Portrait lense

[Donald]

Why is a 50mm lens so popular on FF cameras?

Because it equates to the view that the naked human eye has of the world.

[rpcrowe]

How much distortion can you expect to get with a 50mm lens on a FF camera?
Why is a 50mm lens so popular on FF cameras?

How far is 35mm on a CF camera removed from 50mm on a FF camera?

I expect that you are referring to distortion in portraits. The distortion is not determined by the focal length you are shooting with. It is determined by the lens to subject distance.

If you were shooting a portrait using a 200mm lens and then switched to a wide angle lens from the exact same distance, there would be absolutely no difference in distortion or prospective. Enlarging the image from the wide angle lens (as long as we are not talking about a fisheye lens) so that the subject's head is the same size as in the image with the telephoto lens, you will see exactly the same amount of distortion and the same perspective. Of course resulting from the large blow-up image quality would be deteriorated which is why people don't just use a wide angle lens for all shots and then crop the image to what they want.

The same thing applies to 50mm lenses vs. 100+ mm lenses. You would normally shoot from a closer distance with the 50mm than the 100+ mm lens.

However when we are talking about a cause and effect relationship, using a wide angle lens for head and shoulders portraiture will usually result in distortion because you will normally shoot from a closer lens to subject distance in order to fill the frame.

If you are shooting with a Nikon crop camera (1.5x crop) a 35mm lens on that camera will cover almost exactly the same field as a 50mm lens on a full frame camera. 35mm x 1.5x = 52.5mm, 2.5mm difference is hardly worth mentioning.

You can simulate the different focal lengths ysing this focal length simulator...
http://imaging.nikon.com/lineup/lens/simulator/

As far as why 50mm lenses are so popular... One reason is that you can get a very decent Canon or Nikon 50mm lens (usually about f/1.8) very inexpensively. Although the Canon 50mm f/1.8 lens is not the best lens in the world, it is head and shoulders above most kit lenses in both speed and image quality.

[William W]

The “distortions” which are being discussed in this thread are because of the CAMERA VIEWPOINT which was chosen and NOT the LENS which was chosen.

WW

PS Didn't see Richard's post before I posted mine.

[xpatUSA]

How much distortion can you expect to get with a 50mm lens on a FF camera?

None - with a Sigma EX DG 50mm f/2.8 Macro

Why is a 50mm lens so popular on FF cameras?

Because the literature says it matches our human perspective view. Hopefully, nobody will play the 'peripheral vision' card

How far is 35mm on a CF camera removed from 50mm on a FF camera?

About 25 degrees AOV.

[William W]

None - with a Sigma EX DG 50mm f/2.8 Macro . . .

The EF 50 F/2.5 is pretty good too.

[Texas Dave]

For what it's worth here are a few examples of the difference between a 50mm and a 200mm.

http://perkesphotography.blogspot.co...-vs-200mm.html

I was looking for examples of pure facial portraits. You have to see the difference between a 50mm and the 120-180mm range to understand the distortion some of these guys are talking about. It seems trivial until you see examples. Anyway, hope this helps.

[William W]

. . . You have to see the difference between a 50mm and the 120-180mm range to understand the distortion some of these guys are talking about. It seems trivial until you see examples. Anyway, hope this helps.

Again, the "distortion" is due to the Camera Viewpoint, not the Lens's Focal length.

WW

[Manfred M]

"Lens"

In fact there is no such thing as a "portrait" lens, any more than a wildlife lens or sports lens, the 85mm has just become associated with portraits because it allowed a head/shoulders shot from a decent distance.

ANY lens can be used for portraits from Fisheye to telephoto.

While this is technically correct, the ability to use a lens for a particular purpose does not mean it has not been specifically designed with a particular use or target audience in mind. You can use a pinhole camera to do a portrait as well as a 2000mm cat telescope that you attach a camera to. Neither of these tend to fall into the mainstream, and neither is using a a fisheye lens.

As a recently retired design engineer, I can virtually guarantee that certain specific lenses designed by Canon, Nikon and others we specifically targeted at portrait shooters. Before a designer begins to work he or she gets a list of requirements from the client. The more specific the requirements, the easier it is for the designer to create an end product that meets the target users needs.

I would say that both the f/2.8 24-70mm and f/2.8 70-200mm lenses by Canon and Nikon were specifically designed for portrait photographers. The 24-70mm lens is aimed at wider shots; full bodies, groups, etc whereas the 70-200mm specifically hits the range where most people would tend to shoot portraits. I can't think of any of the pros I know personally that don't use both of these lenses for most of their portraiture work. Not only do the focal lengths work, but they have that beautiful creamy bokeh that portrait shooters look for in their non-studio work.

So yes, there are lenses that have been designed with the portrait photographer in mind, and yes, they can be used for other types of photography. Likewise other lenses can be used for portaiture, but they may not always perform as well, even though they run through typical focal lengths used for portraiture. I'm also pretty sure that the Nikkor f/2 105 DC and the f/2 135 DC were also designed for portraiture, as both deliver great bokeh sought after in portraits.

