What is ISO? The Complete Guide for Beginners
ISO is one of the three pillars of photography (the other two being shutter speed and aperture), and it has a major effect on your images. How does camera ISO affect your images? In this article, I will introduce ISO for beginners and explain how to use it effectively for the best possible results.
What is ISO?
In very basic terms, ISO is simply a camera setting that will brighten or darken a photo. As you increase your ISO number, your photos will grow progressively brighter. For that reason, ISO can help you capture images in darker environments, or be more flexible about your aperture and shutter speed settings. However, raising your ISO has consequences. A photo taken with an ISO that is to high will show a lot of grain, also known as noise, and might not be usable. So, brightening a photo via ISO is always a trade-off. You should only raise your ISO when you are unable to brighten the photo via shutter speed or aperture instead.
What is the Meaning of ISO?
The acronym ISO stands for “International Organization for Standardization”. However, camera ISO does not directly refer to the organization that creates various technology and product standards. Ever since two film standards called ASA and DIN were combined into ISO standards in 1974 (later revised for both film and digital photography), they were referred to as one word “ISO” from that point on. Although ISO initially defined only film sensitivity, it was later adopted by digital camera manufacturers to maintain similar brightness levels as film.
Common ISO Values
Every camera has a different range of ISO values (sometimes called ISO speeds) that you can use. A common set is as follows:
- ISO 100 (low ISO)
- ISO 200
- ISO 400
- ISO 800
- ISO 1600
- ISO 3200
- ISO 6400 (high ISO)
Quite simply, when you double your ISO speed, you are doubling the brightness of the photo. So, a photo at ISO 400 will be twice as bright as ISO 200, which will be twice as bright as ISO 100.
What is Base ISO?
The lowest native ISO on your camera is your “base ISO”. This is a very important setting, because it gives you the potential to produce the highest image quality, minimizing the visibility of noise as much as possible. Some older DSLRs and several modern cameras have a base ISO of 200. Most modern digital cameras have a base ISO of 100. Optimally, you should always try to stick to the base ISO to get the highest image quality. It is not always possible to do so, especially when working in low-light conditions.
How to Change ISO
Changing ISO varies from camera to camera. Here are some common ways to change ISO:
- To start, enter a mode that lets you select the ISO yourself. Get out of Auto mode, and go to Manual, Shutter Priority, Aperture Priority, or Program (we tend to prefer Aperture Priority or Manual).
- For entry-level DSLRs and mirrorless cameras, you probably need to open a menu (possibly the “quick menu”) and find the section for ISO. Select the value you want, or set it to Auto.
- For higher-end cameras, there may be a dedicated “ISO” button on the camera. Press it while spinning one of the wheels to change your ISO setting. If you don’t see a button labeled “ISO”, it is still possible that your camera will let you program one to perform this task.
- Other cameras may have a dedicated wheel that already has various ISO settings marked. This makes things even easier.
Check your camera manual if you still aren’t sure. However, it is worth being very familiar with how to change your ISO setting quickly, since it’s something you will likely be adjusting quite often, especially if you shoot in low light conditions without a tripod or flash.
What Camera ISO Should You Use?
Many photographers understand the basics of ISO, but sometimes they are not always sure which ISO value to select. In practice, there’s a reason why your camera allows such a wide range of ISO settings: Different situations call for different ISOs. Below, I will cover some of the common scenarios you may come across.
When to Use Low ISO
As discussed above, you should always try to stick to the lowest ISO (base ISO) of your camera, which is normally ISO 100 or 200, whenever you can. If there is plenty of light, you are free to use a low ISO and minimize the appearance of noise as much as possible. Even in dim or dark environments, you still might be able to use a low ISO if you have your camera mounted on a tripod or sitting completely still on a table. In that case, you can safely use a low ISO and brighten your photo via a long shutter speed instead, since you won’t introduce camera shake. However, keep in mind that if your camera does use a long shutter speed, anything that is moving will look like a ghost.
When to Use High ISO
Even though it is ideal to use low ISOs, there will be plenty of times when a high ISO is necessary in order to take a good photo in the first place. The simple reason is that you are often fighting against motion blur, and you will need to pick between a sharp photo at a high ISO, or a blurry photo at a low ISO. You should increase the ISO when there is not enough light for the camera to capture a sharp bright photo any other way. When I shoot handheld photos indoors without a flash to capture the moment without introducing blur. When photographing ultra-fast action like in the birds raising your ISO is often necessary. On most cameras, there is a setting for Auto ISO, which works great in low-light environments. The setting is that you input the maximum ISO you are willing to use so that the camera does not cross that limit. If you want to limit the amount of noise in a photo set the maximum ISO to something like ISO 800, 1600, or 3200. The downside is that the camera will start using progressively longer shutter speeds if it reaches these ISO limits, which leads to more motion blur.