Many friends who are new to photography will encounter blurred photos, especially at night or in a dark environment. This problem is particularly serious. What causes the photos to be unclear? What is the solution? Let Let’s discuss them one by one!


Formation of photos

First, let ’s revisit the most basic knowledge of photography. If you have read my previous article (refer to the formation of photos), you should know that the exposure of a photo mainly depends on 3 elements: Aperture, shutter (Shutter Speed) and film sensitivity (ISO). The combination of these three elements will constitute different exposures, and different settings should be used to achieve standard exposure in different environments.

What causes the photos to be blurred

The first reason is the focus error . If you use a large aperture to make the depth of field shallow, the blur is particularly obvious.

The second reason is that the shutter speed is too slow , this time I focus on this most prone situation.

A shutter is like a window. Its function is to control how much light enters the camera by opening and closing time. The longer the shutter is opened, the more light will enter accordingly, and the brighter the photo will be. The opening and closing time is the shutter speed. If shooting in a low-light environment, in order to make the correct exposure, the camera will extend the shutter open time to allow more light to be projected on the negative (or photosensitive element).

So why does this slow shutter speed affect the sharpness of the photo?

There are two main reasons for this:

  1. The photographer ’s own problem: Vibration will inevitably occur during handheld shooting. Even the most powerful photographers cannot guarantee that no hand shake will occur. Because of this natural human structure, the slower the shutter, the shaking motion The more serious
  2. The problem of the object being shot: The slower the shutter, the longer the exposure time. If the object is moving during this exposure process, the photo will leave “afterimage” and make the photo look Not clear enough. This is often encountered when shooting children or pets;


sb800 Option 1: Use the flash

Use flash to increase the amount and intensity of light. One of the simplest examples is the use of a flash. In the effective range of the flash, the light can illuminate the object sufficiently. Then the aperture does not have to be large, and the ISO value does not have to be high. It can keep the shutter speed at an appropriate value. . Of course, the application of the flash is a relatively advanced knowledge. I will discuss the use of beginners in a separate article.

t Option 2: Use a tripod

Avoid handheld shooting. Choosing a solid tripod will allow you to use slow shutter speeds while keeping your photos sharp.

200607192012 Option 3: Adjust the aperture and ISO value

If the reason for the blur is because the shutter is too slow, then we just need to increase the shutter speed! Remember the elements (aperture, shutter speed, and ISO) that make your photo properly exposed?

To increase the shutter speed and properly expose, then:

  • The aperture should be increased to allow more light to enter at the same time;
  • The sensitivity of the negative should be increased to make it easier for the negative to absorb light;
  • The above two situations occur simultaneously.

However, the size of the aperture is often limited by the lens itself, and the increase of the aperture will affect the depth of field (refer to the article on the relationship between aperture and depth of field). The higher the ISO value, the more serious the noise will be, making the photo not smooth. Therefore, the photographer should consider these elements together when adjusting.

How strong is the indoor light?

The human eye is a very precise and powerful organization, so for indoor lighting, such as incandescent lamps (light bulbs) and fluorescent lamps (light pipes), the human eyes will feel very bright, thinking that the light is sufficient, but in fact for The camera may not have enough light, so we ca n’t judge it with our eyes alone. We must use the camera ’s light meter to determine whether the shutter is too low and the photos are blurred.

Safety shutter

The name of the safety shutter may be relatively unfamiliar to beginners. In fact, it means “at a certain focal length, what shutter value will ensure that general hand shake does not affect photo exposure.” Its calculation method is very simple:

Safety shutter (s) = 1 / focal length (in mm)

For example, if you are using a focal length of 50mm, then 1 / 50th of a second is a safe shutter. At this shutter speed or above, general hand shake will not affect the exposure. For example, if you are using a 300mm long focal length lens, then your safety shutter It must be at least 1/300 second. Note that for normal people, the safety shutter should be no less than 1/30 second.

Help with anti-shock technology

The current anti-shake technology is very advanced (refer to the article Optical Image Stabilization vs Electronic Image Stabilization), which allows users to shoot at a speed 3-4 steps lower than the safety shutter. For novice photographers or seasoned photographers, it’s best to take this into consideration when buying a camera / lens!

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Author: Alex Tam