Photography, Photography Tips and Tricks

August 18, 2017

Shooting in Manual: Aperture

Earlier this summer, Caleb asked me to teach him how to shoot in manual mode.  He wanted to learn more about how the camera works, what the different settings do, and how changing settings would affect the photo.  The photo of Elizabeth below is one that Caleb took a few weeks ago on manual mode.   Not bad at all, right?!  I have been so impressed with how much Caleb has learned that I decided to write a series of blog posts teaching others how to do the same.  

Samantha Ludlow Photography, aperture, shoot in manual

The Exposure Triangle

There are three different elements that work together to determine an image’s exposure:  aperture, shutter speed, and ISO.  When shooting on manual mode, the photographer is in control of all three elements and adjusts them as needed to properly expose the image.  Increasing or decreasing one element will change the exposure.  So it’s important to understand each component and how they interact to create the final image.  I will devote an entire post to the exposure triangle at the end of this series, but first I want to focus on each individual component.  I’ve decided to start with aperture because it is responsible for creating the creamy blurry backgrounds that I love.  

What is Aperture? 

Simply defined, aperture is a hole or gap.  In a camera, it refers to the opening in the lens through which light passes into the camera.  If you were to think of the human eye, aperture would be like the pupil.  It can be wide open, or dilated, letting lots of light in.  Or it can be narrow, allowing only a tiny amount of light to pass.  

Samantha Ludlow Photography, aperture, shoot in manual

These three images illustrate how changing the aperture changes the amount of light that enters the camera. All of these images were taken with my 50mm lens and with the same shutter speed and ISO. In the top image, the wide aperture (f/2.2) allows a large amount of light into the camera, resulting in a bright image. The bottom image has a narrow aperture (f/11) and only a small amount of light can enter the camera, producing a darker image.

Aperture and Depth of Field

The amount of light that enters the camera plays a large role in determining depth of field.  Depth of field simply refers to how much of the photo is in focus.  A narrow depth of field has a very small portion of the image in focus, and everything before and behind will be blurry (or creamy as I like to call it).  A wide depth of field allows a larger portion of the image to be in focus.  

When the aperture is wide open, a large amount of light enters the camera and the depth of field is very narrow.  Conversely, when the aperture is narrow, only a small amount of light enters and the depth of field is very deep.  

So if you want a smooth, creamy background, pick a wider aperture!

These images illustrate how changing your aperture will affect the depth of field. The top image is shot with a wide aperture (f/1.4) and you can barely see any of the leaves behind the daisy because the depth of field is very narrow. The middle image was shot at a moderate aperture (f/4.5) and the leaves are starting to come into view. In the bottom image, a narrow aperture of f/11 keeps the entire frame in focus. (All three images were taken with my 50mm lens.)

Measuring Aperture

Aperture is measured in f/stops, which correspond to how wide the opening in the lens is.   The most important thing to remember when learning about f/stops is that the lower the number, the wider the lens diaphragm.  So f/2.8 has a wider opening than f/11. 

low f/stop number = wide opening = more light = shallow depth of field

high f/stop number = narrow opening = less light = wide depth of field

I love how this diagram from Cole’s Classroom brings all of the above information together!  

what is aperture

Testing it Out

Ok, so now you’ve learned all about aperture!  How can you test it out?  The easiest way is to set your camera on Aperture Priority Mode (“Av” if you shoot Canon, “A” for most other cameras).  In this mode, you are able to change the aperture and the camera will adjust the other two components so that your image is properly exposed.  I suggest finding a stationary object and photographing it multiple times, changing only the aperture.  See how different f/stops create different effects in the image!   

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