Portraits and lens distortion: connecting the dots

WedrerWaas · Feb 12, 2017

Hello,

Right from the start, all tutorials, books and videos that teach portrait photography warn you not to go below 70 or 85mm when shooting portraits, to avoid unflattering distortion on the subject.

These same sources introduced all the “crop factor” on a separate chapter.

Basically, if you’re using a 50mm on an APS-C camera, you will get the equivalent zoom of a 75mm lens installed on a Full Frame.

Then the natural first question came to me:

Q1: Is it OK then to shoot a portrait with a 50mm installed on an APS-C, since it’s the equivalent of a 75mm on a Full Frame, which gives little distortion?

Q2: Does the same lens create the same amount of distortion on APS-C as in a Full Frame?

Later, I started learning how to use Lightroom and I discovered the lens distortion correction feature.
And a new question popped up in my mind:

Q3: Does this feature allow me to use a 50mm or below lens in my portraits work?

Q4: Should I always apply this correction from 50mm to lower FL?

Later, I learned a “safety rule” in portrait photography, that can be formulated in two different ways:

1/ To decrease distortion, the wider your lens, the more “body parts” you need to include in your shot (i.e. 85mm for a head only picture, 50mm for a portrait from the waist to the head).
2/ To decrease distortion, the wider your lens, the further from the edges you place the subject, especially his/her face. (because the distortion is stronger around the edges).

I try to follow this rule as much as I can, but I still hope I can get a final answer to the 4 questions above.

One last question, related to the same topic:

Q5: People love taking selfies with their phone.
The focal length is usually below 35mm, and the zoom on the face is quite important.
How come they are not bothered by the distortion?
Do phones apply automatically a software correction?

Thank you so much for helping me better understand this very specific topic!

Regards.

@Wedrer_Waas

gordonpritchard · Feb 12, 2017

The distortion is not caused by the lens. It is caused by how close you are to the subject when you fill the frame with a face. The closer you are in order to fill the frame with only the face the more distortion you'll get. The 50mm/75mm guide creates a similar distortion to what the eye sees at the typical distances people interact at.

KCook · Feb 12, 2017

WedrerWaas said:
Hello,

Right from the start, all tutorials, books and videos that teach portrait photography warn you not to go below 70 or 85mm when shooting portraits, to avoid unflattering distortion on the subject.

These same sources introduced all the “crop factor” on a separate chapter.

Basically, if you’re using a 50mm on an APS-C camera, you will get the equivalent zoom of a 75mm lens installed on a Full Frame.

Then the natural first question came to me:

Q1: Is it OK then to shoot a portrait with a 50mm installed on an APS-C, since it’s the equivalent of a 75mm on a Full Frame, which gives little distortion?

Yes, so long as you don't get very close to the subject. As the other post said, this distortion depends on the distance to the subject, not really the lens.

WedrerWaas said:
Q2: Does the same lens create the same amount of distortion on APS-C as in a Full Frame?

At the same distance to the subject, yes.

WedrerWaas said:
Later, I started learning how to use Lightroom and I discovered the lens distortion correction feature.
And a new question popped up in my mind:

Q3: Does this feature allow me to use a 50mm or below lens in my portraits work?

Not really. Different kind of distortion.

WedrerWaas said:
Q4: Should I always apply this correction from 50mm to lower FL?

Sure, regardless of focal length.

WedrerWaas said:
Later, I learned a “safety rule” in portrait photography, that can be formulated in two different ways:

1/ To decrease distortion, the wider your lens, the more “body parts” you need to include in your shot (i.e. 85mm for a head only picture, 50mm for a portrait from the waist to the head).

True, but only when it results in you backing away from the subject to get those extra parts in the frame.

WedrerWaas said:
2/ To decrease distortion, the wider your lens, the further from the edges you place the subject, especially his/her face. (because the distortion is stronger around the edges).

True.

WedrerWaas said:
I try to follow this rule as much as I can, but I still hope I can get a final answer to the 4 questions above.

One last question, related to the same topic:

Q5: People love taking selfies with their phone.
The focal length is usually below 35mm, and the zoom on the face is quite important.
How come they are not bothered by the distortion?

I have no clue, I hate selfies.

WedrerWaas said:
Do phones apply automatically a software correction?

