longer lenses perspective

[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.

[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:

[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/g1...on337hi810.jpg)
and sized it to the same size as the 75mm on 35mm image, (http://i55.photobucket.com/albums/g1...gon337hi35.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".