Many photographers who are just starting out have a hard time grasping and remembering how aperture and depth of field work. I have done a few posts on this before and will continue to as I think of various ways to describe it. While at a Detroit Tigers baseball game, my kids were playing with finger puppets. And it clicked – this was a great way to describe Depth of Field (not in technical terms but terms where I could even teach my 7 year old twins). As I explained it to them, they understood. So I know this is a simple way to explain.
While shooting, if your f-stop/aperture number is a low number (see here – f/2.2), you are shooting wide open. The closer to 1 – the more “wide” you are. Many lenses do not open to 1.2 or even 2.2. Prime lenses tend to open wider than zooms. In any case, the bigger your number (many lenses go to either f/16 or even f/22) you are stopped down.
So in simple terms, the wider you are (smaller numbers), the smaller your depth of field, smaller area is in focus. It also means more light is let in, but for this post, we will just cover what it means for what is in and out of focus. The larger the number, the larger the depth of field. More is in focus…
But there is more to the equation. Distance plays a HUGE role too. The closer you are to your subject and the further you are to a background, the greater the background blur (and the smaller the depth of field). The further you are away from your subject and the closer they are to the background, you get less background blur as the depth of field is greater. Let’s take a look at two shots below.
This 1st shot, I was at f 2.2. So very wide open. This was shot at my seats at a baseball game. My hand was extended by an arm’s length (very close – shallow DOF). And the background, stadium, was very far away. So given that I was so wide open, the background fell completely out of focus, to the point where it is unidentifiable.
In this second shot, the set up was the same, but I was at f/16. Subject still close to me. Background was far away. So while you usually would have your subject and background very much in focus when shooting at f/16, here it is not. You can faintly make out that sign that says Tigers and Comerica Park. But why is it blurry in the background? Because of the distance. Focus was about a foot and a half from the camera. Simply put, there would be no way to get the puppets and background in focus in this spot. This is not a bad thing – but maybe this will better help you understand how to shoot for your goals.
If I turned and had one of my daughters behind the puppets, the puppets would be in focus at f/2.2 and the background (my girls) slightly out of focus – even if a foot behind the puppets. They would not have looked like the 1st shot though as there would not be enough distance. If I shot my twins directly behind the puppets, focused on the puppets, at f/16, the puppets and my girls would both be in focus (as the depth of field would be large).
ASSIGNMENT: The best way to learn is by practicing!!! Please submit links to your DOF photo plays – shooting a few of the same basic shot wide open and stopped down – in the comment section. I hope to see lots of practice and plays!!! After you post – if you have questions, feel free to ask them along with your tries.Previous Post: WIN AN SLR LENS: Brand New Tamron Lens – 18-270mm or 28-300mm
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