What is the best lens to take an accurate photo of the face with no distortion?

[bossman101]

I measure facial proportions and ratios for cosmetic procedures. i’ve noticed that using photos for this can be difficult as measurements can be extremely off due to lens distortion. What would be the best way of capturing the face, as it is, so that the measurements would be the same as measuring from the physical face itself?

A photography enthusiast friend of mine mentioned the Canon 85mm F1.2 lens, while others on the internet have said that the rear camera of a good phone will suffice, if the photo is taken from far enough of a distance. Could anyone confirm whether either statement is correct, and if not provide other recommendations to get the most accurate image possible?

Many thanks

 

[mjcmt]

50mm on full frame camera is considered most natural, but you'll have to get closer to the subject. 85mm compresses face a bit, but you can stand further from subject.
50mm lenses are also inexpensive.

 

[480sparky]

The longer, the better. A 'normal' lens requires the camera to be too close to the subject and will distort a face... the nose will be oversized and the ears look too small.

I'd go with a 300mm equivalent on a full-frame.

 

[smoke665]

Here's a good article with examples of how focal length affects facial distortion. Facial distortion of various focal lengths for headshots: Nikon SLR Lens Talk Forum: Digital Photography Review

 

[Rickbb]

The old standard for portraits is 85 to 105. Let's you get back a bit to not intimidate the sitter but does slightly flatten the FOV.

Camera phones tend to be wide angle and if you're going to do this for what you describe it may distort too much to be accurate.

Testing by shooting at scales/rulers at the distance you are going to use will help you decide.

 

[DanOstergren]

100mm would be my go-to for this. Any wider and you'll start getting distorted facial features the closer you are to the face.

 

[wfooshee]

The distortion comes from the distance from the lens to the subject, not from the lens itself. Very far away gives a rather flat image of the subject, very close exaggerates features closer to the camera, which is perceived as distortion. If you shot a 30mm lens from 5 feet away, and a 105mm lens from 15 feet away, the proportions of the subject's face will be the same, but obviously much smaller in the 30mm frame. What you have to do is find the perspective that is useful to you, then use the lens that gets you the right framing for the distance that gives you the perspective you want.

As has been stated a few times already, that is generally accepted to be a lens in the 85 to 105 mm range, on a full-frame camera, the popular range for portraiture. You don't want distortion, or excessive flatness, in portraits, so that's where that focal-length range comes from.

It may be that for your measurements, something flatter is required, which could put you into a much longer range lens to get a significantly higher camera-to-subject distance.

It will probably take some trial-and-error to find the subject distance that gives you the useful perspective you need. Again, the distortion or flatness comes from subject distance, not from the lens itself. When someone says a 30mm lens distorts too much, it's because to fill the frame with a face, you have to be too close to he subject.

 

[bossman101]

The distortion comes from the distance from the lens to the subject, not from the lens itself. Very far away gives a rather flat image of the subject, very close exaggerates features closer to the camera, which is perceived as distortion. If you shot a 30mm lens from 5 feet away, and a 105mm lens from 15 feet away, the proportions of the subject's face will be the same, but obviously much smaller in the 30mm frame. What you have to do is find the perspective that is useful to you, then use the lens that gets you the right framing for the distance that gives you the perspective you want.

As has been stated a few times already, that is generally accepted to be a lens in the 85 to 105 mm range, on a full-frame camera, the popular range for portraiture. You don't want distortion, or excessive flatness, in portraits, so that's where that focal-length range comes from.

It may be that for your measurements, something flatter is required, which could put you into a much longer range lens to get a significantly higher camera-to-subject distance.

It will probably take some trial-and-error to find the subject distance that gives you the useful perspective you need. Again, the distortion or flatness comes from subject distance, not from the lens itself. When someone says a 30mm lens distorts too much, it's because to fill the frame with a face, you have to be too close to he subject.

After asking numerous people, I keep getting the same two responses:

1. The higher the focal length, the more precise the photo will be. Others say focal length isn't that important, but distance is, and so a higher focal length lens will allow us to get a suitable distance (something like 5 metres away, for example)
2. A focal length between 70-100mm produces a natural image of the face. Going too low or two high can cause different types of distortion, as the image below suggests

I'm not sure if the image above is correct or not, so would appreciate advice on that. In that case, what would be the optimal distance to take a photo with an 85mm lens be?

 

[cgw]

Will getting this right reduce the ranks of plastic surgery victims? Just asking...

