What is the obvious difference between telephoto and short focus in SLR?

Telefocus means that the lens can be extended to a relatively long distance. For example, 10 times means that the lens of 35 mm is extended to 350 mm, which is convenient for capturing distant scenery and creating a large scene even if it is far away from the object. A long focal length lens refers to a photographic lens whose focal length is longer than that of a standard lens. Telefocal lenses are divided into ordinary telephoto lenses and ultra-telephoto lenses. The focal length of ordinary telephoto lens is close to that of standard lens, while the focal length of ultra telephoto lens is much larger than that of standard lens. Take 135 camera as an example, the photographic lens with a focal length of 85 mm-300 mm is a normal telephoto lens, and the lens with a focal length of more than 300 mm is a super telephoto lens.

According to the structure of optical group, telephoto lens can be divided into ordinary telephoto lens, inverted telephoto lens and reflective telephoto lens.

Shooting with a long focal length lens has the following characteristics:

First, the angle of view is small. Therefore, the spatial range of the shooting scene is also small. At the same shooting distance, the shot image is larger than the standard lens, which is suitable for shooting the details of distant scenes and shooting subjects that are not easy to get close to.

Second, the depth of field is short. So you can highlight the subject in a messy environment. However, it brings some difficulties to accurate focus adjustment. If the focus is slightly inaccurate when shooting, the subject will be blurred.

Third, the perspective effect is poor. This kind of lens has obvious characteristics of compressing spatial depth and exaggerating background.

When using a long focal length lens, it is usually used to shoot distant scenes. Due to the absorption of air and the influence of diffused light. Therefore, it is not easy to achieve very accurate focusing because of the small contrast of the captured image and the serious extinction of dust particles. When shooting with a telephoto lens above 300 mm, it is still difficult to gather all colors of light at one point, resulting in sub-spectral problems. Based on the above situation, sometimes the image quality of the shot works is not high.

Although the use of long focal length lens is influenced by many factors, its advantages are the main ones. Take long-distance photos of scenic figures, travel photos and portraits (when taking standard photos for affixing certificates, use a common telephoto lens of about 100mm to reduce image distortion, and use a lens of 105mm for the best effect), take photos of stands and sports competitions, take photos of zoo animals, take photos of wild animals, and take close-up photos with auxiliary mirrors.

When shooting with a long focal length lens, fast photographic film and fast shutter are generally used. If shooting with a 200m long focal length lens, the shutter speed should be above 1/250 seconds to prevent camera shake when shooting with a hand-held camera. Generally speaking, in order to keep the camera stable, it is best to fix the camera on a tripod.

Generally, the telephoto lens is only used in special circumstances, and the camera cannot be fixed with an ordinary tripod, otherwise the overweight lens will damage the camera base fixed on the tripod. Therefore, it is necessary to use a tripod that can support the lens holder to fix the camera. When there is no such special tripod, it can be fixed with two legs, one leg to fix the camera body and the other leg to support the telephoto lens. The telephoto lens generally has a field of view of 18~ 10 and a focal length of 135~250, which is suitable for shooting landscapes, portraits, sports, stages, news, ecology, architecture, documentary folklore and so on.

Short focus generally refers to near focus, or macro, that is, it can capture scenes close to the lens, which is generally used to shoot words in books. A photographic lens with a shorter focal length than a standard photographic lens and a longer focal length than a fisheye lens is called a short focal length photographic lens. Short-focus lenses are usually divided into two types: ① ordinary wide-angle photographic lenses (the focal length is close to the standard lens); ② Super wide-angle photographic lens (focal length close to fisheye lens).

1. The short-focus lens has a large viewing angle and is suitable for shooting in a narrow space. It can make a narrow space wider, but short-focus lenses, especially ultra-short-focus lenses, will bring the effect of spatial perspective distortion, which will make objects close to the lens look particularly large, while objects far away from the lens look particularly small. Therefore, when using the short-focus lens, we should be very careful when dealing with the close-range lens. If we don't grasp it well, it will easily lead to the unobvious performance of the main body.

2. A short-focus lens will distort a straight line and make it bend. Therefore, in some shooting subjects with high requirements for straight lines, such as architectural photography and remake, it should be used with caution.

3. Unless the shooting distance is very close, it is impossible to get a picture with a small depth of field with a short lens, which always produces a large depth of field.

4. When using a short-focus lens, be sure to focus carefully. Because of the large depth of field produced by the short-focus lens, photographers often feel that the image on the whole framing picture is very clear, but it is not accurately focused on the subject. After the film is enlarged at high magnification, the main body will still appear virtual paste.

5. Due to the large viewing angle of the short-focus lens, the correction of the metering value should be considered when TTL metering, especially when the brightness of the background and the subject is quite different, otherwise direct exposure according to the metering value will cause serious exposure errors.