depth of field

Aperture and Depth of Field with Cherry Blossoms /  by Todd Henson

An example of aperture and depth of field with cherry blossoms.

One of the early concepts we learn as photographers is the relationship between aperture and depth of field. Aperture is the opening in the lens (or camera) that light travels through to reach the sensor or film. And with most lens/camera combinations you can adjust the size of this opening both to create the exposure you desire and based on the depth of field you desire for the photo.

Aperture

The aperture opening is measured in f-stops. I don’t want to get into too much technical detail with this post, but f-stops are represented with values like this: f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, etc. The smaller the number the larger the aperture opening. So f/1.4 has a much larger aperture opening that does f/22, meaning much more light can enter the camera. This affects exposure, but it also affects depth of field.

Depth of Field

The depth of field is the amount of the photo that is considered acceptably sharp, with everything outside the depth of field getting progressively less sharp or more blurry. When it comes to the relationship between aperture and depth of field, the larger the aperture opening (the smaller the f-stop value) the less depth of field, meaning less of the photo will be in focus. Conversely, the smaller the aperture opening (the larger the f-stop value) the more depth of field, meaning more of the photo will be in focus.

Cherry Blossom Examples

You can see an example of this in the photo at the top of the post and duplicated just below. The top portion of the photo has an aperture setting of f/3. You can see the background is very out of focus. The bottom portion has an aperture setting of f/16. You can see the background is still out of focus, but less so. Artistically, which do you prefer? There’s no right or wrong answer, just personal preference. And knowing how to adjust the aperture to give you the depth of field you want lets you be more creative with your photography.

The top half has an aperture opening of f/3 with shallower depth of field, the bottom half has an aperture opening of f/16 with more depth of field.

Click the images below to step through photos created with different aperture openings. Notice the differences in the look of the background, and even sometimes the foreground as the aperture opening gets larger, letting in more light but resulting in less depth of field.

Lens and Still Life Examples

And just to help demonstrate this further we’ll take a step away from cherry blossoms and look at an example using some still life subjects. First, below is an example of what the aperture in the lens actually looks like at different f/stop values using a 50mm lens.

And now take a look at the still life examples where a photo was created at each aperture shown above. Step through both the lens photos above and the still life below so you can see how changing the aperture opening affects depth of field.

I hope this was helpful to some of you. Aperture is a great creative tool we have, so go out there and use it.

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Choice of Aperture for a Clematis in the Garden /  by Todd Henson

A clematis in the garden (shot with an aperture of f/4).

One day while visiting my folks I was taken by the sight of this beautiful purple clematis flowering in their garden, hanging from a black metal trellis. Thankfully I had my camera with me that day, though only a single lens, the 16-35mm f/4. I don’t often use this lens for photographing flowers, but it seemed like a good time to start.

The photos in this post show 3 different angles I tried when photographing these lovely flowers. They weren’t all that high off the ground so I used the 35mm end of the zoom to focus in on the flower without too much distracting background. Then I experimented with framing and with aperture.

An example at aperture f/8.

An example at aperture f/4.

I most often use the 16-35mm when I’d like a lot of depth of field. Wide angle lenses are usually good at providing this. But when photographing these clematis I was more interested in a shallow depth of field. The widest aperture of this lens is f/4 and that ended up being the aperture I used for my favorite shots of this series. I did, however, create 2 images at f/8 to show you the difference this makes.

I held the lens physically close to the subject, probably very close to the minimum focusing distance of the lens. Even with an aperture of f/8 the background is nicely blurred, but it does still have some detail. Notice the difference when I opened the aperture one more stop to f/4, its widest setting. It throws the background even more out of focus, but it also throws some of the main flower out of focus.

An example at aperture f/8.

An example at aperture f/4.

There’s no right or wrong in these situations. It all depends on what look you are going for. For myself, I tend to prefer the images with a shallower depth of field. Which do you prefer?

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Fundamentals of Photography with John Greengo /  by Todd Henson

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Fundamentals of Photography with John Greengo. Image credit: CreativeLive

Fundamentals of Photography with John Greengo. Image credit: CreativeLive

Are you new to photography? Interested in learning how to master your new camera and use it to begin creating beautiful images? Or perhaps you already know a bit about photography and would like a refresher to reinforce various topics? If so, check out CreativeLive’s class, Fundamentals of Photography, taught by John Greengo.

