The Truth About Lenses and Perspective
Have you ever stopped to think how you can control the perspective of your image? Many photographer think that a wide angle lens distort the perspective of an image. In this article we will see that focal length has nothing to do with distorting a subject, it is the camera to subject distance that determines perspective .To understands the relation between Lenses and Perspective, first we have to understand “Distortion”.
In photography, there are two types of distortions. Both results in some kind of deformation of images.
- Optical
- Perspective
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Optical Distortion :
In photography, distortion is generally referred to an optical distortion that deforms and bends physically straight lines and makes them appear curvy in images. In short, optical distortion is a lens error. Every lens to some extent suffers from optical distortion. We can rectify this error via ‘Image Editing Software’.
Perspective Distortion :
Another distortion type that is often seen in images is perspective distortion. Perspective distortion is caused by the position of the camera relative to the subject distance. Unlike optical distortion, it has nothing to do with lens optics and thus, it is not a lens error. Rather perspective distortion is the creative choice of a photographer. To capture images, photographer sometimes changes the perspective of the image to emphasize their subject.
A common example if you photograph a face with an ultra wide angle lens up close, their nose, eyes and lips can appear unrealistically large, while their ears can look extremely small or even completely disappear from the image. If the subject is too close to the camera, it can appear disproportionately large or distorted when compared to the objects in the background.
Look at the size of her head – it appears disproportionately large relative to her body. Its nose, eyes and lips are very much enlarged, while his ears are dwarfed.
Now I am going to discuss the most important and confusing topic. The relation between Perspective Distortion and Focal Length.
This is the part that seems to confuse a lot of photographers – the relationship of Foal Length to Perspective Distortion. You might hear some photographers say that one should use longer focal lengths to photograph people, or they will get distorted due to the lens’ short focal length (Wide Angle Lens). This is a mostly false statement, because lenses have no perspective. Other than fisheye lenses, all lenses have the same perspective.
It is the ‘Camera to Subject Distance’ that determines Perspective, not the ‘Focal Length’.
Let’s prove the fact:
If you stand in the same spot and use a zoom lens to shoot with different focal lengths, the perspective will remain the same. Take a look at the below comparison, shot at 24mm and 70mm focal lengths.
So if you take a 24mm lens and an 70mm lens, there is no difference in perspective between the two, as long as you stand in the same spot and keep the subject to camera distance the same. Yes, the subject would certainly appear smaller with the 24mm lens due to shorter focal length / wider field of view, but the perspective and proportions would be the same on both.
Focal Length affects how tight our subjects appear in the frame, but it does absolutely nothing to affect the Perspective.
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:
In the below example, the same subject captured at 24mm but from two different distances. At the right distance, the car appeared normal. But once we moved closer to the car, we saw the immediate effect of perspective distortion on the subject.
On the other hand what you see in the wide angle lenses, images stretches at the edge of a photograph; it is due to Optical Distortion of lens. Which create the illusion of Perspective Distortion at edges, but if you observe carefully the Optical distortion will reduce gradually at the centre of the image.
Conclusion :
To conclude, if you would like to control the perspective of our image, move closer or move away from the subject as per your test. Camera to subject distance can really reshape the aesthetics of your scene. And on top of that if you use ultra wide angle lens the perspective distortion will more accentuate (because of its high optical distortion).
If you stand in a same spot and use telephoto lens, it will compress the perspective but it never distort the perspective.
