Really ask me how to learn photography? (beginner's chapter)

Before we begin, let me explain that my tutorial is mainly about digital cameras. On the one hand, most friends now have digital cameras, and few of them play with film as soon as they get started. On the other hand, I know only a little about digital cameras. But some basic principles of photography think that digital and film are the same. In addition, the positioning of this tutorial is an introductory tutorial, which may be too simple for some friends. Friends who have a certain foundation can give me a reply from the standpoint of helping me find mistakes and help me improve this tutorial.

Where to start? Let's use the aperture and shutter. The easiest to understand but also the most difficult to master. The aperture can be imagined as a hole in the camera lens. The opening of this hole is a large aperture and the contraction is a small aperture, but the nominal value of the aperture is opposite to its size. For example, F2.8 is larger than F4. The larger the aperture (that is, the larger the hole), the more light will pass through at the same time. Then how much light the camera receives should depend on the aperture size and time. This length of time is the shutter. Modern cameras can measure light automatically. They decide how much light they need to receive according to the intensity of the spotlight, and then deduce the size of the aperture and the speed of the shutter from this light. Mathematically speaking, I can obviously get many combinations from one product, and I can narrow the aperture, and I can get the same light just by slowing down the shutter. So do the aperture and shutter have other functions besides adjusting the intensity of light? How can I adjust these two values?

I think the aperture has two functions besides dimming. One is to control the depth of field and the other is to control the image quality. Everyone knows that a camera needs to focus, which is the same as the human eye. Everything in front of you can't be clear, and the depth of field is a clear range. A large depth of field means a wide range of clarity, and vice versa. For example, everything from me 10 meter to 12 meter is very clear, and the depth of field is 2 meters. The range of10m to 20m is very clear, and the depth of field of10m is larger than the previous 2m. After understanding the depth of field, let's talk about the relationship between aperture and depth of field. Large aperture, small depth of field, small aperture, large depth of field. As for why, you can refer to the small hole imaging in junior high school physics, draw a big hole and a small hole, and draw the incident angle of light. I'm really too lazy to draw. Another function of aperture to control image quality is not the real function of aperture. Mainly the level of optical lens is still limited, so some low-priced lenses are prone to poor image quality in large aperture and good image quality in small aperture. It is generally believed that the aperture F8 is the best aperture, and the image quality is not the best if it is too large or too small. Therefore, if there is no special requirement for depth of field, especially when taking landscape photos, it is a common method to narrow the aperture.

For most people, shutter is easier to understand than aperture. When shooting a moving figure, a faster shutter can freeze him, and a slower shutter may be empty. In addition, if the shutter is too slow, the photos taken are likely to be burnt by the vibration of the hand holding the camera. The longer the focal length, the easier it is to paste. Because the telephoto segment is equivalent to amplifying the vibration of the handle. It is generally believed that the safety shutter should be the reciprocal of the focal length, such as the focal length of 28mm, and the shutter should be above 1/28 to ensure non-pasting. Of course, this is also related to personal determination. I am basically safe at the 28mm end of110. I also took a hand-held photo of 1 sec at the fixture. According to the relationship between aperture, shutter and light just now, if the light is certain, if you want to improve the shutter, you have to increase the aperture. But unfortunately, the aperture is not as big as you want. Generally speaking, the maximum aperture of consumer-grade DC is F2.8, and the lens of DSLR (Digital SLR) is around 4,500 yuan. The maximum aperture of many low-priced lenses is only F3.5 or even F4. So sometimes a lens with a large aperture is called a fast lens because it can provide a higher shutter. Isn't there any other way to raise the shutter? Yes, that's ISO (high sensitivity)

What we just said is that the aperture and shutter determine the light. However, we also have a trick to amplify the light to get the required exposure. In the film age, ISO was improved by controlling the chemical properties of silver salt, such as leaving a lot of silver salt particles on the film with little light to make the photos look bright. In the digital age, film is replaced by electronic photosensitive elements, so we can get the same bright photos with little light as long as we amplify the electrical signals. So usually in places with poor light, we can get a faster shutter by improving ISO. But ISO is not a free lunch. Excessive promotion of ISO photos will lead to many manic points. If you spend DC, you'd better give it up. The photos on ISO200 will be terrible. Relatively speaking, DSLR is much better, especially Canon's DSLR and ISO 1600 can take quite detailed photos. So why is there such a gap between the two? Let's discuss the electronic photosensitive element, the core of digital camera.

