I don’t know if you guys know how a photo is formed? In fact, a photo is “let the film blare and record the light at that moment”, so some people say that photography is “capturing light and shadow.” So for a beginner in photography, what must be known? The answer is the exposure iron triangle: film speed (ISO), aperture and shutter speed.

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ISO

Before digital cameras became popular, photographers used film, and film usually had a value such as ISO50/ISO200/ISO1600, etc. In fact, this number represents the sensitivity of the film. The higher the value, The stronger the ability to absorb light, the more suitable it is to shoot in a dark environment but no matter how strong the light-sensitivity is, you can’t shoot in a “completely no light” environment! So when should you use a photosensitive film. Why is the ISO set in a digital camera? In fact, under normal circumstances, the higher the ISO the stronger the light sensitivity, the stronger the signal noise, which is in the darker areas of the photo the more obvious.Photos of ISO 80 are the most detailed and smooth, while the photos of ISO 3200 are full of noise, so the higher the ISO value, the better. And when to use which value of ISO, we still wait for the reader to understand the following aperture and shutter speed before explaining.

Aperture

I believe everyone knows what the “lens” looks like? In fact, the “aperture” is “a window hidden in the lens”. Just imagine that the sun is very fierce, and the size of the window can control how much light enters the house, and the “aperture” It is the same principle, used to control how much light enters the camera and shines on the film.

Shutter Speed

The shutter speed is the time to open the “aperture” window. The longer the time, the more light can enter; on the contrary, the shorter the time, the less light can enter. We can also imagine a water pipe. The longer the tap is opened, the more water will flow out.

Conclusion

So how can the film speed (ISO), aperture and shutter speed affect each other? Let’s take a look at an example: For example, if you want to record 10 units of light, then you can use the following method:

1. With a sensitivity of 1 unit per sec and aperture of 1 unit, let the shutter open for 10 seconds (1 x 1 x 10 = 10)
2. With a sensitivity of 2 units per sec and aperture of 2 units, let the shutter open for 2.5 seconds (2 x 2 x 2.5 = 10)
3. With a sensitivity of 100 units per sec and aperture of 1 unit, let the shutter open for 0.1 second (100 x 1 x 0.1 = 10)

It can be seen from the above that there can be many combinations to absorb 10 units of light, and we have to make different judgments according to different situations. Remember the choice of ISO value before? After reading this example, you should know that the signal noise of example 1 is much less than that of 3, but example 3 is suitable for use in a dark environment because it can be used in a short period of time to absorb more light.

Written by Collin Smith @ remotes.works Holborn London