One of the common misunderstandings in photography has to do with the focal length of a lens, or its optical distortion properties. Many photographers claim that a wider angle lens will distort facial features either because of the lens distortion, or the focal length of the lens being too short. In this article and the accompanying video (which is extracted from our upcoming Photography Life Basics Video), we will prove that focal length has nothing to do with distorting a subject’s face and the additional information on lens distortion will explain in detail exactly what gets impacted by lens distortion.
What is Face Distortion?
Before we discuss the impact of lens distortion and focal length, let’s first take a look at what face distortion is. While the word “distortion” here sounds similar to what we see on wide angle lenses that suffer from optical distortion, the two are not the same, as facial distortion is the result of perspective distortion, a phenomenon that occurs due to subject being too close to the camera. Take a look at the below subject, photographed with a short focal length lens at close distances:
We can see that in the first photo the subject is too close to the camera, which completely distorted his facial features – the face is stretched across the frame. In the vertical photo, the camera was moved away from the subject, which resulted in a lot less face distortion. However, the subject is still too close and the area outside the center frame is stretched heavily, causing the subject’s shoulders to appear very disproportional compared to the rest of the body.
While getting close to subjects can result in interesting and funny-looking photos like the ones above, this is not the way to photograph people normally.
Lens / Optical Distortion
Lens distortion, also known as “optical distortion” has nothing to do with perspective distortion mentioned above. Most lenses suffer from some type of optical distortion, but the particular offenders are wide angle lenses, which can show pronounced “barrel” distortion in images, as shown in a diagram below:
Seeing such distortion can easily trigger one to assume that facial distortion is caused by barrel distortion, since the effect is similar – the frame is stretched in a barrel fashion just like what one would see in the image samples above. However, that’s definitely not the case, because even lenses that exhibit the worst amount of barrel distortion won’t distort the subject as long as the subject is kept away from the camera.
Now, does this mean that optical distortion doesn’t play a role in distorting subjects? No, it sure does! If you use two similar focal length lenses with completely different distortion characteristics, the lens that exhibits more optical distortion will definitely make your subject appear more distorted. However, the effect is a lot less pronounced than you might think and can really only be seen at extreme close-ups. The effect of perspective distortion is far more substantial on a subject than optical distortion. For example, the Nikon 50mm f/1.4G suffers from approximately 1.4% barrel distortion, which can be easily seen when photographing anything with straight horizontal lines:
The barrel distortion on this lens practically does nothing in terms of introducing distortion to subjects. However, if the subject is placed at a very close distance, say if the subject’s face is tightly framed, we see two effects at the same time – perspective distortion and optical distortion, both of which are going to make your subject’s features appear slightly disproportional.
This leads us to focal length. Let’s take a look at what focal length does to our subjects in terms of distortion.
Focal Length
Focal length affects how tight our subjects appear in the frame, but it does absolutely nothing to affect the perspective. If you stand in the same spot and use a zoom lens to shoot at different focal lengths, the perspective will remain the same. This can be easily proven by photographing the same subject at different focal lengths, then analyzing the relative sizes of objects in the background. Take a look at the below comparison, shot at 24mm and 50mm focal lengths:
While the two different focal lengths resulted in differently framed images, the size of the subject relative to the background is the same. Here is the same image on the left, except this time it is cropped to have the same framing as the image on the right:
Note that using two completely different focal lengths also did nothing to distort the subject’s face or body, which proves that focal length has nothing to do with face distortion.
Take a look at another image, which I captured at 11mm on a full-frame camera (which is considered to be super wide), then tightly cropped:
At 11mm, if I placed the subjects at a very close distance to fill the frame or have similar framing as in the above image, they would appear extremely distorted. And yet at this particular distance and with this heavy of a crop, the subjects appear normal. This again proves that focal length has nothing to do with facial distortion!
To further solidify this concept, take a look at the below video:
https://www.youtube.com/watch?v=AiMxL1qfNE0
P.S. This video was extracted from our upcoming Photography Life Level 1 Basics video product, which we are planning to launch very soon. Since it was a more advanced topic, we decided to post it for our readers in this article.
In the video, we demonstrated that at the right distance, the model’s facial features appeared normal. But once we moved closer to the model, we saw the immediate effect of perspective distortion on the subject. Here is the same model at 35mm at two different distances:
We moved the camera, but the model remained in the same place. You can see a drastic change in the way her face appears in the two images, with the one on the right showing a much more stretched face, bigger nose and eye. Putting the two images together and aligning them reveals this drastic change in facial features:
This is something to expect when the subject is framed too closely with a wide angle lens.
Some people might argue that the focal length impacts distortion indirectly, because a wider lens requires one to get closer to the subject to keep the same framing on the subject. That’s definitely true, but that again has nothing to do with the focal length of a lens itself – it is the changed distance that causes such distortion issues. Here is another example, this time wih the subject framed the same, but captured at different focal lengths:
Now this is a classic case of perspective distortion – look at how going from 300mm to 14mm changed not only the perspective, but also the model’s facial features and her body.
