Aperture and Depth of Field

In photography, one tool that can help make boring images into fantastic photographs is aperture. Aperture. Aperture refers to the size of the diaphragm in your lens, and is one of three basic features that controls an image's exposure. However, in this particular section, I'll tell you how aperture controls the Depth of Field (DOF).

Depth of field just refers to how much of your photo is in focus, and there is a shallow depth of field, and an expansive depth of field.

In shallow depth of field, and object (mainly the main subject) is in focus, while the background is all blurry. You've probably seen many photos that have shallow depth of field, and they really can make any subject look wonderful!

In expansive depth of field, the whole frame is mostly in focus. By looking at an expansive depth of field image, you can know exactly what is in the background, everything is sharp and clear. You've probably seen many of these as well, they are very common when shooting landscape photos and can really make a great photo!

Below are some examples of the different depth of fields:

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This image above of the paints are a good example of a shallow depth of field. It's easy to tell because the focus is on the tips and the actual paint, while the background is all blurry. 

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Above is a good example of an expansive depth of field. You can tell that it's expansive because you can see how clear and in-focus the entire photograph is, and there are no areas in this photo that is blurry. 

Now aperture is a little tricky to understand at first, but the more you work with it, the easier it becomes. 

Aperture is measured in something called "f/stops". If you look on your DSLR camera, you'll most likely see numbers like f/5.6, f/22, and f/8. Now there are many more f/stops than the examples here, these are just shown to show you how they will appear on your camera. Aperture determines how much light can enter and fall onto the image sensor. The bigger the opening in aperture, the more light can come in. 

Now here's the tricky part: The wider the aperture, the smaller the f/stop number. Likewise, the smaller the f/stop number, the wider the opening is.

So, if you have a small f/stop number like f/5.6, then your aperture (the opening) is a pretty good size. However, if you have a large f/stop number like f/22, then you have a pretty small aperture (opening). Now this took me forever to get use to, and sometimes I still do have to think a little about which one is which, so don't worry if you're a little confused! 

Now that we know how to make sure our aperture is the size we want it by using f/stops, it's time to apply the aperture size to the depth of field. 

Now the wider your aperture, the more shallow depth of field you will get. Please notice that this is referring to aperture, not f/stops. If we had a big f/stop, then there would be a small aperture.

Likewise, the more narrow your aperture, the more expansive your photo will be.

So, if you want an expansive depth of field, the you will want the set your aperture to, lets say, a stop of f/22 just for example. Since this is a big f/stop number, that will make the aperture very narrow. And as we just learned, the more narrow your aperture is, the more expansive your depth of field will be. It's very important you understand the difference between aperture and f/stops because they both play such a huge role in photography! 

Below is a chart that may help you understand the relationship between f/stops, apertures, and depth of field: 

 

Vogel, Rex. "Exposure Traingle: Aperture and Depth of Field." Vogel Talks RVing. WordPress, 13 Jul 2013. Web. 15 Dec 2013. <Mclaughlin, Lauren. Austin Texas Wedding Photographer. WordPress, 9 Jun 2013. Web. 15 Dec 2013. . >.

 

Mclaughlin, Lauren. Austin Texas Wedding Photographer. WordPress, 9 Jun 2013. Web. 15 Dec 2013. <http://www.lmaustintexasweddingphotographer.com/category/austin-texas-photography/>.

I hope that these charts help you as much as they helped me with aperture, f/stop and depth of field!

Aperture can make such a big difference in your photos! Here's an example below of the different depth of fields on the same subject:

Now, you can control your aperture manually, however I cannot tell you how to do it for your camera because my camera could be much more different than yours, so be sure to read your manual!! But, I will show you how I can control my aperture with my camera.

My camera is a Nikon D3000 and to change the aperture on this camera, I first switch the dial onto "A". If you're not sure how to switch your dial, here's a photo of one below:

  

In the photo above, the setting is set on "P", but to change your aperture manually, you'll want to set it to "A".

 Now that you have it set on the setting to change the aperture, you need to change your f/stop number the way you want it. To do this, just slide the switch left or right. This "switch" is located on the back of your camera, near the LCD screen. In fact if you look into the photo above, you can see it. It's directly beside the "AF-L" button. However, here's another picture below to show you exactly what it looks like:

Now when you slide this switch back and fourth, you will see your f/stop numbers changing on your LCD screen. Once you've set your f/stop, all you have to do is take your photo!

I hope this has helped!