longer lenses perspective

[ifer]

hi,
i am just wondering.
are largeformat lenses focal lenght affect perspective like how the smaller formats lenses do?

if i use a 210mm lens, will my perspective be more 'compress' than a 150mm lens?

thanks for the answer

[Walter Calahan]

Yes, physics is physics.

A better test is to compare an even longer lens to your 150mm.

[Peter K]

The perspective has nothing to do with the lens, it's only a question of the point of view.

Without moving the camera you can take a picture with a 150mm lens and another with a 210mm. Than enlarge and crop the negative taken with the 150mm and you get the same perspective.

Peter K

[Brian Ellis]

I know what you're asking but lens focal length actually has no effect on perspective, the focal length of a lens only affects its angle of view. The only thing that affects perspective is your camera position. The "compressed" effect you mention with a long lens isn't caused by the length of the lens, it's caused by the apparent change in relative size of near and far objects as you move farther away from those objects (the near objects appear to get smaller faster than the more distant objects because you're moving proportionally farther away from the near objects so the near and far objects appear to be closer in size and thus closer together or "compressed"). The opposite is true with short focal length lenses, which is why the distance between near and far objects can appear to be exagerated with those kinds of lenses.

[Mark Sawyer]

It's kind of a messy subject, but yes, for a given view the 210mm will flatten/compress the viewer's perspective on space slightly. This is because at a given focusing distance and format, it will give a narrower angle of view, and it's the angle of view that determines the apparent compression of space.

A 210mm on a 5x7 will give about the same appearance of compression as a 150mm 0n a 4x5 or a 300mm on an 8x10, as all have about the same angle of view for their formats.

BTW, a 150mm on 4x5 at infinity is equivalent to a 50mm on a 35mm camera, and a 210mm is the equivalent of a 70mm, but if you focus closer with the 150mm, running the bellows out to 210mm, it gives an angle of view and compression effect equivalent to a 70mm on 35mm zoom lenses, where the lens focuses by moving internal elements and the rear element doesn't move...

[ifer]

wow! i am starting to get headache.
hehee!
thanks guys for the information.
so, the 'nearer background effect when using longer focal lenght lenses' do apply in large formats after all.
hehee!

[IanG]

so, the 'nearer background effect when using longer focal lenght lenses' do apply in large formats after all.


No, its not that simple, compression & perspective are not dependent on the focal length used, rather are governed only by the distance of the camera (more specifically the lens) from the subject.

So a 28mm lens on 35mm camera, 150mm on a 5x4, and 300mm on a 10x8 camera give roughly the same compression & perspective of a subject if the cameras are placed in the same position. Don't muddle angle of view with perspective.

Zooming or changing focal length while the camera remains in the same position only alters the angle of view/degree of image magnification on the negative, it does not alter perspective/compression.

In the case of a LF camera shooting close ups focussing can decrease the lens/camera to object distance altering the perspective.

Ian

[Ken Lee]

One thing follows another, and it's helpful if you consider them in the right order. Otherwise, you go around in circles and get a headache.

On a 35mm camera, a normal lens is considered roughly 50mm, since that is roughly the diagonal of the film frame. On 6x6, it is roughly 75mm. On 4x5, it is roughly 150.

Let's say you get those 3 cameras, place the appropriate "normal" lens on them. Place each camera 100 feet from a model. If you shoot a picture, (or simply look through the viewfinder or ground glass) each setup will give the same perspective and angle of view.

Now double the length of each lens, to 100, 150, and 300. Again, if you compare the images, they will have the same perspective and angle of view as one another.

One thing you will notice, however, is that longer lenses have less depth of field, no matter what size film you use. A 150mm lens, even though it's a normal lens for 4x5, will have to be stopped down 2 extra stops, in order to give the same DOF as a 75mm lens. (Each time you double the length, you have to double the f/stops).

Flattened perspective is gotten whenever the subject is far away. If you take a picture of someone's face from far away, using a 50mm lens on 35mm film, you will need to blow up the image rather large to see the face. Once you do, you will see that the face looks rather "flat". It will look equally flat if you shoot it with a 150mm lens on 35mm film, and don't blow it up at all. The 150 simply magnifies the same flat-looking face. It doesn't bring you closer.

