.7 ft
Total depth of field: 405.6ft
In front of subject 8.8 ft (2%)
Behind subject 396 (98%)
Hyperfocal distance: 18.8 ft
Circle of confusion; 0.019 mm
Depth of field extends from 
9.4 ft to infinity

 Depth of Field simulator​


Click here: Dof Simulator

Hyperfocal distance: The closest distance at which a lens can be focused while keeping objects at infinity acceptably sharp. When the lens is focused at this distance, all objects at distances from half of the hyperfocal distance out to infinity will be acceptably sharp.

Hyperfocal near limit: The distance between the camera and the first element that is considered to be acceptably sharp when focusing at the hyperfocal distance. 

Depth of field (DOF): The distance between the farthest and nearest points which are in acceptable focus. This can also be identified as the zone of acceptable sharpness in front of and behind the subject to which the lens is focused on. 

DOF near limit: The distance between the camera and the first element that is considered to be acceptably sharp.

DOF far limit: The distance between the camera and the furthest element that is considered to be acceptably sharp.

Depth of Field (DOF) In Front: Distance between the DoF Near Limit and the focus plane.

Depth of Field (DOF) Behind: Distance between the focus plane and the DoF Far Limit.

The hyperfocal distance is the distance at which you set the focus of a lens, and everything half that distance up to infinity will be in focus. For example, using an 35mm focal length lens on an APS-C sensor camera such as the Canon 60d with an aperture of f/11, you get a hyperfocal distance of 6.22 meters. Which means that if you set the lens to focus at 3.11 meters, anything from 3.11 meters all the way up to infinity will be in focus.

Click here: DOF calcualtor

In optics, a circle of confusion is an optical spot caused by a cone of light rays from a lens not coming to a perfect focus when imaging a point source. It is also known as disk of confusion, circle of indistinctness, blur circle, or blur spot.



In photography, the circle of confusion (CoC) is used to determine the depth of field, the part of an image that is acceptably sharp. A standard value of CoC is often associated with each image format, but the most appropriate value depends on visual acuity, viewing conditions, and the amount of enlargement. Usages in context include maximum permissible circle of confusion, circle of confusion diameter limit, and the circle of confusion criterion.

Real lenses do not focus all rays perfectly, so that even at best focus, a point is imaged as a spot rather than a point. The smallest such spot that a lens can produce is often referred to as the circle of least confusion.

On older lenses, you can calculate the hyperfocal distance by using the indicators on the barrel on the lens. To do this, simply line up the infinity mark with the f-stop you want to use and then look at the corresponding f-stop mark on the right-hand side of the scale to see how close your acceptable sharpness would be. The indicator mark (Solid white strip) will show you where to focus to achieve your hyperfocal distance range.


So on a 24mm lens, if we set our aperture to f/22, and move the infinity symbol over this aperture. The lens hyperfocal distance range will indicate that our hyperfocal focal distance will be 3 feet at f/22. So if we focus on your model at 3 feet away, your image will be sharp from 1.5 feet to infinity. 


If you focus on the hyperfocal distance, everything from half the hyperfocal distance to infinity will be in focus. The wider your lens, the greater will be your hyperfocal distance.

The depth of the preview button allows you to preview the aperture that you have selected. It does not work if you have your aperture set to the widest setting of your lens, i.e. a 50mm lens with an aperture of f/1.4. But if you were to select say f/8, you will hear a rushing movement noise from within your camera. If you look through the viewfinder, you will notice that your image starts to get darker. This is your aperture diaphragm closing down to your selected aperture, in this case, example f/8. The depth of the preview button closes down the aperture diaphragm of your lens to the aperture setting that you have dialled into your camera exposure setting. What this is doing is giving you a preview of what your image will look like at that particular depth of field setting f-aperture number. An important point to note is. The aperture diaphragm of your DSLR camera allows wide open until the actual exposure. 

Then the lens aperture closes down to the required f-aperture setting, when you actually take a picture. At any other time, the lens aperture is always open to give you the brightest possible preview image through the optical viewfinder. To make things more simple. All new DSLR cameras have a live preview mode on the back of the camera on the LCD screen. Once you press the depth of field button, you will then be able to actually see a preview of your depth of field at your chosen aperture setting. And this will be a preview of your actual final image. The live view option, also allows you to see a more brighter image compared to that of the preview through the viewfinder. The reason being, your camera will compensate for the lose of light by pushing in more light into the image, via its internal electronic mechanism sensor. This can make your preview image appear a little bit noisier.  If you are using one of the more modern DSLR camera's and don't use your depth of field preview button. You can assign it's function to perform another function like image stabilisation.

Bokeh comes from the Japanese word boke, which means "blur" or "haze", or boke-aji, the "blur quality." Bokeh is pronounced BOH-K? or BOH-kay.


It is defined as the soft out-of-focus effect of the background that a photographer will get when shooting a model, using a fast lens, at the widest aperture, such as f/2.8 or wider.


The basic requirements to achieve bokeh are a fast lens, a lens with an aperture of f/1.4, f/1.8, f/2.8.

If you don't have a fast lens, you can still achieve the bokeh effect, by increasing the distance between the background and your model. Also, try to shoot at the widest opening your lens will allow. Bokeh can also be achieved at apertures of f/4 and f/8

When to use shallow depth of field?


The use of a shallow depth of field is a great way to make your subject stand out from the background and is ideal for portrait photography. It enables you, as a photographer, to cut out your subject from any given background. Making them the main focus of attention. In environments of low light situations, an increase in aperture will give you more light whilst also increasing the shutter speed. Ideal if you plan on photographing an all-topless female football match and need to freeze the action.


When to use a deeper depth of field?


The rule of thumb is if you need to get everything in your scene in focus. To obtain a deeper depth of field and get your whole scene in focus, use a wide-angle lens and a small aperture. 


How can you determine the depth of field?


The most common way is by using an application that you can download for free onto your smartphone. Most of the applications are free and simple to use. If you are not into using these types of applications. Then I would recommend going old school, and just using the depth of field preview button and live view on the back of your camera. Depth of field will eventually become second nature to you, capturing images in focus, and you will stop thinking about all the technical requirements. 

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