Electronic photosensitive elements are used to replace traditional films. When the light shines on the photosensitive element, he converts the light into an electrical signal and then generates a picture. The problem lies in the size of this photosensitive element. The film size of the camera we usually use is fixed, with a width of 35mm, which is the so-called 135 camera. However, the price of electronic photosensitive elements is relatively expensive, so in digital cameras, the commonly used photosensitive elements are far from so large. When the area is small, the distance between photosensitive elements is also small, and electronic elements interfere with each other, which is easy to produce mania. Relatively speaking, the photosensitive element of DSLR is relatively large. The width of my O-record E-300 is half of 35mm, 17.5mm, the photosensitive element of Nikon APS interface is 2/3 of 35mm, Canon's universal DSLR is11,and some of their full products are 1: 1. My E300 photosensitive element is relatively small, so it is also known for its high ISO. Generally, I can only use ISO400, and the impatience on ISO800 is very severe. However, besides size, other factors are also important. For example, Canon's is smaller than Nikon's, but Canon's high sensitivity control is excellent.

The size of the photosensitive element not only affects the high sensitivity, but also has a great influence on the drawing angle. As you can imagine, light comes from the same illumination angle. If the photosensitive element is half smaller, it means that only half of the image is converted into an image by photosensitive. Essentially equal to increasing the focal length. So for my camera, the focal length of the lens of 14-45 installed on my machine should be multiplied by 2 to become 28-90, which is commonly known as the focal length after 35mm conversion. Simply put, the width of the photosensitive element is 1, which is a fraction of that of ordinary film, and the focal length should be enlarged several times.

Suddenly I found that I forgot to introduce what DSLR is. His full name is digital single-lens reflex camera. Generally speaking, this kind of camera can't take pictures with LCD (Olympus has recently made one that can). Only through the optical viewfinder. The light shines directly from the lens and shines on the viewfinder through reflection, that is, what you see is the scene coming from the lens. Generally, the lens of this camera can be changed, but as mentioned above, the actual focal length you get should be multiplied by the factor on the focal length marked by the lens.

Let's first introduce the lens, which can be divided into zoom lens and fixed focus from the point of view of zooming without zooming. Friends who use consumer DC may say fixed focus? Isn't it the kind that can't zoom? Who can use that stupid camera? My camera has a triple zoom. But not in the DSLR world. Because of the optical principle, the zoom lens always has certain limitations that affect its imaging quality, but the fixed focus is different. He has few restrictions and can give full play to its image quality. So people who pay attention to image quality like to use fixed focus. Although there are some restrictions on composition, its picture quality is definitely better than zoom. My only bull's head (that is, a good head) and my favorite 50 mm/F2 (converted from 35 mm to 100mm) are fixed focus heads. And the fixed-focus lens can easily enlarge the aperture. F 1 point, 2.0 fixed focus is everywhere. It can not only get a faster shutter, but also get a good depth of field, which is a sharp weapon for shooting people. The zoom lens needs no explanation. One thing, however, is that some low-priced zoom lenses have different maximum apertures in each focal segment. For example, my lens (that is, the lens I bought with the machine) is 14-45/3.5-4.5, and the end of 14mm can reach F3.5, and the end of 45 mm is only 4.5.

In addition, from the focal length, the lens can be divided into wide-angle and telephoto lenses. Generally, a wide-angle lens can be calculated by converting 35mm into less than 35 mm. Wide-angle lens can shoot large angles because of its wide painting angle, and is generally used to shoot landscapes or some environmental portraits. The medium focus lens is usually used to shoot close-up portraits because it can get a suitable depth of field without wide-angle distortion. Telephoto can shoot distant scenery or animals. In addition, there is a macro lens, which can enlarge and shoot very small objects and obtain a special effect.

There are many kinds of lens bayonet, and the lenses of all kinds of bayonet cannot be used universally unless an adapter ring is used. I am familiar with Olympus' 4/3 excuse, Nikon's interface, Canon's EF and EF-S interface. Generally, the lenses are original lenses made by manufacturers leaving the fuselage, and there are some third-party manufacturers such as Sigma, Tonika and Talmon. Each manufacturer has its own cow head marking method. For example, there is a red circle in front of Canon's bull's head, which is generally called red circle head or L head. Nikon's good head has a gold circle, and Olympus's good head also has a gold circle. However, generally speaking, there are at least 5600 lenses with rings. For me, only a drooling copy is really unavailable.