Not that I am aware of.
Links for more info on photographing people and lens usage -

How to Use a Wide-Angle Lens for People Photography

HOW TO FIND THE PERFECT PORTRAIT LENS TO AVOID DISTORTION

Does Focal Length Distort Subjects?

Kelly Cook

Mark S Abeln · Feb 12, 2017

A much easier rule to remember is to stand at least 10-15 feet from your subject, no matter your lens or sensor crop factor. You use a wider lens for whole body and a longer lens for headshots.

Tim Reidy Productions · Feb 12, 2017

WedrerWaas said:
Hello,

Q1: Is it OK then to shoot a portrait with a 50mm installed on an APS-C, since it’s the equivalent of a 75mm on a Full Frame, which gives little distortion?

yes on a pentax they have a 55mm for portraits.

WedrerWaas said:
Q2: Does the same lens create the same amount of distortion on APS-C as in a Full Frame?

Later, I started learning how to use Lightroom and I discovered the lens distortion correction feature.
And a new question popped up in my mind:

no it depends on the body placed upon it for the true distortion mark.

WedrerWaas said:
Q3: Does this feature allow me to use a 50mm or below lens in my portraits work?

you can use anything for portraits but the 85mm at ff is most ideal, but you should experience on your subject to see what focal length you like with your particular subject.

WedrerWaas said:
Q4: Should I always apply this correction from 50mm to lower FL?

I dunno

WedrerWaas said:
Later, I learned a “safety rule” in portrait photography, that can be formulated in two different ways:

1/ To decrease distortion, the wider your lens, the more “body parts” you need to include in your shot (i.e. 85mm for a head only picture, 50mm for a portrait from the waist to the head).
2/ To decrease distortion, the wider your lens, the further from the edges you place the subject, especially his/her face. (because the distortion is stronger around the edges).

I try to follow this rule as much as I can, but I still hope I can get a final answer to the 4 questions above.

One last question, related to the same topic:

Q5: People love taking selfies with their phone.
The focal length is usually below 35mm, and the zoom on the face is quite important.
How come they are not bothered by the distortion?

you just go with what you got, it is hard to go with a telephoto on a self portrait hand held

LynniePad · Feb 12, 2017

WedrerWaas said:
Hello,

Right from the start, all tutorials, books and videos that teach portrait photography warn you not to go below 70 or 85mm when shooting portraits, to avoid unflattering distortion on the subject.

These same sources introduced all the “crop factor” on a separate chapter.

Basically, if you’re using a 50mm on an APS-C camera, you will get the equivalent zoom of a 75mm lens installed on a Full Frame.

Then the natural first question came to me:

Q1: Is it OK then to shoot a portrait with a 50mm installed on an APS-C, since it’s the equivalent of a 75mm on a Full Frame, which gives little distortion?

Q2: Does the same lens create the same amount of distortion on APS-C as in a Full Frame?

Later, I started learning how to use Lightroom and I discovered the lens distortion correction feature.
And a new question popped up in my mind:

Q3: Does this feature allow me to use a 50mm or below lens in my portraits work?

Q4: Should I always apply this correction from 50mm to lower FL?

Later, I learned a “safety rule” in portrait photography, that can be formulated in two different ways:

1/ To decrease distortion, the wider your lens, the more “body parts” you need to include in your shot (i.e. 85mm for a head only picture, 50mm for a portrait from the waist to the head).
2/ To decrease distortion, the wider your lens, the further from the edges you place the subject, especially his/her face. (because the distortion is stronger around the edges).

I try to follow this rule as much as I can, but I still hope I can get a final answer to the 4 questions above.

One last question, related to the same topic:

Q5: People love taking selfies with their phone.
The focal length is usually below 35mm, and the zoom on the face is quite important.
How come they are not bothered by the distortion?
Do phones apply automatically a software correction?

Thank you so much for helping me better understand this very specific topic!

It's not distortion, just a subject-distance effect,and you are getting confused with the minor non-rectilinear distortion inherent in some lenses. The latter effect can be corrected, but the subject-distance cannot.

I define distortion as being an unexpected effect that can't be explained by simple geometry. For example, if you are very close to your portrait subject, the nose will look enormous. Similarly, figures at the edges of shots taken with wide-angle lenses will be very "stretched" in a very unflattering manner. These cases are not distortions, just perspective effects.

