How to shoot high-quality images with ordinary lenses?

I always think the camera should be good enough. Besides, it's cheap enough! For example, there should be a lens with a focal length of 18-200mm, a constant aperture of f 1.4, and anti-shake and macro functions of 1: 1. Such a lens should be affordable to the public. However, this is impossible, not because the designer has no technology, but because the manufacturer has no profit. Businessmen always do this: on the one hand, the products they offer you should be good enough for you to pay, on the other hand, they should not be good enough for you to pay all the time.

In most cases, the reason why photographers start to "have a fever" and spend a lot of money to "burn" equipment, so that they finally cultivate to the degree of "gray" is just a "trick" of businessmen.

When I was writing this pile of words, I don't know how many photographers in the world are trying their best to find a more suitable excuse and more money to upgrade their equipment. However, due to financial constraints, most of these brains will eventually suffer from helplessness and die a considerable number of brain cells.

Let's not do such unnecessary things. Now, let's take a look at how to get a clear and wonderful image through the magical light.

First, use an appropriate aperture to obtain a high-quality image.

In photography, lens aperture control is one of the most important basic skills. Because the aperture value can affect the depth of field effect, shutter speed, imaging style and imaging quality! However, the influence of aperture size on imaging quality is mainly discussed here.

Generally speaking, using the maximum or minimum aperture of a lens can not get very satisfactory imaging quality! When the aperture is fully opened, the light will pass through almost the whole area of the lens and form an image on the photoreceptor. In this way, the defects (scale errors) caused by insufficient precision in the lens production process will be exposed in the final image.

Therefore, we narrow the aperture so that only a part of the central area of the lens, not the whole area, passes through the light participating in the imaging. In this way, the manufacturing error of the opaque part of the lens edge has no chance to destroy the imaging quality, so the imaging quality has been improved to a certain extent. So according to this theory, the smaller the aperture (same lens, same focal length), the better the imaging. But in fact, we will encounter another problem: if the aperture of the lens becomes too small by narrowing the aperture, the diffraction phenomenon of light passing through the aperture will be very serious. And this optical phenomenon will also reduce the imaging quality of the lens!

Because aperture value = aperture diameter/lens focal length, a smaller aperture is also used. The shorter the focal length of the lens, the smaller the aperture will be. According to this relationship, it is easy to find that the shorter the focal length of the lens, the easier it is to reduce the imaging quality because of the diffraction of light when taking photos with smaller aperture. Think about it. Even if the aperture value of a lens with a focal length of 300mm drops to f32, its aperture size is exactly the same as that of a lens with a focal length of 30mm and an aperture of F3.2.!

Knowing this, we don't always have to care about the "general experience" mentioned at the beginning. For example, I have a 70-300mm lens in my hand. I specially tested its imaging quality at 300mm end, and the result is that the smallest f29 and f32 are the best apertures!

Second, the shutter speed will also affect the imaging quality of the lens.

First of all, I still want to say a "general experience", that is, if the shutter speed is expressed by 1/M seconds, the lens focal length of 135 camera is expressed by n mm. Then when shooting with a hand-held camera, it is generally believed that m needs to be greater than n, so that the image will not be blurred because of hand jitter. It is also more strictly proposed that m should be greater than 2N to ensure the clarity of the image.

In fact, the above "general experience" is not directly related to this article, because this article is completely around the lens, and it also distinguishes between high-end lenses and cheap lenses. However, due to the above-mentioned "general experience", many people blindly pursue faster shutter speed. When they expect to get a clear image, they always think that "even if it is only a little faster, it will be clearer." This is a problem!

As we all know, SLR cameras have a weakness: at the moment of shooting, the movement of the reflector will make the whole camera vibrate, which will lead to blurred images. In order to solve this problem, the designer added the function of pre-lifting mirror to some high-end cameras, which effectively avoided the vibration caused by the mirror. However, most cameras still don't have this function. Of course, it is the same sentence: not because there is no technology, but because there is no profit! My digital SLR body cost 6000 yuan, but I still haven't got it. ! At this time, only we have to find a way. This paper mainly discusses the telephoto lens, because according to the similarity ratio in geometry, telephoto lens will amplify the vibration of the camera and aggravate the blur.

High-end telephoto lenses are often heavy and equipped with special brackets. The former is like shooting with a heavier gun, which is more stable and easier to shoot. Gravity cushioned the vibration. And according to my experience, it's the same whether you shoot with your hand or use a tripod. The latter allows us to use a tripod, and the whole camera can be in a more stable state, which of course reduces the vibration amplitude. But with ordinary cheap lenses, the situation is completely different: the mirror body is light but not strong, although it is long, but there is no special bracket. When shooting, the camera is completely connected to the tripod head by the fuselage. It just looks extremely unbalanced! At the moment of shooting, we can observe the obvious vibration coming from the frame, and even hear the sound from various parts of the lens because of poor combination! At this time, the imaging is naturally unclear.

