Understand the camera shutter angle

I encountered a problem after starting BMPCC. The positioning of BMPCC is a cinema camera. In terms of shutter parameters, the shutter angle is used. Accustomed to the shutter speed of SLR, it is not suitable for the shutter angle.

I looked up relevant information on the internet, and many people also have this question. Some people ask how to change the setting to the shutter speed, while others discuss the shutter conversion formula.

I looked up the related materials of movies and videos. It is found that the conversion of shutter angle into shutter speed is not worth the loss. Before explaining the reason, let's briefly understand the shutter and shutter angle.

Cameras and cameras can be simplified as pinhole imaging models. The closed carton has a small hole, and a cover (shutter) is stuck on the small hole. The size of the hole and the length of time the hole is opened determine how much light will enter the carton.

Because we are talking about the shutter here, let's assume that the aperture size remains the same. Then the longer the cover (shutter) is opened, the more light comes in.

The opening time of the cover (shutter) is the shutter speed.

If you have played with a camera, you should be familiar with the following shutter speeds:

1/ 1000 – 1/500 – 1/250 – 1/ 125 – 1/60 – 1/30 – 1/ 15 – 1/8 – / kloc-0//4 – 1/2 – 1 – 2 – 4 – 8 – 15 – 30

"The shutter will freeze instantly."

This sentence, "solidification" and "instant", are related to the movement of objects. A stone at rest doesn't need to solidify. No matter whether you shutter fast or slow, it is quietly waiting for you.

Suppose you shoot a car at a constant speed of 1m/s, if the shutter is1s. Then the second you open the shutter, the car has moved1m. The photo you take will be the image of the car's movement track.

If the shutter is set to110000 seconds. During that short time, the car hardly moved. Can shoot a clear and complete car (not including the imaging of motion trajectory)

When making a movie with film. 24 frames of film are taken every second, and the exposure of each film is 1/24 seconds without speeding up the door.

As shown in the figure. In the process of moving the film, a linkage device drives the blades of the rotating shutter to rotate together.

The blade rotates with each frame of film.

If the blade is opened 360 degrees (fully open), the film is not blocked, and the exposure time is still 1/24 seconds.

If the shutter blade is not fully opened, the blade opening angle is 180 degrees. Half the time, the film is blocked by the blade and cannot be exposed. Then the exposure time is halved, 1/48 seconds.

Many times, taking pictures requires stability, and the subject is required to be clear and solidified. On the other hand, movies require objects to have moving and dynamic effects.

If the opening angle of the blade is very small when shooting a movie, then all 24 movies are clear moments. Playing together is a feeling of jumping and stopping animation. When the shutter blade is opened at 180 degrees, the motion of the object is more consistent with people's consistent impression of the film at 1/48 seconds. Looks more natural.

There is no scene where the shutter speed is frequently switched.

Just fix the shutter angle at 180 degrees.

Aperture and shutter control the exposure of film.

In order to conform to the motion of the film, the shutter is limited.

In order to pursue profound effects, the aperture has little freedom.

What can be changed is the external light. Adding neodymium mirror reduces the overall light intensity. Expose and fill the light with various lighting equipment.

It is because of these challenges that film photography is more attractive.

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