WedrerWaas · Feb 12, 2017

Thank you @KCook for the answers and the research web links!

LynniePad · Feb 12, 2017

WedrerWaas said:
Thank you @KCook for the answers and the research web links!

Yes, but only one of those links is written with any understanding.

Does Focal Length Distort Subjects?

photographylife.com

The others are rubbish.

John Deerfield · Feb 12, 2017

To sum it up: the only thing that determines perspective is distance. Period. The lens has nothing to do with it. The camera has nothing to do with it. Distance & distance alone determines perspective. Now perspective is the spatial relationship between objects in an image. Which, simply put means that subjects closer to the lens appear larger than subjects further from the lens (distance!).

Many times the effect of a telephoto lens will be described as "compressing" the scene. It isn't the lens that does this, it is the fact that with a longer lens you are shooting from a longer distance. Conversely, many will say that a wide lens "distorts" the scene. Again, not true. It is the distance. Shooting with a wider lens means you encompass more of what is in the foreground. The foreground is closer to the lens, thus larger. However, if you stood at the same distance and shot a the same scene with both a wide and and then a longer lens, the perspective would be identical (because the distance is the same).

How might this apply to portrait photography?

- ever seen a picture take of a basketball player from the ground up? This makes the player look "taller". Why? What is closest to the lens? The legs will appear larger whilst the head will appear smaller.

- what if your subject has a long nose and they are self-conscious about this feature? If you shot from a relatively close position, the nose will be larger (what is closest to the lens?). As your shooting distance increases (thus a longer lens for the same framing), the relative "size" of the nose diminishes in "spatial relationship" to the rest of the face.

- but what if you are shooting a face with strong features? High cheekbones or chiseled jawline? Now you want to shoot closer (compared to a telephoto) to emphasize those features.

- What if I am shooting someone with a spare tire? Have the subject lean forward. This places the head closer to the camera. What happens to things closer to the lens? In turn, this means the spare tire is further from the lens. What happens to things further from the lens?

-full length fashion shots tend to be shot at the waist level. Why? There is an equal distance between feet and head!

- Head shots tend to be shot at eye level or slightly above. Why?

The list goes on, but the rule does't change because it's the physics of how optics work: distance and distance alone determines perspective.

Cherylynne1 · Feb 12, 2017

WedrerWaas said:
Hello,

Right from the start, all tutorials, books and videos that teach portrait photography warn you not to go below 70 or 85mm when shooting portraits, to avoid unflattering distortion on the subject.

These same sources introduced all the “crop factor” on a separate chapter.

Basically, if you’re using a 50mm on an APS-C camera, you will get the equivalent zoom of a 75mm lens installed on a Full Frame.

Then the natural first question came to me:

Q1: Is it OK then to shoot a portrait with a 50mm installed on an APS-C, since it’s the equivalent of a 75mm on a Full Frame, which gives little distortion?

Q2: Does the same lens create the same amount of distortion on APS-C as in a Full Frame?

Later, I started learning how to use Lightroom and I discovered the lens distortion correction feature.
And a new question popped up in my mind:

Q3: Does this feature allow me to use a 50mm or below lens in my portraits work?

Q4: Should I always apply this correction from 50mm to lower FL?

Later, I learned a “safety rule” in portrait photography, that can be formulated in two different ways:

1/ To decrease distortion, the wider your lens, the more “body parts” you need to include in your shot (i.e. 85mm for a head only picture, 50mm for a portrait from the waist to the head).
2/ To decrease distortion, the wider your lens, the further from the edges you place the subject, especially his/her face. (because the distortion is stronger around the edges).

I try to follow this rule as much as I can, but I still hope I can get a final answer to the 4 questions above.

One last question, related to the same topic:

Q5: People love taking selfies with their phone.
The focal length is usually below 35mm, and the zoom on the face is quite important.
How come they are not bothered by the distortion?
Do phones apply automatically a software correction?

Thank you so much for helping me better understand this very specific topic!

Regards.

@Wedrer_Waas

As others have mentioned, you're mixing up distortion of the lens with distortion from the distance between you and the subject.