The reason the face looks flat when you are far away, is that compared to the distance away from the subject, the distance from the person's nose, to their face, is very little. At 100 feet away, 2 inches is almost nothing. If you come in close, like 3 feet away, then that same 2 inches becomes... substantial. At very close range, the person's nose looks more like a... mountain.

It's all relative.

[Brian Ellis]

It's kind of a messy subject, but yes, for a given view the 210mm will flatten/compress the viewer's perspective on space slightly. This is because at a given focusing distance and format, it will give a narrower angle of view, and it's the angle of view that determines the apparent compression of space.

A 210mm on a 5x7 will give about the same appearance of compression as a 150mm 0n a 4x5 or a 300mm on an 8x10, as all have about the same angle of view for their formats. . . . . .

Once again from the top, lightly - Angle of view has nothing to do with perspective or "compression." The only thing that affects perspective is the position of the camera relative to the objects in the scene. A 210 mm lens doesn't inherently produce a more "compressed" look than a 75mm lens. It all depends on where the camera is placed relative to the objects in the scene.

[John O'Connell]

Brian is correct---angle of view is different than perspective compression.

Also---depth of field is not related to focal length.

[Helen Bach]

One more version:

Perspective in the image is determined solely by the position of the lens, specifically the entrance pupil.

Apparent perspective of the viewed image depends also on the relationship between the original angle of view and the angle of view of the print.

If you take a picture that has a horizontal angle of view of 60 degrees, then print it, then view the print such that the edges of the print image give an angle of view of 60 degrees, then the perspective you see will be the same as it was from the lens' position.

If you then take a picture with a 100 degree view, and look at the print with a 60 degree view, then the image will appear to have the perspective distortion commonly associated with wide angle lenses. If you bring the print closer, so that it has a 100 degree angle, the perspective will look natural.

The 'standard' lens for a 35 mm camera is a 50 mm. The 'standard' lens for a 35 mm projector is 100 mm (or thereabouts). That means that viewers mid-way between the projector and the screen will see a natural perspective when the 'standard' taking and projection lenses are used.

Best,
Helen

[Mark Sawyer]

I can, so to speak, see the different perspectives here...

Brian has a good point in saying:


Once again from the top, lightly - Angle of view has nothing to do with perspective or "compression." The only thing that affects perspective is the position of the camera relative to the objects in the scene. A 210 mm lens doesn't inherently produce a more "compressed" look than a 75mm lens. It all depends on where the camera is placed relative to the objects in the scene.

If object A is ten feet from the camera and object B is ten feet behind that, then object B is twice as far away as object A. But if you back up to where object A is a hundred feet away, then object B is only ten percent farther away than object A, regardless of the focal length.

Where I would differ regarding angle of view is that increasing it will alter the view itself, creating a feeling of more depth. Here is the view from a 75mm lens at a narrow angle of view on a 35mm, and the view from the same 75mm lens in the same place on an 8x10. For me, the 8x10 view feels like it has more space because, well, it captures more space, so I'm right. But Brian is also right in that the compression between objects is identical. It has to be; after all, it's the same lens in the same place, actually cropped from the same piece of film.

http://i55.photobucket.com/albums/g139/Owen21k/chicagostorehypergon337hi35.jpg

http://i55.photobucket.com/albums/g139/Owen21k/chicagostorehypergon337hi810.jpg

[Mark Sawyer]

(Continuing along...)

The thing about using a different focal length lens with a different angle of view is that, unless you're physically constrained, you end up putting the camera in a different place to capture the same subject. A few years ago I decided to try out half-a-dozen different focal lengths in the same place, but moving the camera around to keep the general view the same. (Leaving it in the same place would have just been an exercise in cropping out the middle; I wanted to see how they handled the same space and how I worked with that.)

