Hopefully, you will have seen the article on the exposure triangle. In the article, we take a brief look at Shutter speed, ISO and Aperture. In this article, we drill down a little more on shutter speed and how it affects the images you produce.

Look at the 2 images on the left.

Both are the same image, taken moments apart, but the one on the far left is using a fast shutter speed, and the one on the right of it is much slower, introducing blurring of the moving elements of the image. (the other parts of the exposure triangle were adjusted to ensure the exposure remained as consistent as possible).

These images highlight a creative example of when your choice affects the outcome. However, there will be times when shutter speeds show no real affect on an image, such as a still object (like in product photography).

In a nutshell, it is the time that the camera shutter is open. The typical range of speeds you will find on your camera go from the fastest (e.g. 1/4000 of a second) to the slowest (usually 30 seconds).

Many cameras also have what’s known as a ‘bulb’ mode, which allows you to leave the shutter open as long as you need it. This is best used with a remote shutter release and tripod to minimise camera shake.

So what speed should i be using?

The shutter speed you need depends on several factors, these include the amount of light available, how the ISO and aperture is set, and the effect you want to create. It is said that your ‘average’ user, taking the ‘average’ photos, will use something like 1/60th second most of the time, whilst that may be true, it’s probably not the correct speed a lot of the time. Lets look at a quick guideline -

For the average person to sucessfully take a sharp image (sharp meaning no visible blur due to camera shake), then the shutter speed should be roughly equal to the focal length of the lens. for instance, if you shoot an image with a 50mm lens, you should use around 1/50th sec or more.

This however, doesn’t take into account the crop factor of sensor sizes (don’t worry too much about this right now, we will get to that soon!) basically, the sensor in most modern dSLR cameras is smaller than the 35mm frame of a film camera (or the sensor in ‘full frame’ digital cameras), so the maths have to be modified slightly – thus your shutter speed should be roughly 1.6 x the focal length as the sensor is 1.6x smaller than full frame. for example, with a 50mm lens, your shutter speed should be around 1/80th sec.

There are also other sensor sizes around, including 1.3x to confuse things even more, refer to your camera manual to determine the size of your sensor.

Be aware, that although the guidline above is a good starting point, it is only a guideline, and other factors affect choice, image stabilisation and even your hand holding technique all come into the mix. Thankfully, shutter speed choice is one of those things in photography that becomes second nature with a little practice and understanding.

When thinking about and altering shutter speed, always remember the other 2 parts of the triangle and the relationship as you will need to alter either one or both of the other 2 to maintain the exposure you’re trying to achieve (notice i said the exposure you’re trying to achieve, as there is always one technically correct exposure, but as multitude of creatively correct exposures.

as an example, if the exposure you want has a shutter speed of 1/125th sec, but you decide you need to speed it up by 1 stop to 1/250th, perhaps to compensate for motion blur, or freeze action, then either the aperture, the ISO or both will need to be raised by a total 1 stop. this is because raising shutter speed by 1 stop effectively lets in half the amount of light, so you need to get that back in another way.

What’s a stop?

Stops are the mathematical term for the differences in shutter speed, ISO and aperture. a quick example is that the size of a lens aperture is measured in F-stop. f1.4, f2.8 and so on. you can read a full explanation here.

Related posts:

1. Exposure triangle
2. Aperture – Get creative
3. Camera icons explained