Recently I've concluded that most professional photographers actually believe that telephoto lenses compress the subject and background in an image and that simply is not true.
I got a call from a local photographer last week. He knew that I had recently filmed a tutorial on architectural photography with Mike Kelley and he had a question about lens distortion. While he was photographing a home interior, another well known and successful architectural photographer in the area approached him and offered to give him his "secret technique" to produce distortion free images. Instead of shooting one vertical 17mm image (which has significant distortion in the edges because it's so wide), he suggested that my friend shoot three horizontal shots with a 50mm lens while tilting the camera from top to bottom and stitching the files into one photograph. My friend was shocked by the simplicity and potential of this suggestion and called me to confirm it. "Is it really possible to get distortion free images this way?" He asked. No it's not. In fact the images will have an identical field of view.
This was impossible for my buddy to believe so he had to put it to the test, and after comparing the two shots he found that I was right. The wide angle shot looked identical to a stitched shot created with multiple images from a longer lens taken from the same location.
After the test he called me to tell that the distortion was indeed the same but he was still convinced a longer lens would produce more "lens compression" meaning that the foreground and background objects would appear closer. I then blew his mind for the second time; "You realize that if you take a portrait of someone with a telephoto lens and then take the exact same shot with a wide lens from the same spot but crop into that image, the 'compression' will look identical," I said. My buddy simply could not believe this to be true. He had always been taught that the lens was doing the "compressing." After quizzing a few other photographers I realized that the majority of professional photographers I know didn't understand this either.
Lens compression has nothing to do with the lens and has everything to do with your distance from the subject.
I explained to my buddy that lens compression doesn't happen in the lens, it happens when you physically move the camera back. No matter how I explained it he wouldn't believe me until he did the test himself.
Why do we use the term "lens compression?"
Most photographers believe that the lens is "compressing" the scene because they will take a test shot with a wide lens, and then back up to capture a similar composition with a telephoto lens. It's easy to see that the telephoto shot is far more "compressed" and it's also easy to completely overlook the fact that the camera has been moved and the field of view has changed.
Why does compression happen?
Imagine you are photographing a person and behind that person is a mountain. Let's say your subject is one foot away from the camera and the mountain is one mile behind your subject. From this distance the person's face would look huge compared to the mountain because the person is exponentially closer to the camera than the mountain.
To make the person half the size that they currently are in the frame, you would have to move back only one foot, doubling the distance of the camera from the subject. But when we half the size of the person by moving back one foot, the size of the mountain remains almost identical because to make the mountain half the size you would need to move the camera back one mile. This ratio between the distance of the subject and background to the camera is what causes compression.
As you continue to move backward your subject will get smaller and smaller and the mountain will remain about the same size. To keep the subject the same size in the frame, you will need to zoom in using a lens or "crop in" in post and as you do, you are enlarging both the person, who has been shrinking as you back up, and the mountain, that has remained basically the same size.
When we look at the final images it may appear that the person is the same size in each picture while the mountain is growing but in reality the opposite is happening. The mountain is staying the same while the person is shrinking and we are zooming in to compensate.
Here's Proof
In this gif below you can see two images that Elia Locardi took during the filming of his landscape photography tutorial. In both shots, the camera was in the exact same place on a tripod. The image on the left was taken with a 16mm lens and the image on the right was taken at 145mm. Notice that when we "crop in" or "digitally zoom" the wide shot, we can get an almost identical looking image to the shot taken at 145mm with the exact same "compression."
Conclusion
Compression is a real thing but it really doesn't have anything to do with a lens. It has everything to do with your distance from the subject/background. You could get a shot with identical compression if you stand in the same location and take a photograph with a telephoto lens, a wide angle lens but crop in, or a camera with a "digital zoom." The magic isn't in the lens, it's in simply backing up.
And all of this leads back to the very beginning of the article. Is it possible to create a distortion free image by stitching multiple telephoto images rather than using a wide angle lens? No, because the distortion/compression is caused by the location of the camera in relation to the subject and not by the lens. If you stitch multiple images you'll end up with a higher resolution shot that has identical compression.
This does not mean that telephoto lenses are obsolete. Long lenses allow us to back up and zoom in without losing resolution; everyone knows that. But this post simply explains the phenomenon of compression in general which many photographers do not fully understand.
Take the poll
In talking with my photography buddies about this I've discovered that most photographers do not seem to know this. I'm curious how many of you reading this also didn't know that lens compression doesn't really exist. Take the poll below and let's find out.
Hallo to all friends.
Compression have to do not only with the lens, but with cooperation with size of a sensor.
A 55mm lens give always the same perspective or compression but this lens is wide angle in medium format while in small one is tele. To understand this aspects and their results of why the picture of small formats look so flat and distort compared to pictures of bigger formats read this informative and easy understandable article:
http://www.bokehblog.com/photography/post/Medium-Format-vs-Full-Frame-vs...