Some lenses, particularly cheap lenses, need to make a lot of compromises in production. One thing that sometimes happens is that the edges or corners will curve and need to be corrected by software, like in Lightroom. Unless you're testing a lens for a preofessional review, I don't see much point in not applying the software to every photo taken with that lens so you don't have to worry about it. I'm pretty sure Lightroom applies it by default for every lens they have in their database. However, that has nothing really to do with portraits.

It's not really so much that the focal length will magically make a face look better, it's the fact that longer focal lengths force you to stand further back from the person. The closer you are, the more it will appear that objects closer to the camera are larger. Noses are a big problem with this, and sometimes stomachs as well. You have the idea down, it just seems you're a little uncertain on the reasoning.

As for selfies, this is a big issue. Have you ever watched a teenage girl take a selfie? They take dozens before choosing the one to post. This is because even the tiniest movement of their head or hand make a massive difference in the appearance of the photo. Often they have their chin down, nose to the side, and the camera high and as far away as they can get it. This is in an attempt to make their eyes the closest thing to the camera, which makes their eyes look larger than normal. They don't avoid distortion, they've developed ways to utilize it. Don't get me wrong, I get annoyed by selfies as much as the next person, but it actually takes quite a bit of talent to take a flattering headshot with a wide angle lens and capture the landscape behind you to show where you are.

Bob · Feb 18, 2017

WedrerWaas said:
Hello,

Right from the start, all tutorials, books and videos that teach portrait photography warn you not to go below 70 or 85mm when shooting portraits, to avoid unflattering distortion on the subject.

These same sources introduced all the “crop factor” on a separate chapter.

Basically, if you’re using a 50mm on an APS-C camera, you will get the equivalent zoom of a 75mm lens installed on a Full Frame.

No, not equivalent ZOOM. Zoom implies a magnification; cropping does not. A 50mm gives the exact same magnification, regardless of what the sensor size it. You won't get any more detail from a lens by simply putting in on a smaller sensor.

WedrerWaas said:
Then the natural first question came to me:

Q1: Is it OK then to shoot a portrait with a 50mm installed on an APS-C, since it’s the equivalent of a 75mm on a Full Frame, which gives little distortion?

Perhaps this will help:

Examples

WedrerWaas said:
Q2: Does the same lens create the same amount of distortion on APS-C as in a Full Frame?

Later, I started learning how to use Lightroom and I discovered the lens distortion correction feature.
And a new question popped up in my mind:

Q3: Does this feature allow me to use a 50mm or below lens in my portraits work?

Q4: Should I always apply this correction from 50mm to lower FL?

Later, I learned a “safety rule” in portrait photography, that can be formulated in two different ways:

1/ To decrease distortion, the wider your lens, the more “body parts” you need to include in your shot (i.e. 85mm for a head only picture, 50mm for a portrait from the waist to the head).
2/ To decrease distortion, the wider your lens, the further from the edges you place the subject, especially his/her face. (because the distortion is stronger around the edges).

WedrerWaas said:
I try to follow this rule as much as I can, but I still hope I can get a final answer to the 4 questions above.

One last question, related to the same topic:

Q5: People love taking selfies with their phone.
The focal length is usually below 35mm, and the zoom on the face is quite important.
How come they are not bothered by the distortion?
Do phones apply automatically a software correction?

Thank you so much for helping me better understand this very specific topic!

Regards.

@Wedrer_Waas

Bobby49 · Feb 18, 2017

It used to be that a portrait photographer would shoot with a 70mm lens for a normal subject to avoid getting distortion in the appearance of the nose. Then if you were shooting an Italian with a Roman nose, you would shift over to an 80mm lens.

I had to shoot a Greek, and I had to go to a 110mm lens.

LynniePad · Feb 18, 2017

Bobby49 said:
It used to be that a portrait photographer would shoot with a 70mm lens for a normal subject to avoid getting distortion in the appearance of the nose. Then if you were shooting an Italian with a Roman nose, you would shift over to an 80mm lens.

I had to shoot a Greek, and I had to go to a 110mm lens.

Noses vary with age as well as geography; you can safely get closer when snapping children.

Stejo · Feb 20, 2017

Bob said:
WedrerWaas said:

These same sources introduced all the “crop factor” on a separate chapter.

