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.
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91 Comments
Third Option for the poll is the best one.
Good read
Indeed.
Now this is a very nice post! Have been following this site, but now I had to register because of this one!
From my perspective, anyone who plans going into phorography more seriously should at least learn basic physics and optics as well, not to mention electronics and how every component of your gear works.
Nice one Lee!
"... from my perspective ..."
I see what you did there.
Thanks for that!
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[glass shatters]...
So...all of those that say that a 35mm on a crop sensor gives less compression than a 50mm on FF are wrong?
I wouldn't have believed it if I hadn't seen your test!
Great read!
If the cameras are in the same spot then the compression will be the same. The depth of field will not be though. In the example I used above everything is in focus so it's a non issue but telephoto lenses will produce shallower dof compared to a wide shot cropped in.
Unless, of course, you are using a faster WA on your crop sensor that offers a similar DOF as the longer FL glass on a FF. Such as, say, 50 1.8 on FF next to 35mm 1.4 on aps-c... the "look" you get will be similar enough that you could reasonably call DOF equivalent. Not the angle of view, but the DOF.
Good article, Lee, I got into this very same discussion last weekend at an air show that I was shooting with a 200mm next to guys with 600mm who claimed to have better "grouping" of Blue Angels because of "compression" their longer teles offered. We were shooting from the same spot ;)
"I got into this very same discussion last weekend at an air show that I was shooting with a 200mm next to guys with 600mm who claimed to have better "grouping" of Blue Angels because of "compression" their longer teles offered. We were shooting from the same spot ;)"
That is a fantastic example of a real world situation where this information is useful.
yeah I knew the depth of field would be different, glad you didn't shatter that glass too ;) haha
It's nice to know the theory! Still, on a crop, you need to get further away to get the same shot as a FF camera but at least we know it's the distance, not the lens, that affect compression.
In response to [ Jeff P. ] who suggests that we have to move to get the same shot when using different size sensors.
No, we cannot get the same shot by moving.
We can only get the same shot from the same position, by not moving.
If we move, we get a different shot.
There are reason to move, and there are reasons to stay.
Moving gets different shots.
Staying gets the same shots.
The only subject that will not change ( much ) when moving ( on axis ) is flat copywork.
For all three-dimensional subjects in three-dimensional surroundings, moving will get a different shot of the supposed main subject, a different shot of their surroundings, and definitely a different relationship between them and their surroundings
Thanks for exploring this and sharing.
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The angry photographer on YouTube is trying to dispute your article (not doing a great job to be fair).
Link?
https://www.youtube.com/watch?v=Wm6yxD4E5AM
I think he's misunderstanding the fact that although compression does exist LENS compression does not.
I responded on his video. Not sure it matters.
I agree it doesn't matter I just found it funny lol.
Paraphrasing [ Lee Morris ] "... the depth of subject field focus is lens-focal-length dependent ..."
Oh please do not go there.
All that different lenses do is change magnification in-camera, essentially cropping or stitching in camera instead of in post-capture-processing.
A different focal length lens cannot do anything else but change the magnification of the existent view of the subject scene.
If a lens changed anything other than magnification, no one would manufacture it, because no one would buy it, because it would be distorting.
Thanks for exploring this and sharing.
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Totally true. This is the article everyone needs to read. Its why a FF 35mm can be a great choice for portraiture. Just make sure your distance is the appropriate.
Since I'm the mood to "add" to others' comments tonight... I'd say make sure your distance is appropriate BUT ALSO your subject placement is too: you place your subject towards corners and you've got other things in perspective distortion to worry about more with a wider angle focal lengths.
Regardless of the semantics, the results are the same. This knowledge isn't going to replace the need for a wide or long lens to get a specific look.
That said, the more you understand the physics of photography and how your equipment works, the better.
« This knowledge isn't going to replace the need for a wide or long lens to get a specific look.»
But that is the point of this article, that people are being told to use a different lens and stitch for a different look, when they end up with the same look, had they used the correct lens. Changing lenses and standing in the same spot DOES NOT change the look, no matter how much one stitches or crops. The look is dependent on position only. Lens choice affects framing (until one decides to stitch or crop).
Lee, you're right as long as the camera position and lens axis doesn't change. Here's an old diagram related to Alberti's window: http://media.tumblr.com/tumblr_l34tqtKrO61qafpe7.jpg
In the diagram, the "center of projection" is the same as the camera position and the "principal ray" is similar to the lens axis plane. As long as the camera position and lens axis plane stay the same, then it doesn't matter what focal length lens is being in terms of maintaining perspective. However, if a photographer changes camera position (even without changing the lens axis plane) then he alters the distance to subject and the angle of the "projecting ray" at the bottom of the diagram. The angle of the projecting ray is what causes the sense of compression when changing the distance to the subject.