Let's face it; the biggest market single for high end lenses for Canon and Nikon are the photographers that shoot people for a living; i.e. portraits. I can't think of a single reason why the designers of these lenses would not have worked on the requirements these photographers need.

[AB26]

Because it equates to the view that the naked human eye has of the world.

In other words Donald, MINIMAL "distortion".

Getting back to my shot of the little girl, shot with a 35mm lens on a CF camera: How much is it distorted?

[Manfred M]

In other words Donald, MINIMAL "distortion".

Getting back to my shot of the little girl, shot with a 35mm lens on a CF camera: How much is it distorted?

No Andre, your conclusion is not correct. The definition of a "normal" lens is based on the field of view, and has nothing whatsoever to do with distortion. As others have pointed out, the distance from the lens (magnification) to the subject is what drives the distortion.

In your picture, the hand is most definitely distorted, as it is quite close to the camera. I would suggest that the forehead also looks like it might be distorted as it is closer to the camera than other parts of the face. The ears look like they might be too small as well.

Being that close to the face of your subject certainly results in some degree of distortion in your shot.

[tao2]

Why is a 50mm lens so popular on FF cameras?

Hi Andre,

It's more mundane than technical or practical. Think ah've mentioned it before on these pages. Mr. Barnack had several 50mm lenses lying around his workshop (from his experiments with moving pictures - which was where his heart really lay). He really wanted a 42/43mm lens which was the more correct fit for 36x24mm film (film diagonal being @ 43mm).

Old Mr. Leitz was a real tightwad (and also pretty skint at the time) so told him tae use a converted 50mm. Everyone who came after thought that if a 50mm was good enough for Leitz, it was good enough for them. So the legend was born...

PS Agree with Jeremy, any lens can be a portrait lens...e.g.

The distortion ye see in a photo shot wide angle (for example) is caused by the close viewpoint and is, in fact, correct perspective as yer eye would see it from the same viewpoint. The theoretically correct viewing distance for a contact print/neg. is the focal length of the lens. When ye print and enlarge ye should then view the print from the focal length x the amount of enlargement.

In the days of film, take a photo with a 24mm lens. It would normally be enlarged 5x, so a print should be viewed from 24mm x 5 = 120mm or about 4". In reality it would be viewed from about 10-12 inches thus the perspective looks wrong.

Viewing the print from the correct distance would show correct perspective (more or less) as, on top of all the above, yer brain normally rejects "wrong" perspective.

[William W]

Only referring to the shot of the “Little Girl”.

The Subject’s Left Hand is rendered bigger than the Subject’s Right Hand. This effect is termed FORESHORTENING (sometimes also “EXTENSION”).

What is more difficult to see at first glance is the discrepancy between the size of the hands (plural) and the size of the Child’s face. But even without seeing the child in person it is a very safe bet of one mars bar that the hands are rendered “too big” with respect to the size of the Child’s face.

The FORESHORTENING effect is because the Camera so close to the Subject that the various distances from the camera to various parts of the subject render those different portions of the Subject which are closer to the camera BIGGER and those portions of the Subject which are farther away from the Camera are rendered relatively SMALLER.

It is possible that there is a small amount of KEYSTONING, which is rendering the Child’s Forehead broader (wider) than it actually is with respect to the chin and neck. The effect has to do with the camera ELEVATION.

***

FORESHORTENING and other similar effects (for example KEYSTONING) are the result of the CAMERA VIEWPOINT.
The CAMERA VIEWPOINT has TWO FACTORS:

a) the DISTANCE from CAMERA to the SUBJECT
- AND –
b) the ELEVATION of the CAMERA (Height from ground level)

***

These effects, (like FORESHORTENING) are often loosely termed “Perspective Distortion”, and I think that causes confusions with LENS DISTORTIONS (for example BARREL DISTORTION) and thereby these effects (such as FORESHORTENING) are often attributed to the LENS which is used – and doing so is incorrect.

WW

[xpatUSA]

It is possible that there is a small amount of KEYSTONING, which is rendering the Child’s Forehead broader (wider) than it actually is with respect to the chin and neck. The effect has to do with the camera ELEVATION.

***

FORESHORTENING and other similar effects (for example KEYSTONING) are the result of the CAMERA VIEWPOINT.

The CAMERA VIEWPOINT has TWO FACTORS:

a) the DISTANCE from CAMERA to the SUBJECT
- AND –
b) the ELEVATION of the CAMERA (Height from ground level)

WW

Would like to suggest that elevation defined as height from ground level might not apply to all shots.

An extreme example being shots of the space shuttle from the international space station. I'm wondering if the second factor might also be expressed as an angle or vector from the lens center-line?