Hi, first of all congratulations for the hi level discussion instead of talk about begginners talk.
You're very right about the fact that the wide angle lens and the tele photo lens do the same bokeh, when you crop it you can see.
About the distortion with wide angle and multiple zoom shots you're right too, but just if you stop the technique at this point, but if you do that so that's incomplete.
When you have one single shot with a Nikon D7100 with an wide angle you will have a 6000x4000px image and if you correct the distortion on the photoshop you will lose quality.
But when you do that with multiple images you can have an image up to 10.000x10.000px, then you can make the distortion correction on the photoshop, reduce the scale to 6000x4000px and then you have no loss of quality. That's the complete procedure.
You're technically correct, obviously. But here's the thing. The traditional way of thinking about it is arguably more useful in practice. Sure, I can get the same effect by using a wider angle lens and then cropping. But do we really want to get in the practice of not attempting to composite our photos the way we envision the final photo in camera? If I want to take a full length portrait of somebody, I'm going to compose it that way whether I'm using a 200mm lens or a 50mm lens. I'm not going to take a photo of a bunch of stuff I don't care about and then crop it to what I want.
And let's make no mistake, it is VERY wasteful to do so. Final resolution varies with the square of the difference in focal length. So if I use a 30mm lens from the same spot I'd use my 300mm lens (10x the focal length) and crop I might have the same composition, but instead of a 24 megapixel photo I have a 0.24 megapixel photo (1/10x1/10= 1/100 the resolution).
Even on more modest examples make a notable difference. 50mm vs 100mm will yield 1/4 the resolution, so 6mp rather than 24.
So yes, if I use a 300mm lens rather than a 50mm lens I will get more compression. Because I'm most definitely (and rightfully) going to go further away from the subject to compose my photo.
«The traditional way of thinking about it is arguably more useful in practice.»
I agree with that, but I think you do not really know the “traditional” way. I'll explain later.
«But do we really want to get in the practice of not attempting to composite our photos….»
Here you are confusing “composition” with “framing.” Composition is a direct result of where you stand, relative to the subject. Framing is what you do by choosing your focal length. If you choose your focal length first, then try to “frame” by “zooming with the feet,” you are altering the composition. [HINT: one cannot “zoom with the feet.”]
The traditional way is to first move around your subject (on all three axes) to find the right composition, then choose your lens to frame it.
In that gif, they are mantaining the aspect of the face in the frame, and moving back as they increase the lens length. Made that for showing that is the distance that changes the compression.
Maybe a bit confusing.
It is compression, as a result of moving away from the subject, not from choosing a focal length. The position dictates the composition/perspective/compression, the focal length selects the framing of the subject.
I´m a bit late for this article but it just blew my mind...
I´m super confused now... I always believed that if I wanted a more compressed, more flattened, less distorted image, I would need a bigger sensor. But it turns out that is just the opposite! The cropped sensors are the gods of compressed images then; for a given field of view, with the same lens length, I would need to get further as the sensors size decreases, compressing the image. (This is a real world example I can think of, as I can share lenses between 35mm and APS-C cameras)
I suppose then, that the medium format "look" is more related with lenses quality and the narrower dof. For the same fov, the longer the lens, and the less ditorted it is (talking about lens distortion, bad distortion, not perspective distortion).
Super cool article. Thanks.
Btw, I think most of the bad comments are related with that gif, showing the effect of the distance + the focal length, matching the framing and changing the compression. You should make your own gif, keeping the distance and cropping to mantain the framing to compare. Or at least write a comment below that gif explaining what it is being shown.
Neither.
Neither the lens nor the distance is doing the apparent compressing.
The viewer of the final presentation is doing the apparent compressing.
If the final presentation is presented with the same angle of view as it was taken,
then there will be no compression perceived.
What we are noting is is total system distortion,
a difference between
-- the taking angle of view
-- versus the angle of view of the final presentation.
If the angles are the same,
then there is no compression,
regardless of the distance from the photographer to the subject,
regardless of the type of lens used, wide angle, normal, or telephoto.
Thanks for exploring this and sharing, especially in the "I have a buddy" format.
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Absolutely great article and shows real understanding of optics and perspective. Angry Photographer is just often plain annoying and rude as opposed to someone trying to figure out if for example a 20mm excellent lens with cropping a bit can substitute a poorer 24mm in a pinch. Thank you for addressing real photography questions in such clear terms.
Thank you for a great article that is very relevant to numerous photographic situations like exploring perspective compositions and also creative choice of lens and distance. But some guys need a refresher in photography tutorials and or prescription in medication to understand straightaway.
So how to achive with wide lens that gigantic moon look, where people in front of it are small, or tiny lighthouse in front of gigantic wave? What do you call this? Or why in close proximity, faces change from narrow to wide, when wide to tele are swapped. Please elaborate. Thanks