Shutter Speed Controls: Ambient Light or Flash Light?

04 FEB, 2020 | BY YU CHENHAO

A photograph's exposure determines how light or dark an image will appear when it's been captured by your camera. As we all know, it is determined by the classical exposure triangle: Aperture, ISO and shutter speed. However, it may still be a difficult issue for some beginners to accurately apply them to achieve the light they want, for example, a proper exposure of portrait when using speedlite or flash in the studio.

 

Shutter speed plays a significant role in perfecting the effect of an image. By working together with Aperture and ISO, the classical exposure triangle creates a well-exposed photo. However, each of them has their own responsibilities, and this article will explain this issue from the perspective of shutter speed. Why shutter speed controls ambient exposure but not flash exposure? What’s the difference?

Before we explore the secret of shutter speed, let’s figure out the definitions first.

What Is Shutter Speed?

There is a small component called the shutter beside the sensor of your DSLR camera. When you take a photo, this part opens  to let light reach the sensor, resulting in your image. Shutter speed describes the speed that a shutter opens and closes. In other words, shutter speed is the length of time when the sensor is exposed to light. The amount of light that reaches the image sensor is proportional to the exposure time.

A high shutter speed means that the shutter opens for a short time. A low shutter speed means the shutter opens for longer. For example, a shutter speed of 1/200 means 1/200 of a second.

Shutter Speed Controls Ambient Exposure

 When we shooting indoors with flash as the main light source, we may find it is difficult to balance the light to your subject and the light to the background. In most of time our goal is just creating enough light to illuminate the subject, while the background can be damned. As a matter of fact, however,  we may get a photo with a bright subject and a very dark background with a common shutter speed( about 1/200 or 1/250 of a second).

What you need to do is to make use of ambient light in your space or studio, adjusting the settings in your camera can help allow that ambient light into your exposure and create more depth in the photo.

To allow more ambient light in, you need to make the shutter speed a little slow. This needs constant adjusting for a beginner, and you can try manual mode, which will allow you to adjust your shutter speed to do this. Also, you should set a wide aperture, to allow enough light get into the sensor.

 Please Note: Shutter Does Not Control Flash Exposure

 As long as you are shooting at or slower than the flash sync speed for your camera, then shutter speed has no control over the amount of flash getting into your digital sensor. If you shoot faster than your flash sync speed, you are only reducing the portion of the sensor that is exposed, but not reducing the amount of flash reaching the sensor.

Summary

A clear understanding of the definition of shutter speed and the difference between the flash light and ambient light will be very helpful when you intend to create the effect you want for portraits in your studio.

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