So I found a spot that had a sense of space to it and blew some film. Here are two views on opposite ends of the spectrum, taken from different spots but capturing the same general area. The first is from a 480mm Apo-Ronar, (my longest 8x10 lens at the time), and the second from a 75mm Hypergon, (my shortest lens for the 8x10). For me, they give very different felings for the dpth of space:

http://i55.photobucket.com/albums/g139/Owen21k/480mmRonar500hi.jpg

http://i55.photobucket.com/albums/g139/Owen21k/75mmHypergon500hi.jpg

[ifer]

mark... god bless u.
i finally got what i want. from these images that you had posted. it is clearly visualized that the compressed perspective is affected by focal lenght.

thanks again.
and thanks to everyone who participate in this q&a session.
but keep the answers coming ya!

[Helen Bach]

...
BTW, a 150mm on 4x5 at infinity is equivalent to a 50mm on a 35mm camera, and a 210mm is the equivalent of a 70mm, but if you focus closer with the 150mm, running the bellows out to 210mm, it gives an angle of view and compression effect equivalent to a 70mm on 35mm zoom lenses, where the lens focuses by moving internal elements and the rear element doesn't move...

It sounds like the hypothetical 70 mm you are referring to is no longer a 70 mm when focused close, but a 50 mm. The equivalence between the 150 on 4x5 and the 50 on 35 mm stays the same as long as both lenses are focused at the same distance, surely.

There are motion picture lenses that deliberately adjust their focal length to maintain the same angle of view as they are focused - ie they have a shorter focal length when focused close than when focused far. If this didn't happen a focus pull would look like a mild zoom. There are also macro lenses for 35 mm that shorten as you focus closer. This enables them to reach 1:1 without excessive draw.

Best,
Helen

[Mark Sawyer]

mark... god bless u.
i finally got what i want. from these images that you had posted. it is clearly visualized that the compressed perspective is affected by focal length.

Thanks for the blessing! But is compression affected by focal length? Yes and no... If I'd photographed the woodland scene from the same place with both lenses and cropped the middle out of the negative made with the shorter lens, it would have looked the same as the view made with the longer lens, at least space-wise. But the shorter lens lets you move in closer while capuring the same general area, so THAT changes the perception of space...

As an extreme example think of the shorter lens letting you photograph from inside the space, where the longer lens lets you back up and look at the space from a distance. Different senses of the same space...

[Helen Bach]

Or to put in another way: The position of the lens determines the perspective, while the relationship between the taking angle and the viewing angle determines the compression/expansion effect.

Best,
Helen

[Ken Lee]

Here is a section of the Chicago image that was made with the short lens. Note that because the camera was not moved, the "flattening" is the same as with the longer lens. (It's a bit blurry, because that's all the pixels there were).

From the same position, the only difference between the 2 lenses, is angle of view.

[Mark Sawyer]

Uhhh... Don't know how you did it, but I think you got the wrong picture, Ken!

[Ken Lee]

You may be right, but I simply took a central portion of the 75mm on 8x10 image (http://i55.photobucket.com/albums/g139/Owen21k/chicagostorehypergon337hi810.jpg)
and sized it to the same size as the 75mm on 35mm image, (http://i55.photobucket.com/albums/g139/Owen21k/chicagostorehypergon337hi35.jpg). That size is 337x486 pixels.

Have I overlooked something ?

Attached is an image with both, side by side. As I mentioned earlier, the blurriness is due to the fact that the central portion of the wide-shot, is rather small: not a lot of pixels to deal with.

Blur aside, they are virtually identical, with regard to "flattening". If you squint a bit (and thus blur them both), you will see that it is the distance from camera to subject, which determines the apparent "flattening".

[Mark Sawyer]

Duh, I'm stupid! When you said "Chicago image" I thought you were writing about an image made in Chicago. I completely spaced out that it was the Chicago Store in my image made in Tucson!

Yes a 75mm will treat the space the same within a given format regardless. My point was that changing the format changes the angle of view, which affect how we see the overall space by including more space to see. It will also affect how we position ourselves to photograph a place. So it ends up being a "yes, but..." or a "no, but..." answer.

I'm sure we could clear it all up, if only we could get the candidates to talk about this issue in a presidential debate...

[Ken Lee]

"I'm sure we could clear it all up, if only we could get the candidates to talk about this issue in a presidential debate..."

Definitely ! ;)