For many years John Greengo has taught his Fundamentals of Photography class, often adding or updating content, especially if anything new has happened in the world of photography. I’ve purchased two versions of this class in the past (in 2010 and 2012), and still go back to the lessons from time to time. John is a great teacher and he creates amazing visuals that help explain and reinforce the topics he teaches. (The visuals and examples in this post are my own.)

Selection of SLR lenses

In the class, John covers a wide range of topics. He talks about the different types of cameras out there today and how each work. He explains each part of a camera system, including the digital sensor and the differences between sensors, and camera lenses in their different forms. He explains how light works and how the camera captures it.

John teaches about exposure, and how it is affected by choices of shutter speed, aperture, and ISO. He explains each of these topics with visuals that really help you grasp the concepts. Examples of this are how to use aperture to get a shallow depth of field or a large depth of field. He talks about how shutter speed will affect the look of your image, allowing you to freeze the action or create motion blur to show the action. He explains ISO and how it controls how sensitive the sensor is to light.

Example: Aperture and Depth of Field

The images of the lens below show the actual, physical, opening of the aperture at 4 different f-stops: f/1.4, f/4, f/8, and f/16. For this particular lens, a 50mm f/1.4 Nikkor lens, the largest opening possible is f/1.4 and the smallest opening possible is f/16. Click on the arrows on either side of the image to display to the next image.

The images of the frogs below show the depth of field for each of the apertures above. The depth of field is the area most in focus. In each image I focused on the eyes of the middle frog.

Notice at f/1.4 there is very little depth of field, meaning there is a lot of the image that is out of focus. Notice how at f/4, then f/8, and finally f/16, that more and more of the image is in focus.

Look at the images of the lens above again. Notice that f/1.4 is the largest opening and created the least depth of field (had the least in focus). Notice that f/16 is the smallest opening and created the largest depth of field (had the most in focus).

Example: Focal Length and Perspective

The images below were created at 2 different focal lengths. I attempted to keep the compositions as close as possible.

The first image was created using a wide angle lens at a focal length of 16mm. The front of the lens is very close to the foreground frog. Notice how large the foreground frog is in relation to the background frog. Notice how far away the background frog looks. Short focal length lenses (wide angle lenses) can stretch out the landscape, making objects in the foreground appear larger and making objects in the background appear smaller.

The second image was created using a telephoto lens at a focal length of 200mm. Notice how much larger the background frog is in relation to the foreground frog. Notice how much closer the background frog seems than in the wide angle image. This is called compression. Longer focal length lenses (telephoto lenses) compress the foreground and background, bringing the background objects closer to the foreground.

These images are an example of why it can still be very useful to move back and forth in a scene and not just rely on zooming your lens to fit the scene to the lens. Instead, visualize how you'd like the image to look.

Do you want to emphasize the foreground and minimize the background? Then use a wide angle lens and get close to the foreground object.

Do you want to emphasize the background, making it seem very large? Then use a telephoto lens. You can then move closer or further from the foreground object depending on how large you what that to be in the frame.

In addition to the more technical topics, John also talks about composition and design, about how to create pleasing images, how to add drama and evoke emotion in the viewer. He has had a long and successful career in photography, and has worked with other well known photographers, such as Art Wolfe. John is very good at taking what he’s learned and passing that on to his students through the videos and visuals.

Fundamentals of Photography is a long class full of content. It is first broadcast live over several days, usually close to 5 or 6 hours a day. One of the nice things about purchasing the class is being able to watch it later at your own pace. You can take one topic at a time, watch the videos, experiment with your camera, really understand the topic. Then move on to the next topic.

If you’re new to CreativeLive, check them out. They are an online education company that broadcasts classes on a whole range of topics. The classes are free to watch during the live broadcast and from time to time when they rebroadcast the class. They are always broadcasting something. If you like the class you can purchase it, letting you stream the class anytime, and also letting you download the videos and other content to your computer to watch offline anytime you want. Some classes have extra content only available when you purchase. I have purchased dozens of classes over the years, and likely will continue to. CreativeLive offers a fantastic platform for learning. Their topics cover not just photography & video, but also art & design, music & audio, craft & maker, and money & life.