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Your lens is like the eye of the camera. Focal length and aperture determine the way it sees.
The effect of focal length is easier to see if you use prime lenses as there’s a dramatic difference when you change from one to another. For that reason it’s handy to think of a zoom lens as several focal lengths in one. For example, if you have an 18-55mm kit lens, you can think of it as three lenses with focal lengths of 18mm, 35mm and 55mm. Some zooms have important focal lengths marked on the barrel to help you with this.
That doesn’t mean you should ignore the in-between focal lengths. There are always times when they come in useful. But it will help you learn how those three important focal lengths work, and what the differences between them are.
In this example, the kit lens is a wide-angle lens at 18mm, a standard lens at 35mm and a short telephoto at 55mm. They behave differently, especially when it comes to composition. Understanding the relationship between focal length and composition, plus other elements like perspective and field of view, helps you choose the best one to use.
Lenses also have other characteristics that contribute to the look of the photo. One of these is bokeh, the aesthetic quality of the out of focus parts of the photo. Bokeh is affected by factors like the shape of the lens aperture and the quality of the lens elements. Some lenses, like the vintage Helios 58mm, are known for the distinctive character of their bokeh.
Focal length, aperture and composition
All these things influence your approach to composition. It’s always a good idea to ask yourself how to use the characteristics of your lenses to best effect. It’s about working work with your lenses rather than fighting against them.
For example, if you are using a telephoto lens is there a way you can use the compression effect (the way it magnifies the background and draws it closer to the subject) more creatively? As you learn more about your lenses you will become better at selecting the best one to create the effect that you want. Let’s look at some examples.
Sigma 50-150mm f2.8 lens (APS-C)
This is an APS-C zoom that I bought many years ago when I owned a Canon EOS 40D camera. I was working in the United States at the time and even thinking about that camera brings back memories from that time, when my life was completely different to what it is now.
I made the photo below with a focal length of 150mm and an aperture of f2.8 It was made in the city of Potosí, Bolivia.
The woman in the photo walked past me, turned a corner and was gone. I clicked the shutter as she turned and made this photo. It was dusk and the photo’s packed full of mood and atmosphere. It’s also a great example of the type of photo you can make with a telephoto lens. This is how the focal length and aperture affected the composition.
Narrow depth of field
The combination of wide aperture and long focal length means there isn’t much depth of field. Part of the background is out of focus which helps create separation between the woman and the buildings behind her.
Compressed perspective
The distance between the camera and the subject compress perspective, pulling the background close to the woman and baby. Combined with the moody lighting it creates a cinematic effect similar to that used in movies.
Narrow field of view
The telephoto lens has a narrow field of view and captures just part of the scene. This focal length is good for capturing detail, but not for including the entire scene.
Samyang 100mm macro lens (APS-C)
This is another APS-C lens that I use with my Fujifilm cameras to make photos of flowers. Here’s the sort of photo that you can make with it.
Narrow depth of field
Again, there isn’t much depth of field in the photo. Depth of field decreases as the subject gets closer to the camera, so narrow depth of field is always a feature of close-up photos. That’s often a benefit as it makes it easy to blur the background.
Compressed perspective
The compression effect pulls the flowers in the background closer to the flower I focused on. If I’d used a shorter focal length they would look further back and be smaller in the frame. There would be more green and less yellow. The way the 100mm macro fills the background with color is one of the reasons I like working with this lens.
Canon 85mm f1.8 lens (Full-frame)
I used an 85mm lens on a full-frame camera to make the natural light portrait below. I set the aperture to f2 to blur the background. This is a typical setting for portraits and a useful feature of prime lenses.
Narrow depth of field
This portrait has a shallow depth of field thanks to the wide aperture of f2. This helps separate the model from the background.
We made the portrait on a beach and I positioned the model in front of a white square somebody had painted on the cliff face. This created an interesting framing effect. The white square framed the model’s face, and the dark cliffs framed the square. The aperture choice, focal length and lighting worked together to make the result.
Compressed perspective
It’s harder to see in this photo as the background is out of focus, but the compression effect evident in the first two photos is also happening here.
Narrow field of view
The focal length may be shorter but there’s still a narrow field of view. The 85mm lens behaves in a similar way to the 150mm lens in this respect and you can’t see much of the background in the photo. This is another reason why an 85mm lens is such a good portrait lens.
Learn more: How to Shoot Beautiful Portraits in Natural Light
Fujinon 35mm f2 lens (APS-C)
I made the garden photo below using my 35mm lens, which is a standard or normal lens on my APS-C Fujifilm cameras.
Standard lenses occupy an interesting middle ground between telephotos and wide-angles. You can move in close and crop in tight to the subject, a bit like a telephoto lens. Or, like I did with the photo here, you can step back and include more of the scene in the photo, a bit like a wide-angle lens.
Depth of field
I set the aperture to f13 to get as much as the scene as possible in focus. I wanted both the house in the background and the branch at the top of the frame to be sharp.
Standard lenses are interesting. You can get close to your subject and use a wide aperture to throw the background out of focus. Or you can step back and stop down to make everything sharp. It’s another example of how versatile this focal length is.
Perspective
Standard lenses are said to have a perspective similar to that of the human eye. A photo made with a standard lens doesn’t have the compressed perspective of a telephoto or the exaggerated perspective of a wide-angle.
Field of view
The wider angle of view means that you can fit more of the scene into the frame compared with a telephoto lens. In this case that let me frame the house with the branch at the top and the white flowers in the foreground. Compare that to the previous images where you see far less of the subject’s environment.
Learn more: Three Reasons To Buy a Standard Lens For Your Camera
Fujinon 18mm f2 lens (APS-C)
I used an 18mm lens on my APS-C Fujifilm camera to create this landscape photo in northern Spain.
Wide depth of field
I used an aperture of f11 to get the entire scene in focus. This is different to the approach I used with in the earlier photos made with telephoto lenses, where I wanted the background to be out of focus. This time I wanted everything sharp, from the grass in the foreground to the horizon. Wide-angle lenses are ideal when you want lots of depth of field.
Perspective
Wide-angle lenses encourage you to get close to the subject, which has the effect of pushing the background into the distance and making it seem further away.
Field of view
The wider field of view of wide-angle lenses mean that you can fit much more of the scene in the photo. That’s one of the reasons wide-angle lenses are popular for landscape photography.
Learn more: How To Photograph People Using A Wide-Angle Lens For Travel Photography
Helios 58mm f2 lens (APS-C)
The Helios 58mm is a vintage, manual focus lens that you can use with most modern cameras using an adapter. It’s known for the swirly bokeh effect you get with the aperture wide open. You don’t get that effect with every photo, as it depends on what’s in the background (highlights help) and how far it is from the subject. But it still gives the bokeh an unusual look that a regular lens doesn’t give you. I used it fitted with a 500D close-up lens to make the photo below.
It’s a good example of how the optical qualities of the lens make a difference to the look and composition of the photo.
Further reading: The Creative Assignments ebooks
Hopefully the examples in this article help you understand how the focal length and aperture of your lenses affect the look of the photo. With practice you will learn how to select the best focal length and aperture to create the effect that you want.
A great way to motivate yourself to get the best from your lenses is to set yourself assignments – mini-briefs that encourage you go to out and put what you’ve learned into practice. That’s not as easy as it sounds, which is why I wrote my Creative Assignments books. Each one is filled with assignments and inspirational photos designed to spark your creativity and motivate you go to out and make beautiful photos. Click the link to find out more.