Basically, if you’re using a 50mm on an APS-C camera, you will get the equivalent zoom of a 75mm lens installed on a Full Frame.

Click to expand...

No, not equivalent ZOOM. Zoom implies a magnification; cropping does not. A 50mm gives the exact same magnification, regardless of what the sensor size it.

Yes.

Bob said:
You won't get any more detail from a lens by simply putting in on a smaller sensor.

No.

This has to do with the resolving power of the lens matched against the resolution of the sensor. In many cases a smaller sensor will have 3 or 4 times more pixels packed in the same area compared to the bigger sensor. If the lens is sharp enough you will absolutely get more detail out of it.

LynniePad · Feb 20, 2017

Stejo said:
Bob said:

You won't get any more detail from a lens by simply putting in on a smaller sensor.

Click to expand...

No.

This has to do with the resolving power of the lens matched against the resolution of the sensor. In many cases a smaller sensor will have 3 or 4 times more pixels packed in the same area compared to the bigger sensor. If the lens is sharp enough you will absolutely get more detail out of it.

Care to give us some examples where the same lens gives better results on a smaller sensor? With the 3 or 4 times increase in pixel density, you would be rubbing up against limits imposed by the circle of confusion.

In more realistic scenarios, such as FF lenses on APS-C bodies, the smaller sensor is always at a disadvantage as regards resolution, although distortion and vignetting are improved.

In many cases (e.g. Nikon, Sony) the FF bodies have greater total pixel count and this increases their advantage.

Stejo · Feb 21, 2017

LynniePad said:
Stejo said:

Bob said:

You won't get any more detail from a lens by simply putting in on a smaller sensor.

Click to expand...

No.

This has to do with the resolving power of the lens matched against the resolution of the sensor. In many cases a smaller sensor will have 3 or 4 times more pixels packed in the same area compared to the bigger sensor. If the lens is sharp enough you will absolutely get more detail out of it.

Click to expand...

Care to give us some examples where the same lens gives better results on a smaller sensor? With the 3 or 4 times increase in pixel density, you would be rubbing up against limits imposed by the circle of confusion.

In more realistic scenarios, such as FF lenses on APS-C bodies, the smaller sensor is always at a disadvantage as regards resolution, although distortion and vignetting are improved.

In many cases (e.g. Nikon, Sony) the FF bodies have greater total pixel count and this increases their advantage.

Don't confuse yourself with circles; lpmm gives you all the info you need. The problem with satisfying your request is that you can't mount lenses designed for crop sensors on FF bodies because of flange distance and all. And using FF lenses on crop sensors doesn't net any advantage because they're not designed to be sharp enough for the pixel density of a crop sensor.

If we eventually get an 80MP FF sensor with lenses to match, you could demonstrate the difference, if that's what you need to understand it. You could maybe do it with some of the latest FF lenses too if you were to mount them on a 20 year old body, but since digital cameras are not that old, it'd be pretty hard to come up with something comparable.

Either way, this was a theoretical point. An infinitely sharp lens will produce more detailed crops on a sensor with higher pixel density. It would only be considered a magnification if the sensors had equal pixel density, but that's not the case with current technology.

tedolf · Feb 21, 2017

WedrerWaas said:
Hello,

Right from the start, all tutorials, books and videos that teach portrait photography warn you not to go below 70 or 85mm when shooting portraits, to avoid unflattering distortion on the subject.

These same sources introduced all the “crop factor” on a separate chapter.

Basically, if you’re using a 50mm on an APS-C camera, you will get the equivalent zoom of a 75mm lens installed on a Full Frame.

Then the natural first question came to me:

Q1: Is it OK then to shoot a portrait with a 50mm installed on an APS-C, since it’s the equivalent of a 75mm on a Full Frame, which gives little distortion?

Q2: Does the same lens create the same amount of distortion on APS-C as in a Full Frame?

Rectilinear lenses don't create distortion, at least not the kind you are talking about.....

distance does.

What you are talking about is perspective distortion and it is solely controlled by camera to subject distance. An 85mm equivalent lens merely allows you to fill the frame with the subject without you having to get so close (closer than about 10 feet) that you induce perspective distortion. You would get the same shot with a wide angle lens at 10 feet, but you would have to crop the Hell out of the result to get the same framing of the subject.