Not that it would help much with this "shot" by Hogarth:



From https://simple.wikipedia.org/wiki/Pe...28graphical%29

Probably because he used two ~17mm focal length corneae ;-)

[William W]

Would like to suggest that elevation defined as height from ground level might not apply to all shots. . .etc.

Good point.

I understand.

The height from Ground Level is the "Elevation of the Camera": that is the term (and the measurement) used as one of the factors to describe the CAMERA VIEWPOINT.

I understand the space station example is an extreme example - BUT - the conundrum begins to exist in ‘simple’ Photography when the CAMERA’s ANGLE, (the long axis of the lens) relative to ground level begins to approach 45°; that's the point where this traditional definition of the Camera Viewpoint can be lacking.

*

For example, if we are taking a Portrait of a Child standing on the ground and we are (a tad over) 2 meters tall and we hold the camera at eye level. We are 3 meters from the Child - that's easy to describe the Camera Viewpoint:
Subject Distance (SD) = 3000mm; Camera Elevation 2000mm.

But as we walk closer to the child until the camera is pointing straight downward and we are viewing (a perfect plan view) of the top of the child's head. In this situation, using the traditional definition of Camera Viewpoint we are at 0 (zero) meters SD. That's the conundrum.

Obviously the camera in fact “a distance from the child” and (as suggested) using the angle of the camera's lens axis (now at 90 degrees) would be helpful.

What term is used in this situation (and I have only noted this in Cinematography) is "Perfect Overhead Shot".

Obviously all the effects of PERSPECTIVE still apply to this "Perfect Overhead" Portrait of the Child: that would be exactly as if the Child were laying straight on the ground - and the camera was at Ground Level. - and this fact kind of removes the conundrum, because we can now think of and describe the Camera Viewpoint in the Vertical Plane rather than the Horizontal Plane.


*

As another example, when setting the TV cameras at a Sports Coverage – (let’s say Cricket), the DP (Director of Photography) would describe the Cameras’ Viewpoints in: Distance (from the wicket); and Height (above ground level).

There is no practical purpose in having any camera’s axis downward more than or even anywhere close to 45° - but if there were, there again the traditional description of Camera Viewpoint does have a flaw. Noting also that the HIGHER cameras are most often the more DISTANT cameras.

*

I expect that using an angle as a descriptive, did not and still does not now gain much residency or usage, because it would only be rare and/or unusual occasions that it would be required in mainstream Still Photography and Cine work.

In these rare cases it could be (and is) accommodated, as and when required.

Taking the aforementioned Child Portrait as an example as how we might accommodate an unusually shooting scenario where the camera has an extreme downward angle: as we get really close to the Child then a more useful description of the CAMERA VIEWPOINT could be:
“Camera Viewpoint - SD= 1000mm; Elevation 500mm above Child’s Head”

But, it continues today that on: Lighting Sets; Sound Stages; Recording Studios; Outside Broadcasts & Telecasts and Stills Studios . . . Tape Measures are used much more often than Protractors - most probably because it is just simply easier.

WW

[xpatUSA]

Good point.

I understand.

The height from Ground Level is the "Elevation of the Camera": that is the term (and the measurement) used as one of the factors to describe the CAMERA VIEWPOINT.

. . . it continues today that on: Lighting Sets; Sound Stages; Recording Studios; Outside Broadcasts & Telecasts and Stills Studios . . . Tape Measures are used much more often than Protractors - most probably because it is just simply easier.

WW

Yes, easier and it works. Much like carpentry, where we could express roof pitch as a angle but rarely do so because run and rise tables on one's framing square are so much easier.

[William W]

Yes!

"Run and Rise" for roof pitch is a really good analogy.

*

BTW - the only consistent and necessary use of "Camera Angle" for Photography (that I have noted), is for Astrophotography, where the (resultant) Camera Angle is one datum required, to exact the (maximum) Shutter Speed necessary, to avoid Unwanted Blur, due to Movement.

WW

[AB26]

Only referring to the shot of the “Little Girl”.

The Subject’s Left Hand is rendered bigger than the Subject’s Right Hand. This effect is termed FORESHORTENING (sometimes also “EXTENSION”).

The FORESHORTENING effect is because the Camera so close to the Subject that the various distances from the camera to various parts of the subject render those different portions of the Subject which are closer to the camera BIGGER and those portions of the Subject which are farther away from the Camera are rendered relatively SMALLER.

WW

Is FORESHORTENING not PERSPECTIVE DISTORTION rendering the objects closer to the camera smaller and the objects further away from the camera to look bigger than it would appear in linear perspective?

[xpatUSA]

Is FORESHORTENING not PERSPECTIVE DISTORTION rendering the objects closer to the camera smaller . .

No, it renders them shorter.

https://en.wikipedia.org/wiki/Perspe...Foreshortening

and the objects further away from the camera to look bigger than it would appear in linear perspective?

I guess we would call that AFTLENGTHENING ;-)

(can we stop capitalizing words now? I doubt that Bill is amused . . .)