Basic concepts of photography (understanding aperture, exposure time and iso sensitivity)

Aperture is a device used to control the amount of light entering the photosensitive surface of the fuselage through the lens. Usually in the camera. In order to express the pore size, we use F/ value.

Large aperture, small aperture

-The larger the aperture (the wider the aperture, the lower the value under f, because the value is on the molecule, the smaller the molecule, the larger the whole), the more light enters, and the shallower the depth of field (the more blurred the background, which is suitable for shooting people).

-The smaller the aperture (narrow, that is, the higher the lower limit of f), the smaller the amount of light entering and the deeper the depth of field (clear distance).

Exposure time is the time when the shutter is opened in order to project light onto the photosensitive surface of photographic photosensitive materials. It depends on the sensitivity of photographic photosensitive materials and the illumination on the photosensitive surface. If the exposure time is long, there will be more light, which is suitable for poor light. Short exposure time is suitable for good light.

The longer the exposure time, the brighter and darker the photos generated on the negative.

In the case of dark outside light, it is generally required to extend the exposure time (such as night scene).

The faster the shutter speed, the more you can catch the moving object and make it clearly imaged. When the shutter speed is less than one sixtieth of a second, it is best to use a tripod, otherwise the image will be difficult to be clear.

1 ",0" 6, 1/80, 1/2000 and so on to indicate the exposure time. From left to right, the exposure time is getting shorter and shorter.

Sensitivity, also known as ISO value, is a measure of the sensitivity of negative film to light, which is determined by the measurement of sensitivity and several values, and has recently been standardized by the International Organization for Standardization. For the negative with low sensitivity, it takes a long exposure time to achieve the same imaging effect as the negative with high sensitivity, so it is usually called slow negative. Highly sensitive negatives are therefore called fast negatives. Whether it is digital or negative photography, in order to reduce exposure time, relatively high sensitivity usually leads to image quality degradation (due to coarse negative particles or high image noise or other factors)

Higher sensitivity can get faster shutter speed, and higher ISO value can provide faster shutter speed in the same light source environment, which can effectively avoid hand shock.

High-sensitivity image quality is noisy.

The lower the sensitivity, the better the imaging quality.

Slow shutter

low noise