What Is Focal Length In Photography?

Experienced photographers and beginner photographers will work with focal lengths whenever they take photographs. It’s a core aspect of taking great, accurate pictures. Focal length in photography relates to distance between the lens and the sensor in a camera. As an example, a 100mm lens the distance between the glass and the sensor is 100mm.

Focal length in photography in a diagram:

Focal length definition

To offer a focal length definition, we would suggest:

Technically speaking, focal length is the distance between the point of convergence and the camera sensor, but we appreciate that’s not a particularly easy way to understand it. Instead, imagine a simple lens with one piece of glass focusing the light onto the sensor. The distance between the lens and the sensor is the focal distance.

How does focal length affect an image?

Focal length influences how your camera records a scene. It determines the angle of view, or how much of the scene ends up projected on the camera sensor. It controls how magnified an image looks, it influences the depth of field and can alter perspective, making objects look closer together or farther apart.

In summary, focal length affects images through three main ways:

1. Angle of view & magnification
2. Depth of field
3. Perspective

Angle of view & magnification

Short focal length lenses have a wide angle of view, hence the name “wide angle”. Longer focal lengths have a narrower angle of view, covering a smaller area of the scene. That’s why long focal length lenses seem to magnify the image - they capture a small part of the scene but still fill the sensor with it. A focal length of around 50mm is generally accepted as being about what our eyes see, which is why a 50mm lens is so often the standard lens that comes with the camera.

Depth of field

Depth of field, how much of the shot is in acceptable focus, changes with focal length. Shorter focal lengths not only capture a wider view, but they also have a deeper depth of field. They can capture almost everything from right in front of the camera to infinity in acceptable focus. As focal length increases the depth of field decreases, so a longer lens captures a narrower band in acceptable focus.

Perspective (in photography)

Perspective in photography is directly linked to focal length. Short focal lengths make objects look farther apart whilst longer lengths compress distances and make objects seem much closer together. Therefore, a wide-angle lens makes backgrounds seem far away whilst a telephoto lens brings them much closer.

Types Of Camera Lenses

You’ll probably have heard of a “wide angle lens” or “fisheye” lens; these are types of camera lenses that are commonly used in photography.

These are the main types of camera lenses, which we’ll go through one-by-one:

1. Ultra-wide/fisheye
2. Standard wide angle
3. Standard lens
4. Telephoto
5. Super-telephoto

Ultra-wide/fisheye

At 8mm to 24mm, an ultra-wide or “fisheye” lens captures a very wide angle of view, up to 180 degrees. This causes considerable distortion but captures a huge amount of the scene.

Standard wide angle

At 24 to 35mm, a standard wide angle lens means distortion is small – vertical lines may curve but can be corrected later. It’s good for journalistic and real estate work because the angle of view is huge and so much is in focus.

Standard Lens

At 35 to 75mm, the standard lens is suited to most subjects, from portrait to landscape. There is minimal distortion and can use large apertures down to f/1.8, etc. Good for portrait, nature, low light, and general use.

Telephoto

At 70mm to 200mm, a telephoto lens is able to pick out distant objects and fills the frame with a small part of the scene. The shallow depth of field is popular with portrait photographers because it throws the background out of focus. This lens is also used for general nature and wildlife work.

Super-telephoto

At 300 to 600mm+, a super-telephoto lens is mainly used in wildlife and sports photography where the subject is far away but needs to fill the frame.

Become a professional Photographer at the Institute of Creative Design

Learning how to take great photos is a life skill; even if you aren’t going on to become a professional photographer. If you are interested in being a professional, then you simply need to understand what focal lengths are best for which contexts and subjects. You’ll come back to this many times across your career!

If you are interested in learning about photography or becoming a professional Photographer, have a look at our industry-accredited courses.

FAQs

Is higher focal length better?

No, a higher focal length isn’t “better,” it just gives a narrower field of view and more magnification, making it ideal for distant subjects but less suited for wide scenes.

Why 50mm focal length?

A 50 mm focal length is popular because it closely matches the natural field of view of the human eye, offering a versatile balance for portraits, street, and everyday photography.

Should I get 50mm or 85mm?

You should get 50mm for versatility and everyday use. Get an 85mm for tighter framing and more background blur.

Why does every photographer need a 70-200mm lens?

A 70-200mm lens is often valued for its versatility. Photographers can capture their shots across portraits, sports and wildlife with this lens.