Why does a photo taken with a 200 mm lens look so different from one taken with a 24 mm lens? It’s simple: the focal length and angle of view determine how much of the world fits into your photo, how much to the right and left of you still slips into the picture – and how close or far away it appears. In this article, I’ll explain this in clear language, with practical examples and a little maths (don’t worry, it won’t hurt).
What exactly is focal length?
The focal length is simply the distance between the optical centre of your lens and the sensor of your camera – measured in millimetres.
Typical focal length ranges:
- Wide angle: 16–35 mm – lots in the picture, big impact.
- Normal focal length: approx. 50 mm – corresponds roughly to natural vision.
- Telephoto lens: 200 mm and above – brings distant subjects closer.
Image angle – your “window to the world”
The angle of view is the angle that your lens “sees”. Long focal length = narrow angle of view. Short focal length = wide angle of view.
The angle of view is the angle that your lens “sees”. Long focal length = narrow angle of view. Short focal length = wide angle of view.
Practical tip: If you want to “get more in the frame” (e.g. in confined spaces), use a wide-angle lens. If you want to compress the background or hide distracting elements, use a telephoto lens.
However, the focal length is more commonly used than the angle of view. But this is where confusion arises again. A 50 mm lens on a full-frame camera delivers a different angle of view than a 50 mm lens on a camera with a small APS-C sensor. (Incidentally, the size of the sensor says nothing about the quality of the photo!) If you use the 50 mm lens with an APS-C sensor, you have to add an extension factor, the so-called crop factor, of 1.5 (e.g. Sony, Fujifilm) or 1.6 (Canon). 50 mm on ASP-C then corresponds to a 75 mm focal length on a full-frame camera.
Comparison of typical focal lengths
| Focal length | Image angle | Typical use |
|---|---|---|
| 16 mm | 96° | Landscape, architecture |
| 35 mm | 63° | Reportage, Street |
| 85 mm | 28° | Portrait |
| 200 mm | 12° | Sport, Wildlife |
Wide angle vs. telephoto – which is right for your subject?
Wide angle: Enhances perspectives, makes the foreground large and dramatic. Ideal for architecture, landscapes or creative close-ups.
Telephoto: Compresses the background, brings distant subjects closer. Perfect for portraits, sports and wildlife.
It is often claimed that a telephoto lens brings objects closer together. Strictly speaking, this is not true. If the resolution of the photo were high enough, I could also crop the section I photographed with 200 mm from the image taken with 17 mm. The image contains exactly the same information; it is just significantly smaller in a wide-angle shot. The only thing that changes is my position in relation to the object.
Experiment
Take a piece of cardboard and cut out a rectangle the size of the camera sensor (full frame 36 x 24 mm, ASP-C approx. 23 x 15 mm). When you look through the cut-out, you will notice that the closer the card is to your eye, i.e. the shorter the distance, the more of the surroundings you can see. If, on the other hand, you hold the cardboard further away, the angle of view becomes narrower and you only see a smaller section. This is exactly what happens with different focal lengths.
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- 17mm f/8
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- 20mm f/8
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- 24mm f/8
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- 35mm f/8
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- 50mm f/8
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- 70mm f/8
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- 100mm f/8
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- 135mm f/8
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- 200mm f/8
Practical tips for choosing your lens
- Focal length is important – but the distance to the subject also has a significant impact on the image.
- Use the equipment you have and consciously try out different distances and perspectives.
- You can find more information about the different types of lenses in my lens
Conclusion – Understand focal length, take better photos
Once you understand focal length and angle of view, you can control how your image looks. Play around with different lenses, change the distance, try out unfamiliar things.
