Find the exposure time and aperture parameters of various weather and time periods.

Photography cannot unilaterally force fixed values and parameters. The exposure time and aperture parameters of various weather and time periods are not fixed. Under the outdoor natural light condition, the exposure of negative film is related to weather, early, middle and late seasons and time, and illumination direction. The factor that determines the brightness of the scene is the reflective ability of the scene itself, such as snow. The beach is more reflective, while the brightness of forests and parks is darker. Then, the weather can be divided into: sunny, cloudy, cloudy or rainy; ? The time can be divided into: noon (10 ~ 14), 8 ~ 10 or afternoon 14 ~ 16, 2 hours after sunrise or 2 hours before sunset, half an hour after sunrise and sunset, and half an hour before sunrise and sunset; Between each of the above aspects (separated by commas), the brightness difference is about 2 times, which just corresponds to the first-class aperture or the first-class shutter. For example, sunny days are twice as bright as cloudy days and four times as bright as cloudy days. Give you an exposure reference value under the brightest conditions, that is, summer, noon, sunny days, taking pictures at the seaside in the sun. At this time, you can use the aperture F22 and the shutter1125 seconds. Then you can calculate the exposure under other lighting conditions. For example, in winter, at noon, on a cloudy day or in the sun, use F8, 1/60second (the combination of aperture and shutter is increased by 4 levels). With the above classification, it is easy to master photographic exposure. For example, at 8 ~ 10 in the morning in spring, the weather is fine, so you can take pictures in the park under the sun. If you use F 1 1, 1.25 seconds, then if it's after 16 in the spring afternoon, it's no problem if you still take pictures in the park in the sun. As long as a relative reference value is given, the exposure of all scenes under outdoor natural light can be easily calculated. Aperture (f) 45322216185.64 shutter (seconds)1/5001/2501125/.