How does selecting ISO on a camera improve photo quality? This article will teach you how to set the ISO value on your camera to take the best photos.
ISO is one of the basic camera settings, including on smartphones. For professional photographers, it is one of the main ways to control the quality of the images they take. Amateurs often ignore them, which is a mistake, because knowing when to use which settings can make shooting much easier and significantly improve quality. How does ISO affect your photos, and how do you use it correctly?
What is ISO in a camera?
ISO is one of the camera settings that determines the brightness of a photo.
Two other settings that affect brightness are aperture and shutter speed. In a digital camera, ISO mimics the sensitivity of film. As you increase the ISO value, your photos will become brighter. This way, ISO can help you take pictures in the dark or when you're shooting fast-moving subjects.
But increasing ISO has consequences. A photo taken with too high an ISO setting will contain a lot of graininess, known as noise. In extreme cases, it may be unusable. Therefore, increasing the brightness of a photo with ISO is always a compromise.
You should only increase the ISO if you cannot make the photo brighter by increasing the shutter speed or aperture. For example, using a longer shutter speed will result in a blurry image.
Of course, you can also try brightening your photos later when editing them on your computer. One way that photo editing software makes photos brighter is by artificially increasing the ISO. However, increasing the ISO on your camera almost always results in better image quality than increasing the brightness on your computer.
What does ISO mean in a camera?
The acronym ISO stands for International Organisation for Standardisation. It is responsible for creating industry standards, including those related to the photography industry.
In 1974, two film sensitivity standards, known as ASA and DIN, were combined into a single ISO standard, which now defines sensitivity. In traditional (film) photography, ISO (or ASA) indicates how sensitive the film is to light.
The light sensitivity values are always indicated on the film packaging: 100, 200, 800, etc. The lower the number, the lower the sensitivity and the finer the grain in your photos.
In digital photography, ISO is measured by the sensitivity of the image sensor. The values are the same as in analogue photography. The lower the number, the less sensitive the camera is to light and the finer the grain of the image.
Higher values mean that the sensor is more sensitive, allowing the camera to be used in dark conditions.
The downside is an increase in graininess. Nowadays, many cameras can use high ISO settings and still produce very usable images.
Every time you double the ISO value (for example, from 200 to 400), the camera needs half as much light for the same exposure. If the camera needs 1/125 of a second to take a picture at ISO 200, ISO 400 will provide the same exposure in 1/250 of a second. This is why high ISO settings are so often used indoors and at sporting events.
Today, most digital cameras can take good-quality photos at ISO sensitivities of 1600 and above. One important factor affecting the amount of digital noise in an image is the size of the pixels used on the sensor.
Larger pixels produce less noise, which is why DSLRs perform much better at high ISO settings than compact cameras. DSLRs have larger sensors and larger pixels.
Another factor is the amount and type of noise reduction. Every digital camera processes each image to minimise noise. Newer cameras use technologies that produce less noise at the same ISO sensitivity.
What is the base ISO?
The lowest ISO value on a camera is called ‘base ISO’.
This is a critical setting because it allows you to get the best image quality and minimise noise. Some older SLR cameras have a base ISO of 200, while most modern digital cameras have a base ISO of 100.
It is best to stick to the base ISO value to get the best image quality, but this is not always possible, especially when working in low-light conditions.
How to change ISO
The method for changing the ISO value depends on the camera you are using.
Most often, you need to exit the fully automatic shooting mode (set by the manufacturer by default). Instead of automatic mode, select a mode that allows you to change the shutter speed or aperture values yourself.
In the quick menu, find the ISO section and set the desired value, or set the value to ‘Auto’.
Higher-end cameras may have a dedicated ‘ISO’ button. Press it and turn one of the control wheels to change the sensitivity value. It's a good idea to read the manual just in case.
The ISO value is a setting that changes relatively often, especially if you take a lot of photos indoors in low light. Therefore, it is worth practising changing the setting quickly so that you don't miss the shot you wanted to take at a critical moment.
On smartphones, ISO settings are usually found in the advanced or manual mode of the camera app. Unfortunately, not all smartphones allow you to quickly change camera settings manually.
Remember that changing the ISO is not the only way to make a photo brighter. If you think the ISO is too high, try opening the aperture wider. This will lower the ISO and reduce the amount of noise in your photos. However, a wider aperture means a loss of depth of field.
When to use a low ISO
You should always keep the ISO as low as possible to get the best photo quality.
ISO 100 or 200 is best when you can. These low values are most often used in great lighting, especially if you're shooting handheld. A low ISO is perfect for shooting landscapes during the day, for example.
Low ISO settings can sometimes be used in dark conditions, but this will require a longer exposure time. Any vibrations, even those caused by breathing, will blur the photo. Therefore, in low light, low ISO settings should only be used when the camera is stable, for example, on a tripod.
Remember that with a long exposure, any moving objects will appear as blurry spots.
When to use high ISO
In many situations, you need to use a high ISO value to get a good photo.
This is most often because you are trying to take a photo handheld in low light (which causes camera shake) or you are photographing moving subjects, such as people dancing in a room lit by light bulbs.
When shooting in low light, the shutter speed tends to slow down, resulting in blurry photos due to camera shake or subject movement. In such situations, a prolonged exposure is not possible. To avoid problems, increase the ISO setting to a higher value, such as 1600.
Noise in a photo is the price you pay for avoiding blur. A high ISO setting is also practical when you are trying to capture fast-moving subjects in good light, as it allows you to minimise the shutter speed and reduce blur, for example, of a car or an athlete.
Of course, you can use a flash in such situations... but it's better not to. Nothing kills the atmosphere of a photo like a misused flash. If you shoot using only the existing light, you have a chance to capture all the play of light, the subtleties of lighting, and the delicate looks and gestures.
With the flash on, you kill the atmosphere with a bright white glow, and you'll never take a good photo. It's better to spend time understanding how to use your camera settings, including ISO and aperture.
Should you use automatic ISO mode?
Don't worry if all this sounds complicated; most people set their digital cameras to automatic mode.
In this mode, the camera selects the appropriate ISO setting depending on the conditions in which you are shooting. Enabling this feature allows the camera to increase the ISO when it decides that the shutter speed is too slow to take a good picture.
This setting often works well. Most of the time, you will be allowed to enter the maximum ISO value you want to use, such as 800, 1600, or 3200, and the camera will not exceed this limit.
Conclusion
ISO is an essential aspect of digital photography that you should understand if you want to gain more control over your digital camera. So experiment with different settings.
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