To those who argue that telephoto compression is all down to distances:
Suppose the scene in front of you is a long straight road with one vehicle 100 yards away, another vehicle 300 yards away, another 400 yards away and a fourth a mile away. If you take a shot from your present position, will it show telephoto compression?
From the Wikipedia article:
"Perspective distortion is determined by the relative distances at which the image is captured and viewed, and is due to the angle of view of the image (as captured) being either wider or narrower than the angle of view at which the image is viewed"
If the angle of view of the image (as captured) is wider than the angle of view at which the image is viewed, wide-angle perspective distortion is seen.
If the angle of view of the image (as captured) is narrower than the angle of view at which the image is viewed, telephoto perspective distortion (more commonly called telephoto compression or lens compression) is seen.
Note that the angle of view at which the image is viewed depends on the viewing distance (relative to the size of the image).
(Unfortunately, that Wikipedia article, like many, also contains some incorrect and nonsensical statements.)
Another source of information about perspective is very old textbooks. Here are a few excerpts from " The Manual of Photography" (7th Edition, 1978):
The Manual of Photography, from which these excerpts are quoted, was first published in 1890 as The Ilford Manual of Photography. Early photographers had a very good understanding of perspective. It is sad that perspective is so poorly explained by many modern tutorials on photography.
No, obviously not 'tele'. You missed the next image and its description, and quoted a part of my message out of context.
In the OP you claimed that the compression had nothing to do with the physical distances from the camera to the objects:
That's wrong on at least two levels: first, the compression is indeed due to distance; second, 'lens compression' is a misnomer, but as long as you use it, why do you call your perception of perspective when viewing a photo a 'lens compression'?
I was asking about this image, not the next one. So, you agree that it does not show telephoto compression. Are you implying that it shows another sort of compression? If so, please explain what determines if a shot shows your sort of compression.
My position is very simple. A shot shows telephoto compression if it was taken with a longer than normal focal length and is viewed in the normal way. The degree of compression is equal to the focal length divided by the normal focal length.
Of course, the shot must be of a suitable scene for it to show any depth at all. If there is no apparent depth in the scene, it cannot show telephoto compression.
Definitions:
Normal focal length is equal to the length of the sensor diagonal (43mm for full frame).
Normal viewing is viewing from a distance equal to the length of the (uncropped) image diagonal.
Please state precisely how you would define your sort of compression.
Please read the description. It can't be 'telephoto' because it wasn't a tele lens (it becomes a 'tele' when we do a heavy crop, simulating an effect of a longer lens).
Despite being wide angle, does show the compression, yes - you see, at a distance the screwdrivers appear of almost the same size and the apparent distance between them shrinks - unlike the wide angle image #2.
Again, the ratio of apparent sizes of objects get closer to the ratio of their actual physical sizes, as the camera moves away from the objects. Apparent distance between the objects along the line of sight also shrinks, which makes it harder to estimate the distance.
It doesn't depend on the viewing distance from the photograph and it doesn't depend on the focal length of the lens.
So if normal focal length is 43mm, and we shoot at, say, 85mm, the degree of compression is ~2?
What you're describing is just classic magnification against normal human angle of view. Which was pointed out already in the thread. I'm not sure why you needed to call magnification 'compression'.
I did it a couple of times already, including this very post.
I am sorry, but I do not understand how to apply your 'definition' to other situations.
For example, suppose you are standing beside a long straight road. There are vehicles 100 yards away, 300 yards away, 400 yards away and 1 mile away. If you take a shot from this position, will it show compression? What about if the vehicles are 1 mile away, 3 miles away, 4 miles away and 10 miles away? What about if the road is empty? What about if you stand in another position?
I really don't understand when you will see your sort of compression and when not.
A study found out that a typical viewing distance is not normal by your definition.
Yes, that's why 'normal' viewing distance is defined. Obviously, you can view from any distance you like. Normal viewing distance gives the correct perspective when viewing a photo taken with normal focal length. See my earlier post with quotes from The Manual of Photography.
Are they really “normal”? My normal viewing distance is determined by the distance my glasses focus, which is the case with many people wearing glasses, I guess. In particular, it is independent of the size of the print unless it is a poster size.
BTW, religious beliefs can be backed up with quotes as well. I heard that there is a book about that…
I think that was the 35mm Photographers Handbook - Julian Calder & John Garrett
A copy of which I still have somewhere
Andy
How do you apply your definition? You described magnification and called it 'compression'. A lens focal length divided by 'normal' focal length is magnification against the field of view from that normal focal length.
Your definition doesn't provide that either. By your definition, is the image compressed at 44mm? at 46mm? at 49mm?..
Good example with the cars by the way. When you see other cars at a distance on a hilly highway, sometimes you only see the tops of the cars and you can't discern which car is closer to you. Another simple example - airshow, sometimes you can't tell which plane is closer to you. And you don't need a tele lens or binoculars in order to experience that effect.
I wish I was home so I could post the wide-angle view of the scene I posted above, shot from the same position...
I found I needed to take a variable out of the consideration of all this for the effect to be understood, and that was position. From a particular position, a scene splayed out in front of a viewer has a particular perspective. You change that perspective when you move around. Nothing else can be used to change perspective.
Now, from the same position, all a telephoto lens does is to "crop" a part of that scene you'd record with a wider angle lens at the same position.Things look "compressed" because you're looking at an image made from just a small part of the scene.
This is why "zooming with your feet" doesn't render the same view as actually zooming in with a lens...
Congratulations! That is a textbook example of diversionary tactics that people use when they do not wish to admit that they are unable to answer the question.
Yes, spot on. "Lens compression" is simply the appearance of background objects being closer to the foreground objects when, from a given position, you zoom in.
What the others are talking about is how you can move around while using the lens compression effect to create different looking photos.
You ignored my answer or didn't understand it. Also you ignored my questions, is that another textbook example?
Why do you think the compression has to be either on or off?
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It's the magnication resulting from zooming in from a given position that causes the lens compression effect. Nothing is physically compressed.
I did not see any answer to my question. Instead you asked several questions of your own.
If someone answers my question by asking a lot of other questions, then I do ignore those questions. They are just trying to divert attention away from my original question (a standard Donald Trump technique).
It does not have to be either on or off.
There is a degree of compression, as I said earlier in this thread, which is equal to the focal length divided by the normal focal length (with the usual assumptions). Distances appear to be compressed by that factor. So if you use a focal length that is ten times normal, distances to the viewer (when the image is viewed normally) appear to be one tenth what they were in reality.
If the focal length divided by the normal focal length is less than one, the picture shows wide-angle distortion instead of telephoto compression (again providing that the picture is viewed normally).
I don't think anybody here claimed something was physically compressed.