How to shoot background blur

Lead: I believe that everyone who studies photography has a special liking for photos with clear subject and blurred background. So today I will tell you about the principle and shooting method of background blur effect.

To put it bluntly, the blurring effect of the background is the depth of the scene. The depth of field means that the plane you focus on (there will be a plane, and every point on the plane is the same distance from your camera) is clear in the picture. At the same time, there is still a distance before and after this is clear. This clear distance is called depth of field.

You focus with a camera, focusing on a point. In fact, the lens measures the distance from this point to your camera. There is also a ranging window on the lens of the advanced point of SLR camera, and the micro-single camera may have a digital prompt of the focusing distance. So the focus is on. To put it bluntly, the camera found this distance. Simply think about it, and you will know that there may be many others besides what you are concerned about at this distance. These others must be correct and clear.

Depth of field means that not only things at this distance are clear, but also things within a certain distance before and after this distance are clear. This is mainly because things beyond this distance will blur, but they will gradually blur. Within a certain distance, the degree of this blur will not be distinguished by the human eye, so it looks very clear.

After understanding the concept of depth of field, I think everyone understands that if you want to blur the background, you must try to keep the background out of the depth of field.

Want to blur the background, in fact, I summed up four formulas:

The background is far, the camera is close, the aperture is large and the focal length is long.

Far background

If you shoot a girl, you will definitely like the blurred background. The most direct way is to keep the background away. The farther away the background is from the girl, the more blurred it must be. This truth is simple enough.

If you shoot a girl, you will definitely like the blurred background. The most direct way is to keep the background away. The farther away the background is from the girl, the more blurred it must be. This truth is simple enough.

Camera proximity

The so-called camera is close, that is, the camera is closer to the subject. The closer the camera is to the subject, the shallower the depth of field, and the more obvious the background blur effect. This is better than the other three tricks. So when someone says that it is difficult for a mobile phone to shoot a blurred background, I say you try to shoot a coin with your mobile phone. If you get closer, the blurred background will be very virtual.

But there is also a problem. I wanted to take a full-body photo of a girl, but when I got closer, my head got bigger and even my eyes were close-ups. So in fact, the effect of background blur is mainly the latter two measures.

If you can take close-ups, the fact that the camera is close makes the most obvious contribution to the blur. For example, as soon as the F2.0 large aperture is opened, only the focused F card is real, and everything else is empty.

Another example is this cat, because it is relatively close, so the blurring effect is also extremely obvious.

But it's not good to shoot girls so close. Watch the next move.

Large aperture

Do you know the principle of pinhole imaging? Pinhole can become a real image, but it is not impossible to image when the hole is big, but it can only be a virtual image. This is why the background blur effect is more likely to occur when the aperture is large.

Therefore, when you want to blur the background, you should open the aperture to the maximum.

The large aperture background is blurred, which is basically known to everyone.

How big is the aperture? The above picture was taken with the aperture of F 1.2, and the following picture was taken with the aperture of F 16. The difference is obvious.

In fact, the background blur is also related to the focal length. The larger the aperture, the more obvious the blur. The longer the focal length, the larger the aperture and the more obvious the blur. So let's talk about focal length.

focal distance

The short focal length is a wide angle and the long focal length is a telephoto. Generally speaking, when we say portrait lens, we all mean 85mm focal length. This is a medium telephoto.

Other things being equal, the longer the focal length, the more obvious the background blur effect. Therefore, when taking portraits, it is better to choose medium telephoto as much as possible. Why not say the longer the focal length, the better? How far should I shoot if the focal length is too long? Shout loudly when communicating with models. Hey ~ girl, pull down your clothes and spread your legs a little more! ? Not appropriate, is it?

Therefore, as long as the background blur effect is remembered, the medium telephoto lens with large aperture is basically suitable. If you want to keep exploring, keep reading.

If you want to take a good photo, you should start with the aperture and focal length to achieve the effect of blurring the background.

What is the aperture?

The aperture is a ratio, which is the ratio of the focal length to the effective aperture diameter of the lens.

The focal length is written on the lens. So when the aperture and focal length are combined, you will find? What is the effective aperture diameter of the lens? This matter can also be determined as a numerical value.

What is the effective aperture diameter of the lens? To put it bluntly, it is a hole, which can be regarded as a pinhole imaging hole. The smaller the hole, the larger the clear distance, and the larger the hole, the smaller the clear distance.

So big holes and small holes are the real reasons that determine the blurring effect of the background. A large aperture lens means a large aperture.

For example, if a hole with a diameter of 50mm is placed on a 50mm lens, the aperture is F 1.0, which is quite large. When it is placed on a 200mm lens, it is F4. 200mmF4 doesn't feel great, does it? But I tell you, because they are all holes with a diameter of 50mm, the background blur effect is the same!

This is why a telephoto lens that you don't think is a big aperture can achieve such a strong background blur effect.

So there is an artifact called 200mmF2.0 lens, which is available in both Canon and Nikon, and Nikon's is even called air cutting machine. What effect is this? 200mmF2.0 is equivalent to 100mmF 1.0, 50mmF0.5 and 24mmF0.24, so when you see 35mm1.4, don't think that F 1.4 can be empty, which is only equivalent to 70mmf2. When you see 135mmF2.0, don't think F2.0 is small, and the blur effect can leave 50mm lens seconds without residue.

However, the telephoto lens has a long focal length, so you will be a little farther away from the photographer. This, this and the second formula? Close? There is a conflict, so it will offset some of the background blur effect, but the blur effect is still obvious.

The blur effect brought by telephoto is very obvious, that is, it is far away when shooting.

So remember! The four formulas of fuzzy background are:

The background is far, the camera is close, the aperture is large and the focal length is long.