© 2008 Wazari Wazir | Little Fingers | Using Depth of Field Creatively
Depth of field (DOF) by definition is the amount of your image that’s in focus or in another words is the distance in front and beyond the object that is in focus or sharp. There is a long discussing about depth of field on the internet, most of the discussion is more towards technical aspect of it rather than how you can use creative depth of field to your advantage.
To make it easy for you, there are three things that will affect the depth of field, those thing are the size of Aperture that you use, the Distance between you and the subject and also the type of Lens that you are using. This three things will affect your depth of field in term of sharpness or the area in your picture that will be in focus.
If you want greater depth of field, wanted everything to be in focus or sharp such as in landscape photography, you should use smaller Aperture, in the range of f/8 and above, using this aperture will guarantee you to have sharp image across the frame. There is also a “Sweet Spot” or a range in their aperture where they work at their best and produce the sharpest images, which is not necessarily by using the smallest aperture that your lens have and this “sweet spot” vary from lens to lens.
On the other hand if you want to have shallow depth of field, if you only wanted certain part of your image within the frame to be in focus or you wanted to make something stand out, just like my photograph above where only the little fingers of my son are sharp and leaving the face out of focus, you should use large aperture, like f/2.8 or below.
The second thing that will affect the amount of depth of field in your photograph is the distance between you and the subject. The closer you are to the subject, the shorter the DOF and subject at a greater distance will have greater depth of field than a close-up subject. That’s why in macro photography only certain part of the image are pin sharp while the rest of the picture or the subject is completely out of focus even though your lens and the subject is so close and on the other hand in landscape photography where the subject like a mountain can be a distance away but they appear to be sharp all across the frame.
The last thing that will affect the depth of field is the lens factor. A wide angle lens has much greater DOF than a telephoto lens. For an example you will get a very sharp image using 10mm lens at f/4 compared to using 600mm lens and shooting at the same aperture f/4. You might be wondering why you can’t get a “Bokeh” like 600mm lens have when using 10mm lens at f/4. They are in different category and that’s why the choice of lens will affect the depth of field regardless of your aperture and a combination of those three things will affect your DOF generally.
Understanding about Depth of Field alone will not make you a better photographer, instead you should know how to use it to you advantage or how to use it creatively. The question is how you can use Depth of Field knowledge to your advantage? Now you know that using wide angle lens will get you greater depth of field compared to using Telephoto Lens, so with this knowledge, you should invest yourself for Wide Angle lens if landscape photography or architectural photography is your main interest and on the other hand if you like to shoot wild animals or sports or portraiture you should invest in Telephoto Lens because this lens will help to isolate the subject from the background better.
If you decided not to buy any new lens at the moment, then you still can control your depth of field by the Aperture that you use or the distance between you and the subject, for an example, lets say that you only have a Kit Lens on your camera body which is 18-70mm or any length that comes with your camera body (entry level DSLR ) and you wanted to take a picture of your child playing in the park and want to have nice blur background, how you do that?
Very simple first open up the aperture to its widest setting, maybe f/4 or f/3.5 and then make sure that the distance betwen you and your child is closer, and if possible at its minimum focusing distance that the lens allow you, make sure also that the background is quite far away from your child, maybe ten to twenty feet away. Then just shoot, you will be able to get a nice blur background that is good enough to separated your subject from the background, you will be able to make your subject stand out from the background, even though the “Bokeh” is not as good as shooting with telephoto lens at its widest setting, you still get the job done which is emphasize the focus more on your subject by making it sharper from the rest.
In photography, there will always a point of interest, be it landscape or portrait photography. For portraiture, normally the point of interest is on the eyes so make sure you point your focus point on the eye especially if you are using Telephoto lens because they have a very shallow depth of field. If you focus on the nose, then the eye will be out of focus unless you have a very good reason why you wanted to focus on the nose in the first place, maybe they have a certain characteristic or unique nose rings that you wanted to highlight, then please do so.
When you know how to control depth of field, now it is up to you to use it creatively. You don’t need to buy new lens to get better depth of field if you know the principles but no doubt that certain lens will help you control depth of field more effectively. For an example having 24-70mm f2.8 will have bigger advantage than owning 18-200mm f/3.5 – 5.6. If you use 24mm at f2.8, you will be able to isolate the background better than using 18mm at f/3.5 because big aperture yield very shallow depth of field compared to small aperture like f/3.5, the numbers may not look much difference but they are.
There is more in photography than about depth of field DOF, having great understanding about DOF will never make you a better photographer, will never transform your photograph from bad to great but how you use DOF creatively that matters. Same like it is not so difficult to learn how to use a DSLR but how you use the camera that matters. Even a child can use a DSLR to take a picture if you show them which button they need to press but then again, knowing which button to press is not good enough to produce a great picture.