How to use a long photographic lens?

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, and the shot image is larger than the standard lens at the same shooting distance, which is suitable for shooting the details of the distant scene and shooting the 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, this brings some difficulties to accurate focusing. 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. Long-distance shooting of scenic figures, tourism photography, portrait photography (when shooting standard photos, use a common telephoto lens of about 100mm to reduce image distortion, and use a lens of 105mm for the best effect), stand stage, sports game picture shooting, zoo animal shooting, wild animal shooting, auxiliary mirror close-up shooting, etc. It is ubiquitous in these numerous fields.

When shooting with a long focal length lens, fast photographic film and fast shutter are generally used. If shooting with a 200 mm long focal length lens, the shutter speed should be above 1/250 seconds to prevent camera shake and image blur when shooting with a hand-held camera. In general, in order to keep the camera stable, it is best to fix the camera on a tripod. Without a fixed tripod, you can take several postures as shown in figure 1-2.

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. It is best to use a film faster than ISO 400/27 degrees to ensure sufficient shutter speed.