What is focal length and how can it improve your landscape photos?
It is important to understanding what focal length is and how you can effectively use it when you photograph. If you have an interchangeable lens camera system, you probably have more than one lens. I would guess one lens is a telephoto zoom.
Most beginners are intrigued by telephoto lenses where you can enlarge a distant subject without moving. With a zoom lens, you literally stand still in one place and photograph everything in a scene. This is great, isn’t it? You don’t have to move.
My first lens purchase was a telephoto zoom lens. I loved being able to use the camera as a binocular. At that time, I didn’t know much about composition.
As you learn landscape photography and how to create interesting compositions, you will soon find the telephoto lens might not be the best lens choice.
Why is focal length important in composition?
When you photograph landscapes one of the main goals is to create a sense of depth in the photo. You do this by including a foreground, middle ground and a background. A wide-angle lens is the best choice to achieve this. It’s no coincidence wide angle lenses are preferred by landscape photographers.
Comparing field of view between wide and telephoto lenses
Field of view is how much of the scene the lens sees. As the name suggest, a wide-angle lens has a wider field of view. You can modify the field of view by changing the focal length and the position of the camera. With a wide-angle lens, you can move very close to the foreground subject and still include a lot of the middle ground and background.
With a wide angle lens you're getting close to the background and the lens covers a lot of the background
Now, if you use a telephoto lens and want to include the same foreground in the frame, you must step back. You still fill the frame with the foreground subject, but you lose more of the middle and background. The scene is compressed, and the three-dimensional feel is gone. A telephoto lens has a narrow field of view.
With a telephoto lens you have to move back. The scene is compressed and the lens covers less of the background
Characteristics of wide angle focal lengths
- Exaggerate the relative size of foreground and background elements.
- Have a small minimum focusing distance allowing you to move close to the foreground. To get the exaggerated feel, you must position the camera very close to the foreground subject.
- Makes the background look smaller, but you see a lot more of it.
- Create an illusion of a greater than normal space around the foreground. You can use this to your advantage when you compose the photo. A slight change in camera position makes the foreground element move, relative to the background.
- Great Depth of Field.
Using a wide angle lens, the red flower seems huge compared to the background mountains
Characteristics of telephoto focal lengths
- Foreground elements seem compressed against background. The three-dimensional feel is perceived less compared to using a wide-angle lens
- A telephoto lens makes the background appear larger and shows less of the it in the frame
- It’s easier to isolate the subject when you use a telephoto lens
- With a telephoto lens, it’s more challenging to achieve sufficient Depth of Field
Using a telephoto lens, the dark green hillside behind the tree looks much closer than it actually is
Changing perspective is not about zooming the lens
When you change perspective, you change how the different elements in a scene relate to each other. This is important to create depth in the photos. Most beginners use their lenses without thinking of what changing focal length can do to the composition.
It’s a misconception you change the perspective when you zoom. When you zoom you just magnify the subjects in the frame by changing the field of view. The relation between the elements does not change. The only way to change perspective is to move the camera to a different position.
I took this video with an iPhone. I am very close to the flower (less than 30 cm). The flowers appear huge relative to the trees in the background. When I move the camera slightly, it has a significant impact on the foreground. The background change little. By moving the camera, I change the perspective. This way I can decide where I want to position the foreground flowers relative to the middle-ground a and the background. Sorry for the vertical filming, that’s not how you should film with an iPhone.
The switch from crop to full frame sensor camera
When you change from a crop-sensor camera to a full frame, the crop factor will influence on the field of view. A full frame sensor is 1,5 times larger compared to a Nikon crop sensor and 1,6 times larger than a Canon crop sensor. The difference in sensor size has impact on the focal length.
Because of the different sensor sizes, your 10mm wide angle lens on a crop sensor camera (Canon) has a field of view equivalent to a16mm lens. On the full-frame camera, the lens has a field of view as a 10mm.
Similar a 200mm lens has a focal length in 35mm equivalents of 320mm on the crop sensor camera and 200mm on the full frame.
With a telephoto lens, you will “loose” reach when you switch to full frame. On the wide end, the angle of view will increase which is an advantage for landscape phots.
The switch from phone or Point and Shoot to crop sensor camera
The lens of an iPhone 6 is equivalent to a 29mm lens on a full frame camera. 29mm is a reasonably wide angle lens. To achieve an effective field of view of 29mm in a camera with such a small sensor as in the iPhone 6, the real focal length of the lens is 4,15mm.
Because of this, the Depth of Filed in an iPhone is extreme. It’s virtually not possible to throw the background out of focus. The same applies to all camera with small sensors.
One of the consequences of this is when you switch from using iPhone to DSLR, you will experience it’s much more difficult to get the Depth of Filed you were used to with the phone camera.
For more info about which lenses to choose for landscape photography read here
Understanding what focal length is and what it can do to your photos is essential. The characteristics of wide angle lenses are perfect for landscape photography. You can create interesting compositions, and the Depth of Field is great, ensuring focus from foreground to background.