 

[AlanKlein]

85-135mm lenses. Here's neat DOF, angle of view, and field of view calculator.
Depth of Field (DoF), Angle of View, and Equivalent Lens Calculator • Points in Focus Photography{%22c%22:[{%22f%22:13,%22av%22:%228%22,%22fl%22:135,%22d%22:2624,%22cm%22:%220%22}],%22m%22:0}

 

[smoke665]

not sure if the image above is correct or not, so would appreciate advice on

Your example is somewhat misleading as Barrel and Pincusion are both part of the same type of distortion. On the left, Barrel Dstortion causes straight lines to curve outward, or inward (Pin Cushion), and is affected by lens design and FL. 50mm lens are relatively easy to design and are virtually free of this type of distortion. Shorter FLs have more barrel distortion while longer FLs have pin cushion.

Good portrait photographers use this knowledge to enhance or subtract from facial features. IE Thinning chubby cheeks, adding fill to hollow cheeks,.

The other kind of distortion is Perspective Distortion. The effect that objects closer appear larger while something farther away appears smaller. It is as others have mentioned dependent on POV. If you look at a face from X distance and it appears natural, then so should a photo. However you need to remember to actually look at the whole face (nose, eyes, ears, hair) because there's a tendency to only concentrate on one feature.

So to answer your question there is no one size fits all answer as it is dependent on lens design, desired FOV, FL, the acceptable amount of distortion, space available to setup, and POV. That might be anywhere from minimum focal distance to ????. The only way to answer that question is to set your camera on a fixed tripod and shoot different FLs test shots, move the tripod and repeat.

 

[Soocom1]

Ill chime in and point out that Barrel and pincushion are an affect of the lens construction itself.
There is very little to mitigate it out 100%.

Flat field lenses are designed to do this, and there have been several older styles for film cameras that can be adapted for mirrorless.
The lenses (especially the Vivitar Series 1 90-180 flat field) is IMO set up properly a serious contended for ultra low distortion.

but that's just my opinion.

 

[RAZKY]

I measure facial proportions and ratios for cosmetic procedures. i’ve noticed that using photos for this can be difficult as measurements can be extremely off due to lens distortion. What would be the best way of capturing the face, as it is, so that the measurements would be the same as measuring from the physical face itself?

A photography enthusiast friend of mine mentioned the Canon 85mm F1.2 lens, while others on the internet have said that the rear camera of a good phone will suffice, if the photo is taken from far enough of a distance. Could anyone confirm whether either statement is correct, and if not provide other recommendations to get the most accurate image possible?

Many thanks

I've not looked at this, but it may be worth a try: DOF simulator - Camera depth of field calculator with visual background blur and bokeh simulation.

 

[480sparky]

I've not looked at this, but it may be worth a try: DOF simulator - Camera depth of field calculator with visual background blur and bokeh simulation.

DOF, bokeh and background blur have nothing to do with rendering facial features proportionally correct.

 

[Dave Maciak]

Your example is somewhat misleading as Barrel and Pincusion are both part of the same type of distortion. On the left, Barrel Dstortion causes straight lines to curve outward, or inward (Pin Cushion), and is affected by lens design and FL. 50mm lens are relatively easy to design and are virtually free of this type of distortion. Shorter FLs have more barrel distortion while longer FLs have pin cushion.

Good portrait photographers use this knowledge to enhance or subtract from facial features. IE Thinning chubby cheeks, adding fill to hollow cheeks,.

The other kind of distortion is Perspective Distortion. The effect that objects closer appear larger while something farther away appears smaller. It is as others have mentioned dependent on POV. If you look at a face from X distance and it appears natural, then so should a photo. However you need to remember to actually look at the whole face (nose, eyes, ears, hair) because there's a tendency to only concentrate on one feature.

So to answer your question there is no one size fits all answer as it is dependent on lens design, desired FOV, FL, the acceptable amount of distortion, space available to setup, and POV. That might be anywhere from minimum focal distance to ????. The only way to answer that question is to set your camera on a fixed tripod and shoot different FLs test shots, move the tripod and repeat.

Best response yet from the poster. Years ago working in a portrait studio with a huge camera using 5x7 sheet film, using 4 strobes (main, fill, hair background) all of which were on caster wheels and extremely mobile, bar doors and all. The boss was a Master Photographer with many years of experience . We got great results. The OP is right. Control light and distance.
Many "on line experts" say use (whatever) this focal length.. Must be selling lenses.