ISO Basics In Photography

Published: 2021-04-11
Views: 504
Author: Editorial
Published in: Photography

Along with shutter speed and aperture, ISO is one of the three fundamental settings of photography that you can change while taking a picture to help you monitor the overall exposure.

ISO is one of the three foundations of photography (the other two are shutter speed and aperture), and it has a major impact on the quality of your photographs. What effect does the ISO setting on your camera have on your photos?

In this post, w-e'll cover the basics of ISO and show you how to use it effectively to get the best results. ISO is a camera setting that allows you to brighten or darken an image during capture.

ISO Values That Are Popular

You can use a different set of ISO values (also known as ISO speeds) depending on the camera. The following is an example of a typical set:

• ISO 100 is the highest level of ISO (low ISO)
• ISO 200
• ISO 400
• ISO 800
• ISO 1600
• ISO 3200
• ISO 6400 is a high-resolution camera (high ISO)

You can get more light in low light conditions by increasing your ISO above a certain amount, but that improvement in light comes at a cost in terms of picture quality.

The higher the ISO, the more digital noise or grain is visible in your photographs. Noise appears as small grains strewn across your picture.

For example, some pictures may be shot at a high ISO, but if you look closely, you can see tiny specks all over the picture.

The sensitivity can be measured on a scale of 100, 200, 400, and so on, with a lower number suggesting less light sensitivity.

So, if you picked up a roll of ISO 100 film, you already knew that it would be best for images taken in bright lighting conditions due to its relative light sensitivity. 

You also realized that a roll of ISO 400 film was ideally suited to low-light situations, such as indoor photography.

When digital photography became common, the method of measuring ISO remained unchanged.

That means that when you set your camera's ISO to 100, it will still be less sensitive than 200, which will be less sensitive than 400, and so on.

The most significant change is that, where ISO once referred to the physical qualities of the film you were using, it now refers to an electronic process inside your camera.

ISO in digital photography

In digital imaging, ISO stands for Image Stabilization Index. It is a measurement of the image sensor's sensitivity in digital photography.

The same rules apply to digital photography as they do to film photography:

The lower the amount, the less light-sensitive your camera is and the finer the grain it produces. Higher numbers indicate that your sensor is more light-sensitive, allowing you to use your camera in low-light conditions.

More grain comes at a cost, though cameras are getting better all the time. Many cameras today can shoot at high ISOs and still produce usable images.

When it comes to ISO, there are a few situations where you may want to go for a higher setting:

If you're photographing an indoor sporting event with low light and a fast-moving subject. In this case, a higher ISO allows you to use a quicker shutter speed to freeze the athletes' movement.

Relationship between ISO, Shutter speed and Aperture

Since ISO influences the amount of light that enters your camera, it has an impact on shutter speed and aperture, and therefore your camera's exposure.

Consider the following scenario: your camera is set to ISO 100, the shutter speed is 1/125th of a second at f/5.6, and the exposure is perfect.

Your picture would be overexposed if you raise the ISO to 200 because your sensor will be twice as sensitive to the light coming in. To regain proper exposure at ISO 200, you'd have to raise the speed of your shutter, reduce your aperture (larger f-number), or both.

The same can be said for the opposite situation. Assume your camera is set to ISO 800, shutter speed 1/125ths of a second, and aperture f/5.6, and the image is properly exposed.

If you lower the ISO to 400, your image becomes underexposed because you've minimized the sensitivity of your camera sensor to light by half by lowering the ISO.

To regain proper exposure, you'd have to lower the speed of your shutter, open up your aperture (smaller f-number), or do both.

Choosing the Correct ISO

Here are some general guidelines for determining the correct sensitivity level for the digital sensor on your DSLR or mirrorless camera.

1. ISO 100 is the best option for shooting outdoors on bright days, which is the brightest situation you'll likely encounter.
2. ISO 400: A slightly higher ISO is best when the lighting is still good, but less harsh, such as indoors by a window or outdoors on a gloomy day.
3. ISO 800: You'll be working in this range if you're shooting indoors without the use of a flash.
4. ISO 1600 or higher: You'll need a high ISO when it's dark outside or you're shooting indoors in low light. If there's a lot of movement, you'll want to use a high ISO and a fast shutter speed.