What is the difference between HD cameras and SD cameras?

The difference between high-definition cameras and standard-definition cameras:

Standard-definition: DVD quality. Generally, it is 720*576 or 640*4804 (4:3) or 848*640 (16:9). Anything close to the value is also considered standard definition. ?

HD: 1280*720I (i stands for interlaced, p stands for progressive). The same below (16:9) Full HD: 1920*1080I and 1920*1080p, 16:9. 1440*1080 is 4:3;

Lens classification:?

Long focal length lenses refer to lenses with a field of view less than 40° and a focal length greater than 25mm: for cameras A zoom lens refers to a lens whose focal length is adjusted to greater than 25 mm.

For example, when the focal length value is 50 mm, 75 mm, 100 mm, 150 mm, etc. Long focal length lenses are also called telephoto lenses, telephoto lenses, narrow-angle lenses, etc. ?

Wide-angle lens is also called short focal length lens: it is a lens with a focal length shorter than a standard lens and a field of view greater than 60°. For the zoom lens on the camera, it is the lens with a focal length less than 25mm. For example, the focal length is 16mm, 12mm, 10mm, etc. ?

A zoom lens is a lens that can continuously change the focal length compared to a fixed focus lens. It is composed of multiple groups of positive and negative lenses. In addition to the fixed lens group, there is also a movable lens group. Through the zoom ring of the lens barrel, the movable lens group can be moved to change the distance between the objective lenses and the lens can be continuously changed. focal length.

The concept of wide angle:

A wide-angle lens is a lens with a shorter focal length and a larger angle of view. The purpose of using a wide-angle lens is to achieve a wider field of view and magnificent artistic effects. For consumer-grade DC? The so-called wide-angle is actually the ability to shoot with an 8mm focal length.

It should be said that 18-35mm is a short-focus lens: also called a wide-angle lens. Lenses below 18mm are called ultra-wide-angle lenses or fisheye lenses.

Advantages of wide-angle lenses:

The basic characteristics of wide-angle lenses are: large angle of view and wide field of view. The scope of the scenery observed from a certain viewpoint is much larger than what the human eye can see at the same viewpoint. It has a long depth of field and can show a considerable range of clarity. It can emphasize the perspective effect of the picture and is good at exaggerating the foreground and expressing the scenery. A sense of distance, which helps enhance the appeal of the picture. ?

The viewing angle range is large and can cover a wide range of scenery. The so-called wide range of viewing angles: that is, at the same point of view, the distance to the subject remains the same and the shooting lens is used with three different focal lengths: wide-angle, standard and telephoto. The result is that the former captures more up, down, left, and right shots than the latter. Scenery. When a photographer has no way out, if it is difficult to completely capture a scene with a 50mm standard lens, such as a group photo of people, etc., the wide-angle lens can easily solve the problem by taking advantage of the wide viewing angle. Another example is shooting vast fields or tall buildings in cities; using a standard lens may only capture part of the scene, and cannot show the width or height of the scene. Shooting with a wide-angle lens can effectively show the openness of a large scene or the majesty of a building towering into the clouds. ?

Short focal length: long depth of field. When shooting broad scenes, photographers generally rely on the characteristics of wide-angle lenses with short focal lengths to express the scenery with long depth of field: the entire scenery from near to far is included in the range of clear expression. In addition, when shooting with a wide-angle lens, if a smaller aperture is used at the same time, the depth of field of the scene will become longer. For example: the photographer uses a 28mm wide-angle lens to shoot, focuses on a subject about 3 meters away, and adjusts the aperture to F8, then almost everything from 1 meter to infinity enters the depth of field range. It is precisely because of this long depth of field that photographers often use wide-angle lenses as a highly maneuverable quick-shot lens. In some situations, photographers operate the wide-angle lens without having to focus on the subject. By focusing on the subject, you can complete the capture extremely quickly. ?

Can emphasize the foreground and highlight the contrast between near and far. This is another important feature of wide-angle lenses. The so-called emphasizing the foreground and highlighting the contrast between far and near means that the wide-angle lens can emphasize the contrast between near and far more than other lenses. That is to say: in photos taken with a wide-angle lens, close things are larger and far things are smaller, which makes people feel that the distance is widened and creates a strong perspective effect in the depth direction. Especially when shooting with an ultra-wide-angle lens with a very short focal length, the effect of near and far is particularly significant. ?

Can be exaggerated and deformed. Generally speaking, it is a taboo when using a wide-angle lens that the subject is exaggerated and deformed. In fact, it is not necessarily undesirable for the subject to be appropriately exaggerated and deformed. Experienced photographers often use wide-angle lenses to appropriately deform the subject by adding content, and take pictures of some very inconspicuous and invisible scenes that are unusual. Of course, when using a wide-angle lens for exaggerated and deformed expressions: first, it must be based on the needs of the subject matter, and second, it must be less but more precise.

Regardless of whether the subject matter requires it or not, it is not advisable to abuse the exaggerated and deformed expression techniques of wide-angle lenses; it is not advisable to blindly pursue grotesque and bizarre effects in form;