But don't be depressed, I'll tell you now, you can also take clear photos with such a lens! The methods are: adding PL filter, adding ND filter, reducing the aperture and reducing the sensitivity (ISO). . . In short, try to reduce the shutter speed as much as possible, instead of improving the "general experience"!

The reason for this is to extend the exposure time as much as possible. Because the vibration of the mirror will only occur when it is lifted and put down. The shutter was closed before the mirror was put down. It can be seen that only the vibration generated when the reflector is lifted will cause the image to blur. Now let's assume that the vibration that can blur the image will last for 1/3 seconds, so if the duration of the whole exposure process is less than 1/3 seconds, we can think that the photo is completely generated by the vibration of the camera. In other words, its definition is 100% adversely affected by camera vibration. However, if the exposure time is 3 seconds, only1.11%of the photo clarity will be adversely affected by camera vibration. In this way, "as if" can cover the "bad image" and the clarity of the photo is obviously improved.

Of course, if the photographic light is strong enough to achieve "m greater than n" or even "m greater than 2N", it is obviously the most ideal. Only when the value of n is large and the light is insufficient, such as taking pictures indoors, in the forest or at dusk or dawn, can we consider reducing the shutter speed. If the aperture is f8 and the sensitivity is ISO200, then the shutter speed is only1/60s, and it is meaningless to try to improve the speed. Because whether you open the aperture or improve the sensitivity, the image quality will drop significantly. In this way, we reduce the aperture to f32, reduce the sensitivity to ISO 100, and add PL filter, the shutter speed can be reduced to 1.5 seconds.

Third, always beware of the influence of glare on image quality.

There may be nothing we can do about the dazzling light that is connected by colored spots of different sizes. Because that kind of glare is caused by the presence of particularly bright highlights in the picture. Such as the sun or street lamps. These things exist in the picture, and if they are blocked, they can't be photographed. Although high-grade lenses can avoid glare to a greater extent, sometimes such glare is quite beautiful. For another most common glare, we can reduce its influence on the picture in our own way.

In fact, glare is not only observed through lenses. We can observe with our own eyes: open a book and look at the sky with our left hand. We will find that the words on the book are not as clear as they usually look, as if there is a mist on them. This is dazzling light at work. Then use your right palm to block the sky as much as possible, and move in the direction of the book. Finally, let your palm be next to the upper edge of the book. In this process, we can see that the "mist" is getting thinner and thinner, and the text is getting clearer and clearer. The eye is like this, and so is the lens. And the hood on the lens just plays the role of the palm.

However, the hood is often not long enough for three reasons: first, the shielding range of the hood should take care of the wider end of the zoom lens; Second, it takes too long to carry or use; Third, in order to control the production cost. At this time, the advantages of SLR cameras are reflected. We can use light opaque objects such as hands, hats, notebooks and even reflectors to block the bright parts in front of the camera, but they are not in the picture. Then carefully observe the effect in the view frame, so as to control and adjust the direction and angle of occlusion. We didn't press the shutter until we thought all the scenes we saw were in the clearest (transparent) degree suitable for shooting. Especially in "slow photography" such as landscape photography, this method is quite practical.

Fourth, change the shooting distance appropriately to get better results.

This actually requires us to be good at taking photos with zoom lenses with different focal lengths, that is, there are two problems: on the one hand, the imaging quality of zoom lenses with different focal lengths is different. Generally speaking (especially the lens specially designed for digital cameras), when shooting with short focal length, the imaging is better. The main performance is high resolution, large contrast and high color saturation. When using the telephoto end of ordinary cheap lenses, the opposite situation often occurs: low resolution, insufficient contrast and dull color, which is what movie friends often call "meat". Therefore, we would rather use "foot zoom" and use the best focal length of the lens as much as possible to get a better image than blindly believe in the increasingly exaggerated "big zoom" on the lens.

On the other hand, because most cheap lenses have small apertures, it is difficult to blur the background (including the foreground). This is also an important reason why many movie friends spend a lot of money to buy large aperture lenses. But in fact, to blur the background, using large aperture is not the only solution. You know, blurring the background is to make the depth of field smaller. Depth of field is related to three factors: aperture, focal length and distance. The larger the aperture, the longer the focal length, the shorter the camera distance and the smaller the depth of field. Conversely, the greater the depth of field. So even if the aperture size can't meet our requirements, it's only less than one third. As long as the focal length and distance are well controlled, satisfactory background blur effect can be obtained.

When taking macro photos, I use the 70mm end of 18-70 mm lens, with a full aperture of f4.5 and the shortest distance of the lens of 0.38m When taking portraits, I use the focal length of 70-300mm lens above 150mm. As long as the shooting distance is not too far, even if the aperture receives f8, the background can still be "pasted".

It may be confusing to ask for "short" on the one hand and "long" on the other. But as long as you are good at analyzing and comparing, clarifying the main idea, accumulating experience and understanding the lens with your heart, beautiful photos will naturally come to you.