How to calculate the exposure time of long exposure photos

Calculate the time interval from shutter opening to closing.

Exposure time mainly refers to the exposure time of the film. The longer the exposure time, the brighter the photo produced on the film, and vice versa. When the outside light is relatively dark, it is generally required to extend the exposure time (such as night scenes).

The faster the shutter speed, the easier it is to capture moving objects and make them clearer images. When the shutter speed is lower than 60th of a second, it is best to use a tripod, otherwise the image will be difficult to clear.

Extended information:

There are three factors that can affect whether a picture is correctly exposed: aperture, shutter speed, and ISO (sensitivity). Aperture and speed jointly determine the amount of light entering, and ISO determines the photosensitive speed of ISOCCD/CMOS.

If the amount of light entering is not enough, we can open a wider aperture or slow down the shutter speed. If it is still not enough, we can increase the sensitivity (ISO). The disadvantage of a large aperture is that the resolution is not as good as a medium aperture. When the shutter speed is reduced, the picture may be blurred. When the ISO is increased, the picture quality will also decrease.

Important conclusion: A correctly exposed picture can have N different combinations of aperture and shutter speed.

Baidu Encyclopedia-Exposure Time