WedrerWaas said:
Later, I started learning how to use Lightroom and I discovered the lens distortion correction feature.

What you are seeing has nothing to do with lens distortion. Those features fix pin cushion and barrel distortion. Not perspective distortion from being too close.

WedrerWaas said:
And a new question popped up in my mind:

Q3: Does this feature allow me to use a 50mm or below lens in my portraits work?

No.

WedrerWaas said:
Q4: Should I always apply this correction from 50mm to lower FL?

no.

WedrerWaas said:
Later, I learned a “safety rule” in portrait photography, that can be formulated in two different ways:

1/ To decrease distortion, the wider your lens, the more “body parts” you need to include in your shot (i.e. 85mm for a head only picture, 50mm for a portrait from the waist to the head).

Yes, basically this is forcing you to back away.

WedrerWaas said:
2/ To decrease distortion, the wider your lens, the further from the edges you place the subject, especially his/her face. (because the distortion is stronger around the edges).

Yes, but that truly is barrel distortion.

WedrerWaas said:
I try to follow this rule as much as I can, but I still hope I can get a final answer to the 4 questions above.

One last question, related to the same topic:

Q5: People love taking selfies with their phone.
The focal length is usually below 35mm, and the zoom on the face is quite important.
How come they are not bothered by the distortion?

Because they are idiots.

WedrerWaas said:
Do phones apply automatically a software correction?

Yes, but not for perspective distortion which really can't be fixed in post processing.

WedrerWaas said:
Thank you so much for helping me better understand this very specific topic!

Regards.

@Wedrer_Waas

TEdolph

Aria Patel · Feb 21, 2017

Mark Scott Abeln said:
A much easier rule to remember is to stand at least 10-15 feet from your subject, no matter your lens or sensor crop factor. You use a wider lens for whole body and a longer lens for headshots.

tedolf · Feb 21, 2017

Aria Patel said:
Mark Scott Abeln said:

A much easier rule to remember is to stand at least 10-15 feet from your subject, no matter your lens or sensor crop factor. You use a wider lens for whole body and a longer lens for headshots.

--
http://therefractedlight.blogspot.com

Click to expand...

Pardon my ignorance but isn't 10-15 feet too much of a distance?

No.

Aria Patel said:
Especially if you're doing a headshot or if you're using say 35mm prime lens on a full frame camera?

No.

Tedolph

LynniePad · Feb 21, 2017

Stejo said:
LynniePad said:

Stejo said:

Bob said:

You won't get any more detail from a lens by simply putting in on a smaller sensor.

Click to expand...

No.

This has to do with the resolving power of the lens matched against the resolution of the sensor. In many cases a smaller sensor will have 3 or 4 times more pixels packed in the same area compared to the bigger sensor. If the lens is sharp enough you will absolutely get more detail out of it.

Click to expand...

Care to give us some examples where the same lens gives better results on a smaller sensor? With the 3 or 4 times increase in pixel density, you would be rubbing up against limits imposed by the circle of confusion.

In more realistic scenarios, such as FF lenses on APS-C bodies, the smaller sensor is always at a disadvantage as regards resolution, although distortion and vignetting are improved.

In many cases (e.g. Nikon, Sony) the FF bodies have greater total pixel count and this increases their advantage.

Click to expand...

Don't confuse yourself with circles; lpmm gives you all the info you need. The problem with satisfying your request is that you can't mount lenses designed for crop sensors on FF bodies because of flange distance and all. And using FF lenses on crop sensors doesn't net any advantage because they're not designed to be sharp enough for the pixel density of a crop sensor.

Swapping APS-C/FF is entirely possible with both Nikon and Sony.

I do it all the time with my Sony gear, and although the lenses that I use are plenty sharp enough to perform well on APS-C, the results on FF are better (even with same total pixel count).

Stejo said:
Either way, this was a theoretical point. An infinitely sharp lens will produce more detailed crops on a sensor with higher pixel density. It would only be considered a magnification if the sensors had equal pixel density, but that's not the case with current technology.

The CoC is what defeats the notion of an "infinitely sharp lens".

Magnification is not a useful concept in this discussion and, in general, most "cropology" discussions are unprofitable.

Portraits and lens distortion: connecting the dots

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