A telephoto lens “flattens” or “compresses” the background, have you heard? What does this mean exactly? Both where you stand in relation to your subject when taking the photo and the focal length of the lens you use determine the perceived distance between your subject and the rest of the scene. I’m going to talk about how to use perspective distortion in photographs in this short article.
1. What Lens Compression Isn’t !
Using a telephoto lens, photographers claim that the distance between the subject and the background appears to be shorter in their photos than when using a wide-angle lens. The opposite is true. The perceived distance from front to back will be the same in two photos taken from the same location with different lenses, even if the focal lengths are different. This is because the perspective has not changed! Make an image with a wide-angle lens the same size as a photo taken with an 85mm telephoto lens to see this. The crop quality will be terrible, but that’s beside the point. The idea is to have the crop look exactly like the original telephoto shot.
Look at these two pictures for a moment. The first picture was taken with a 24 mm lens, while the second picture was taken with a 70 mm lens. Both images were captured using a tripod and the same vantage point, with the same focus on the bridge in the middle of the frame.
24-70mm f/2.8 @ 24mm, ISO 100, 1/500, f/8.0
24-70mm f/2.8 @ 70mm, ISO 100, 1/320, f/8.0
Now I’ll crop the wide shot to match the telephoto shot’s composition. To make a fair comparison, I had to increase the crop size by about 285%, which isn’t something I’d normally suggest. Take a look at how similar this crop is to the original image taken at a focal length of 70 mm. The fishing pier’s railing (on the right side) is still in the same place, and neither has the bridge. To put it another way, the longer focal length had no effect on distortion or “compression”.
24-70mm f/2.8 @ 24mm, ISO 100, 1/500, f/8.0
The only distinction can be found in the focal length of the lenses. The photo taken at 70 mm has a less-than-sharp foreground. What we’ve learned is that depth of field is dependent on a number of factors besides just aperture size.
The most important thing to remember is that the subject’s distance from the camera remained constant. The image’s proportions remained unchanged as a result. A telephoto lens has the same effect as cropping if your feet don’t move during the shot. However, you won’t lose any detail or sharpness in the process.
2. What Is Lens Compression ?
Now tell me, what exactly is lens compression. When using a telephoto lens, you will experience lens compression, but this is not due to the lens or the focal length of the lens. It’s because when we use a long lens, we tend to stand further away from our subjects. When using a long lens and focusing far away from the subject, the viewer will be led to believe that distant objects are much larger. Consequently, the background seems to be getting closer to the subject. When you use a wide-angle lens, the opposite effect occurs. When shooting with a wide-angle lens, we get much closer to our subjects than when using a telephoto one. Near objects will appear proportionately larger than distant objects due to their close proximity. To compensate for this reduction in size, the foreground elements now appear far away.
Here are two illustrations of this. I used a long lens for the first shot. Take a look at how close the freighter appears to be to the flying creatures. They were only a few hundred meters apart in reality.
200-400mm f/4 @ 380mm, ISO 800, 1/1250, f/5.6
I used a very wide angle lens to capture this image of a goat. The goat’s large head stands out against the rest of his lean frame.
10.5mm f/2.8, ISO 400, 1/640, f/8.0
It’s not so much that I used different lenses as it is that the distance between my subject and the camera was vastly different in each shot. At a distance of about 100 meters, I took the photo of the birds and freighter. My camera was only a few inches away from the goat’s nose when I took that picture.
Although the last two examples don’t really illustrate the concept of lens compression, that’s because they depict two completely different things. Let’s take a look at some pictures to see why compression occurs. I tried to keep the subject (my very cooperative and patient daughter) the same size in all of these images. As the focal length got longer, I had to get farther away from her to get the shot. It’s important enough to say again. To keep her the same size in the frame, I had to change the distance between her and the camera. Focus on what’s going on in the distance. A quick note about photography: I am not a portrait photographer, so no criticisms of the lighting or posing!
The focal length used in the first image is 24mm. Just look at how much space there is behind them; it helps to establish a sense of scale for the viewer. Take a look at the flag and the flower planters to see how far away they appear. Due to my proximity to my daughter, her nose appears disproportionately large.
24-70mm f/2.8 @ 24mm, ISO 100, 1/500, f/5.6
This next shot was taken at a focal length of 70mm. The flag appears larger. Also notice what is happening to the trees in the background. They seem closer, as do the planters.
24-70mm f/2.8 @ 70mm, ISO 100, 1/400, f/5.6
105mm. You can no longer see the flag. The cherry blossom trees are becoming more prominent.
80-400mm f/4.0 @ 105mm, ISO 100, 1/400, f/5.6
My focal length is now 200mm. The background is getting even closer still. It is very hard to get a feel for distances now.
80-400mm f/4.0 @ 200mm, ISO 100, 1/320, f/5.6
This final image is taken at 300mm. The planters were about 10m apart in reality, but look how close together they appear now.
80-400mm f/4.0 @ 300mm, ISO 100, 1/320, f/5.6
The distance between the camera and the subject is what causes compression. Because of the narrower field of view provided by longer focal lengths, you will need to step back to maintain the same overall size of your subject. A wider field of view is provided by a wide angle lens. You must get very close to your subject if you want to keep its size constant in a wide angle image. The distance between my daughter and the background did not change as I changed focal lengths; it was the distance from the camera to her that changed.
Put another way, think about it like this. When something is in close proximity to you, it appears larger than it actually is. When you are twice as far away from an object, its size is halved. If you increase the distance by a factor of ten, the object will shrink by a factor of ten. There’s less distance between me and my daughter in wide-angle photos because her background is farther away. Lisa, on the other hand, is a lot bigger than the trees (as objects appear smaller with distance).
When using a telephoto lens, Lisa and the background appear closer together due to the fact that they are separated by a large distance. As I increase the distance between her and my camera, the distance between her and the background becomes less significant.
3. Lens Compression And Composition
Once you realize that the distortion is caused by the distance between the camera and your subject, you can use lens compression to your advantage. Use a long lens and step back from your subject when taking a portrait if there are a lot of distracting elements in the background. By taking a step back, you’ll be able to focus on just one thing in the background instead of the whole mess.
Focal Length 420mm – Aperture ƒ/7.1– Shutter Speed 1/2500s – ISO 800
If you want to convey the vastness of a landscape, use a wide-angle lens to get close to a foreground subject. This will make distant features appear even more impressive.
Focal Length 20mm – Aperture ƒ/16– Shutter Speed 0.3s – ISO 100
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To summarize, the farther away the background appears, the closer your camera is to the subject. This will make the distance and size differences between the foreground and background appear larger. As you back away from the subject, the distance between the foreground and background gets smaller. Put your subject in close proximity to a distant background using this technique.
Consider the distance between your camera and the subject when you’re composing your shots. Try moving your feet instead of just zooming in and out on your lens! Opt for a wide angle or a telephoto lens depending on how close or far away you want to be to your subject. Try out this technique and see how it affects the flow of your images! Enjoy yourself while you’re out there!