Basically, what I'm saying is that you're right and the part that confuses most photographers is related to the angle of the projecting-ray/camera-position rather than the principal-ray/camera-position.
You are right.. if you stay in the same spot relative to your subject there will be no more compressing at lets say 70mm than 24mm in this case it's only about framing. Only when you move yourself or the subject to have an equal size relative to the frame will you see more compression at 70mm than 24mm.
Basically this means if we'd have unlimited megapixels there would be no need for telephoto lens. We could just crop everything and it would have the same effect. However the other way around is a bit more difficult because it's pretty difficult to shoot a 4 by 5 room with lets say 200mm lens. It's a lot of work stitching all those files together and there'd be a problem with getting your lens to focus close enough.
I've always felt like compression was a bad way of defining it too. Just like how I hate when people say sensor size impact depth of field. It doesn't. Distance to subject does and the bigger sensor just lets you stand closer at the same focal length.
That said, in my opinion, the benefit of stitching a telephoto to create a wider "look" is that it helps reduce wide angle distortion and also lets you shoot at a much narrower depth of field than a wide angle would allow.
I maybe 100% off-base with this comment but it sounds like you are telling how to compensate for compression (by altering distance from subject) rather than saying there is no compression. Changing the variables of distance to subject and distance to background and saying you get the same result is like saying I can make 10+10=32 by changing one of the 10's to a 22 instead.
« Changing the variables of distance to subject and distance to background and saying you get the same result ….»
But he never said that. What he said is if the distance does not change, the result does not change, (regardless of lens, sensor, etc.), but if you change lenses and also change distance, then, because the distance changed, the compression has also changed.
The apparent compression between subject and object is a matter of the ratio of the distance from observer to subject, and observer to object. If the subject is 10m away and the object is 20m away, it would have the same amount of “compression” as when the subject is 20m away and the object is 40m away, (because 10:20 = 20:40 = 1:2 same ratio). That is, the object would appear to be twice the distance away.
In the case of the man and the mountain, one foot from the man, a mile from the mountain, and the mountain appears to be 1,609÷0.294=3,636 times the distance away. (One foot =0.294m, one mile = 1,609m). Moving back one more foot, we now have the mountain appearing 1,609.294÷.588 = 2737 times the distance away.
To get a real change in perspective, by moving 100m from the man, we now have 1709÷100 = 17 times the distance away.
To put it differently, by moving from one foot to two feet from the man, he now appears twice as small, (2÷1=2), while the mountain appears about the same size, (1609.294÷1609=1.0001872 times smaller, a change of less than 0.019%). moving 100m away, the man now appears 340 times smaller, (100÷0.294=340.1), while the mountain now appears 1.062 times smaller, (1709÷1609=1.062), or still about the same size, (at about 6.2% smaller).
All of this is regardless of the lens/sensor/post-crop, et al.
Or, in other words, if you frame the subject the same (moving closer for a short lens or further with a long) and your DOF matches then a photo taken with, say, an 85mm and an 11mm will look identical.
Nope, you got that wrong, unless your subject was flat, and there are no foreground/background objects). Once you move, perspective has changed, (compression has changed, etc.).
What he is saying is if you contact print a 10×8 inch negative, shot with a 300mm f/28 lens, and stayed in the same spot and shot the same scene with an APS-C camera with a 30mm f/2.8 lens, and enlarged the image to 10×8, then not only will you get the same perspective, (because you did not move), but the same framing (because you had the same FoV), and the same DoF, (because you had the same aperture diameter).
OMG we think as one!
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In your animated gif of the guy in front of the tree, when using the 200mm lens the tree is covering the entire frame behind your subject as opposed to the 24mm where it is barely visible behind him.
Because you had to use the long lens to achieve this look, even if it is because you also had to move the camera. This effect is caused because you are using a long lens creating a "compressed" distance between subject and background.
So while it may not be the actual lens doing the compressing, you can't say the lens has no affect on the equation.
and just as exaggerated are the facial features and brim of the hat the subject is wearing. That is the practical side of "compression"
Did you read the whole article?
Yup, even the part of your article that says "Compression is a real thing but it really doesn't have anything to do with a lens"
And as I said. The lens may not create the compression but it does have something to do with the final effect.
Actually the lens only has the effect depending on its position.
It's final effect is cropping.
