Focal length vs. field of view?

[MAubrey]

No, portraits are usually taken at about the same distances, regardless of format. If you are using lenses appropriate for portraiture for each format.
You want to be close enough to the subject to direct them and relate to them. Except for some environmental distant portraits.

I don't know who you're talking to, but you're not talking to me.

[Bob Salomon]

“So often a LF lens has a way larger circle than it's needed to cover the format, this allows rise-shift movements for perspective control.”

No!!!

Perspective is controlled by the angle of the camera to the subject.

Direct displacements do not control perspective.

[consummate_fritterer]

I'm only repeating what others have written but maybe this is a little easier to understand.

Foreshortening (many call this perspective distortion) is affected by subject to camera/lens distance. Short (wide) lenses include more of the periphery whereas long lenses magnify the center of the subject at the film plane.

Consider taking a close head shot of a person. On 135 format the person's face size on film will be greatly reduced from real life size. But on 11x14 film their face will be approximately life size, or 1:1 reproduction.

To achieve 1:1 reproduction of a subject on film requires approximately double the focal length of the lens. When a lens is extended to double its focal length, its effective focal length is doubled.

So, on 135 format a 135mm lens is a good focal length for a close face portrait and because the image on film is tiny and the lens is only focus outward a little bit, the focal length only increases a little bit, say it's effectively 150mm (approx).

However, on 11x14, with the lens extended to double its focal length to fill the film with the subject's face, its effective focal length is doubled. So, for this format a 'normal' lens (450mm) or a very 'slightly' longer lens is a better option if the goal is to match the perspective of the same subject shot on 135 format. Of course, the depth of field is vastly different due to the great difference in lens focal lengths but that's a separate issue.

The effect increases as film size increases. The difference in effect between 135 and medium format is relatively negligible. The difference in effect between 6x6cm and 4x5 inch is more noticeable but not extreme, as it is between 135 and 11x14.

[Bob Salomon]

I'm only repeating what others have written but maybe this is a little easier to understand.

Foreshortening (many call this perspective distortion) is affected by subject to camera/lens distance. Short (wide) lenses include more of the periphery whereas long lenses magnify the center of the subject at the film plane.

Consider taking a close head shot of a person. On 135 format the person's face size on film will be greatly reduced from real life size. But on 11x14 film their face will be approximately life size, or 1:1 reproduction.

To achieve 1:1 reproduction of a subject on film requires approximately double the focal length of the lens. When a lens is extended to double its focal length, its effective focal length is doubled.

So, on 135 format a 135mm lens is a good focal length for a close face portrait and because the image on film is tiny and the lens is only focus outward a little bit, the focal length only increases a little bit, say it's effectively 150mm (approx).

However, on 11x14, with the lens extended to double its focal length to fill the film with the subject's face, its effective focal length is doubled. So, for this format a 'normal' lens (450mm) or a very 'slightly' longer lens is a better option if the goal is to match the perspective of the same subject shot on 135 format. Of course, the depth of field is vastly different due to the great difference in lens focal lengths but that's a separate issue.

The effect increases as film size increases. The difference in effect between 135 and medium format is relatively negligible. The difference in effect between 6x6cm and 4x5 inch is more noticeable but not extreme, as it is between 135 and 11x14.

Let’s start all over, and wipe your mind clear of what you read!

Foreshortening means that things closer to the lens reproduce larger then things further from the lens.

The wider, or shorter, the lens the greater the effect is.

Long lenses minimize foreshortening, wide lenses maximize it.

That is why portraits are usually done with lenses longer then normal focal lengths.

[consummate_fritterer]

Yes, we do indeed need to cull through misinformation.

[Pere Casals]

“So often a LF lens has a way larger circle than it's needed to cover the format, this allows rise-shift movements for perspective control.”

No!!!

Perspective is controlled by the angle of the camera to the subject.

Direct displacements do not control perspective.

Bob, lenses that are suitable for architecture (the perspective control realm) sport a really large circle to perform step c in this procedure:


If a large circle is not necessary for perspective control then why architectural lenses have mastodontic circles ?

It is true that we can also shift the circle with a front tilt, but we also require a large circle.

[Dan Fromm]

Papi, converging verticals as are eliminated by leveling the camera and using front rise or rear fall to adjust the framing have nothing to do with what most of us think of as perspective.

[Pere Casals]

Papi, converging verticals as are eliminated by leveling the camera and using front rise or rear fall to adjust the framing have nothing to do with what most of us think of as perspective.

Dan I was referring this kind of perspective control:

https://en.wikipedia.org/wiki/Perspective_control

I'd say this used widely in photography, even in small formats, as in Nikon PC-E lenses, sporting a rise, PC stands for perspective control.



What do you understand for "Perspective Control" ?

[Bob Salomon]

Bob, lenses that are suitable for architecture (the perspective control realm) sport a really large circle to perform step c in this procedure:


If a large circle is not necessary for perspective control then why architectural lenses have mastodontic circles ?

View cameras use either direct movements, rise/fall/shift, or indirect movements, tilt/swing.

For things that will show keystoning - buildings for instance.

First level the camera. Then with direct movements, raise the front and lower the back until the building is framed properly.

For indirect movements, level the camera, tilt the front till the building is positioned as desired then tilt the back the same degree.

Not enough direct movement available, then combine them with indirect movements.

Linhof, for one, monorail cameras have exceptionally large direct movements and many models, from the B up, accept accessory 3.5” extensions to add front or rear rise. So Linhof used direct movements primarily as they are faster and easier then indirect movements.

Other systems with limited direct movements rely primarily on indirect movements.

To take complete advantage of direct movements lenses with large image circles have to be used.

The end result is the same with either type of movements.

One point of warning. If the building is reproduced with perfectly parallel sides it will appear to some viewers that it is leaning backwards.

It is true that we can also shift the circle with a front tilt, but we also require a large circle.

[cowanw]

Are mastodontic circles the opposite of crop circles?