Ep 202: A complete guide to focal Length, and how it affects focus and depth of field

A complete guide to focal length and how it affects focus and depth of field. This is a masterclass in one episode. So sit back and enjoy this ride into how the focal length of your lens can impact depth of field, focus and much more. Master this and it will be a game changer.

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Show Notes

A complete guide to focal length and how it affects focus and depth of field

  • The focal length you shoot in can be random (it just felt right) or deliberate. Many photographers find they tend to like how a particular focal length works for the subjects they shoot.
  • Documentary shooters often prefer working at 35mm-50mm because it allows them to get close to the action. The viewer feels like they are there.
  • Landscape and architecture looks good captured on a wide lens because it captures the sense of space in a location.
  • Portrait photography can be shot with any focal length.
  • The focal length used in a headshot will also influence the physical appearance of the person being photographed.
  • There are many examples online that show the difference a focal length will have on a face.
  • It’s worth noting that this is exaggerated at close proximity to the model.
  • Lens compression is caused by proximity not focal length.

The difference between wide and long is the:

  • Reach
  • Field of View
  • Focus
Above: Here is an image photographed at a focal length of 24mm and a distance of 5m from the model

 

Above: Here is the same image photographed at a focal length of 105mm and a distance of 5m from the model.

 

Above: If we crop in on the 24mm image and overlay the two images you can see that there is very little change in the shape of the face.

Focal length only distorts images due to proximity.

Above: A wider focal length or anything less than 35mm at close proximity will distort the features and makes the face appear narrower.

 

Above: A focal length of 50mm at close proximity has the least distortion and will give the most authentic representation of a person.

 

Above: As the focal length becomes longer you can see the face becomes fuller because longer lenses compress the facial features.
  • Knowing how a wider or longer focal length will impact the physical appearance of a person can be a useful way to decide on the most flattering focal length to choose.
  • As you can see in this example, the model naturally has a very narrow face and the focal length of 200mm gives him the most flattering portrait.
  • A person with a fuller face may prefer being photographed at a slightly wider focal length because this will give the face a narrower appearance.

Another important factor to consider when choosing a focal length is something called the angle of view

 

 

 

 

  • When shooting with wider lenses the angle of view or how much of the background is in frame is much greater than when shooting with a longer lens.
  • This is important information to know because it can drastically change the way you scout potential locations.
  • As you can see in these diagrams a wider lens will also give a wider angle of you or show more of the background.
  • A longer lens gives a narrower angle of view or shows less of the background.

Focal Length and Depth of Field

Depth of Field

  • A shallow depth of field is used when you want to isolate your subject from the background (portraits).
  • A large depth of field is used when you need every part of the frame in focus (products and landscapes)

A large aperture (small f-number) such as f/1.4 or f/2 will produce a short or shallow depth of field, while a small aperture (large f-number) such as f/11 or f/16 will give you focus over a longer distance.

Above: Depth of field or area of focus decreases when the aperture becomes larger
Above: The shorter the focal length the greater the depth of field

 

Above: The closer you are to your subject the shallower the depth of field (or area of focus)
If you want a shallower depth of field move your camera closer to your subject

Depth of Field is greater behind the point of focus than in front of it.

Group photos

Above: If you are focusing on a large group of people of say 15-25 focus ⅓ of the way in. Not front or middle of the group.
Above: If you are focusing on a large group of people of say 15-25 focus ⅓ of the way in. Not front or middle of the group.

 

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About Gina

About Gina

Gina Milicia is one of the most widely known and respected photographers in Australia. She is the master of capturing that ‘magical moment’... READ MORE

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