What Is ISO and How Do You Use It?

In every setting, a photographer has to take into consideration the amount of light they have to work with.

Thanks to flash photography, dim lit settings can easily be managed, but what if you do not want to work with a flash? What then? This is when adjusting ISO can assist in capturing the image you need.

ISO is the level of sensitivity a camera is to light. This is measured on the image sensor, which is a component that gathers light and transforms it into an image.

If the image sensor has a greater sensitivity to light, more details are captured.

Therefore, adjusting ISO helps a photographer in less than ideal conditions. The idea is to increase the level of sensitivity in low light settings and decrease when there is plenty of light available.

How to control ISO.

Every Digital SLR comes with a base ISO. This is the lowest ISO number with the least sensitivity to light. Most cameras start at 100 or 200. From there, the numbers increase by powers of two. Respectively, they are as follows: 100, 200, 400, 800, 1600, 3200 and 6400.

With every jump in the number, the level of sensitivity doubles. For example, an ISO of 400 will mean the image sensor is twice as sensitive to light compared to an ISO of 200.

Since ISO controls light sensitivity, it can be useful when adjusting shutter speed. Working together, you can improve any action shot. If you are in need of a faster shutter speed and know you will lose light as a result, you can increase the ISO number to compensate for exposure.

The only problem with increasing ISO is the loss of image quality. As the ISO number increases and the image sensor becomes more sensitive to light, there is also an introduction to noise.

This can be frustrating for most photographers as they pine for sharper pictures by increasing shutter speed, but lose image quality due to a higher ISO.

Not many photographers lug around a tri-pod and therefore, it is beneficial to know what shutter speed works best for hand held photography. Every photographer is different; some are shakier than others. This is why it is important to experiment and learn for yourself.

ISO Photography Project!

In shutter priority mode, go outside and take several pictures of the same scene, each with different shutter speeds. Afterward, take a look at your pictures and figure out which one is the sharpest image, this will be the shutter speed you work best in with ideal conditions.

Of course, shutter speed will always have to be adjusted depending on the amount of motion in a scene.

Once you have shutter speed under control, adjust your ISO setting. With the same shutter speed, try out different ISO numbers and do the same as above.

Look through them and assess which ISO number works best with that shutter speed.

Every situation will be different, but once you are familiar with playing with ISO and shutter speed together, your pictures will improve. However, if there is plenty of light and lack of action in a scene, it is always best to simply keep your ISO at the lowest possible number to retain quality.

ISO, Shutter Speed & Aperture.

Photo by Aramgutang: https://en.wikipedia.org/wiki/User:Aramgutang

Knowing how ISO, shutter speed and aperture work separately, it is beneficial to learn how to use them together. Especially when a photographer is in manual mode, it is important for them to understand how changing one will require changing the other two.

These three aspects make up the Exposure Triangle, which means, you cannot use one without affecting the other.

In order to understand how they correlate, it is best to imagine how the camera works. When the shutter release button is pressed, the subject being captured is passed through the lens in the form of light.

The first component at work is aperture. This hole at the end of the lens tunnel can either be small in diameter to allow little light to pass through or large for an ample amount of light.

Behind aperture is the shutter acting as a gate for the passage of light.

Depending on the speed, the shutter will open and close. In this short amount of time the shutter is open, light is collected on the image sensor. Once the shutter is closed, no more light will be allowed through. The image sensor will then use the collected data, generate an electric signal and create a digital image. ISO controls the image sensor’s sensitivity to light.

Now that you know how the process works, you can learn how to play with the three together to help you achieve the exact exposure you would like for an image.

The best way to figure out how to adjust all three at once in manual mode is to focus on changing one first and thinking of the consequences that will result if the other two remains unchanged.

Starting at the beginning of the process, and adjust aperture first. Look at the scene you are trying to capture.Is it a landscape where you would like every detail to be in focus?

Or is it a portrait where you would like only the subject in focus with the background blurred? If it is the first scenario, you will require a small aperture. Make the adjustment, by setting your aperture to a high f-stop number.

A small aperture means a small hole and a small hole means very little light will be allowed through.

The shutter must compensate for this lack of light by staying open longer. Therefore, a small aperture is best suited for a slow shutter speed.

On the other hand, a larger aperture can be managed effectively with a fast shutter speed. Since the hole is large and allows plenty of light passage, the shutter does not have to be open as long.

In lighting conditions where there is a significant amount of light available, you do not have to worry much about adjusting ISO. Remember, the higher the ISO number, the noisier an image will appear.

That is why it is best to keep ISO low in most situations.

ISO comes into play more so in dim lighting situations. Maybe you need a fast shutter speed in a low light situation. Increasing the ISO sensitivity means less time the image sensor needs to be exposed to light. In other words, the shutter does not need to be open for long.

Adjusting the ISO should always be a last resort to improve an image. But a grainy image is better than a blurry one, so there are times when changing the ISO is absolutely necessary.

Manually controlling the three contributing components to exposure can be a challenge. Once all three are mastered in synchronization, you can improve your photography immensely.

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