Zoom from one position and crop to identical size (as in the illustration) and the image has the same "effect".
Yes, I read the whole article. So what would you call the exaggerated facial features created by a wide angle lens vs. the "compressed" look of the facial features taken with a 200mm lens? Most of us refer to it as compression but you seem to not want to use that term. ...Oh I see, you are not saying compression doesn't exist are you. You're saying the lens isn't responsible for it. Seems like a silly argument. I can tell when a person is photographed by a 24mm lens vs. when they are photographed with a 85mm or 200mm lens. The facial features look compressed with the longer lens hence the term compression I figured. I'll still refer to it as compression of the image regardless of the technical bs. Personally, I've never used the term "lens compression". Image compression sure, but not lens compression.
Yes, lens compression doesn't technically exist but perspective compression does. You may say this "is a silly argument" but a massive portion of the photography community doesn't understand this. A commenter above just said a guy went out to an air show with a 600mm lens rather than a 200mm lens because he liked being able to "compress the blue angels together." Obviously he doesn't understand compression and this article is for people like him.
No, it is the movement of the camera not the lens choice, If he had shot the 16mm lens from the same position as the 200mm lens and then cropped the image to the dimensions of the 200mm, the field of view and the tree in the background would look identical.
But if you really want to get pedantic you could say that your distance from the subject is "caused" by the length of your lens so there is a causal relationship between lens and compression, but not a physical.
Incorrect, the angle of view and level of magnification in the lens means that the background will be different between the wide and tele lenses shot from the same space if the wide is cropped to give an equivalent framing of the subject. Lets say you shoot a headshot at 200mm, if you then take the 200mm off the camera and replace it with a 24mm and take the same shot from the same location, the wider angle of view will "expand" the background behind the subject so that even if you crop in to the same framing, the background shown behind the subject will be different.
Nope. That's exactly what I thought as well. Great post on Fstoppers.
Timothy, that is a double incorrect :)
If you stand in the same spot, you could change focal length all day long and it will be no different from cropping. The only two variables that can affect the size of the background relative to the focused subject are aperture and camera to subject distance.
Try it yourself with a zoom lens and you will see the results very quickly...
I can say the lens has no effect on the equation, and i would be right if the equation had no location for "resolution" in its problem.
So here it is: "the lens has zero effect on compression if resolution is of no concern".
Now since as long as i can recall, resolution is very much at the forefront of many photographers list of things they want. So in that regard, compression, very much has everything to do with lens choice, if resolution is a primary concern.
Forget resolution. No novice to photography is being taught, “here is how you get resolution to make a great image.” What they are taught is perspective, (choice of position), and framing, (choice of lens:film width).
When a landscape photographer chooses to go with a wide lens, does his “resolution” suffer? No. The resolution of the distant tree may suffer but that is immaterial to him. What matters is whether the tree is in a good position relative to everything else, (perspective), decided by his position, and where in the frame (or how much of it is in the frame) relative to everything else, (focal length).
The same is true for a sports photographer, (except, depending on the sport, he may not get much choice in composition). He chooses his position first, (composition), then he chooses his focal length (zooms appropriately), before shooting (framing).
Ultimately, your position/composition dictates the compression, your focal length dictates your framing, your camera manufacturer determines your resolution. If you want greater resolution, buy a different camera.
Great article Lee, I'd never thought that far into it before and always assumed it to be an effect of the lens. Consider my mind changed.
Lee,
The words you're looking for are "Perspective Distortion". ;)
Ding! We have a winner, thank you [ Timothy Tichy ] for writing
"... The words you're looking for are "Perspective Distortion" ..."
Yes.
Distortion is the difference between input and output.
What we have here is the difference between
-- the input angle of capture
-- and output angle of presentation.
Keep them the same, and there is no perceived distortion.
Change them, and there is perceived distortion.
It really is as simple as that.
Thanks for exploring this and sharing.
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PS, I've been writing this for years, as Ansel Adams also preached it once he figured it out, here's one of mine from 4 years ago, I have more that go -w-a-y- back:
https://learn.zoner.com/prime-lenses-one-focal-length-many-benefits/#co…
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The poll is even 50:50
The biggest revelation in 2016. The longest running myth is finally demystified.
Oh boy... just scrolled through comments. Lazy is a good way to summarize everyone trying to debate this concept. There's A LOT of very clear studies from the academia that debunk this very phenomenon and go into much deeper science to essentially prove the point of the article.
All variables, including camera distance/angle from the subject/background, being equal give you the same "compression" no matter the focal length.
Mind blown😵
The poll shows 50% of photographers didn't know this