Portraits and focal length

[Doug Kerr]

I had written about this a while ago, but I thought it might be apt to repeat it.

It is part of the "common wisdom" of photography that when doing portraits we must be careful not to "use too small a focal length" lest the resulting "perspective distortion" makes for an unattractive portrait.

But we need to remember that it is not the focal length of the lens that affects the "perspective". Rather it is the distance from the camera to the subject.

How focal length gets into the matter is this: if for some reason we should want to place the camera relatively close to the subject, then to get the proper framing we will be led to use a lens with a relatively small focal length.

Said the other way to, if we for some reason choose a relatively small focal length, then to get the proper framing we will need to have the camera fairly close to the subject, and it is this that leads to the "perspective" that may be unattractive.

Note that there is not any "distortion" really involved here. The image obtained with the camera fairly close to the subject is essentially exactly what a human eye, at that vantage point, would see. It's just that if we happen to view a person's face from "close up", our wondrous perceptual system "understands" the perspective involved, and does not take the view to be "distorted". But if we take a shot with the camera at such a position, and then a viewer sees it on a print or screen, the perceptual system is not "thinking in terms of" the view being from close to the subject.

Best regards,

Doug

 

[Ted Cousins]

I had written about this a while ago, but I thought it might be apt to repeat it.

It is part of the "common wisdom" of photography that when doing portraits we must be careful not to "use too small a focal length" lest the resulting "perspective distortion" makes for an unattractive portrait. ... <>

Hello Doug,

I've also read that the "ideal" focal length for portraiture is around 85 mm or so ...

Is there rational for that choice? ...

 

[Doug Kerr]

Hi, Ted,

Hello Doug,

I've also read that the "ideal" focal length for portraiture is around 85 mm or so ...

Is there rational for that choice? ...

My guess (and it is only that) is that with that focal length one will typically place the camera at a distance that results in a perspective leading to a presentation that is typically considered "pleasing".

Best regards,

Doug

 

[Doug Kerr]

Hi, Ted,

Certainly actual portrait photographers will have more insight into this than I.

My guess is that a focal length of 85 mm (ff35 equivalent) would lead to a camera position (to attain appropriate "framing") far enough from the subject to give the "perspective projection" we consider "natural".

Perhaps greater focal lengths would not further improve the "perspective" and would lead to having to have the camera so far from the subject as to not be "handy" in the typical studio.

Maybe.

Best regards,

Doug

 

[Jerome Marot]

Actually, it depends on the kind of portrait one wants to take.

The rule is basically:
-check what distance you fill comfortable with other human beings
-use the focal length which frame what you want.

In practice, it will be about 85 mm for a headshot with shoulders, but about 50mm if you want a full torso and a bit more if you want just the head.

Note that "distance you fill comfortable with other human beings" is a cultural construct, so cultures where people tend to be closer to another when talking may use shorter focal lengths. Conversely, interpersonal distance is a sign of social status and that may explain why fashion photographers like longer focal lengths: by moving away from the model, they get the perspective that we unconsciously assign to people with higher social status.

This is also used in movies and, because the moving picture distract us, the perspective can be used to its full effect. The French "nouvelle vague" with Jean-Luc Godard used relatively short focal lengths on a handheld camera (amongst other effects) to convey a sense of intimacy with the actors.

 

[Doug Kerr]

Hi, Jérôme,

Thanks for that. Very helpful.

Best regards,

Doug