In this blog post I will explain what does ISO stand for in photography and how to make the best of a given situation when it comes to light.
Before we get into ‘What is ISO,’ let’s talk briefly about film speed.
Film speed measures the sensitivity of film emulsion to light and is measured in ISO (International Organization for Standardization) numbers.
The higher the number, the more sensitive the film, and therefore it can be used in lower lighting conditions. Not all films have an ISO rating; some are fixed at a particular sensitivity and cannot be changed.
The ISO rating is determined by the manufacturer. It is not always consistent across all types (e.g. for black and white films, an ISO 100 will produce a different image quality than that of color films).
What does ISO stand for?
ISO stands for International Organization for Standardization, which you can read more about here. This organization has created a rating system so the photographer knows how sensitive the camera’s sensor is to light.
The higher the number, the more sensitive it becomes, up to a maximum of ISO 3200 (more on this later). The base number for ISO is 100, and the numbers double every time you get to the next step.
So for example: ISO 200 will be twice as sensitive as ISO 100, and so on and so forth. However, there is no such thing as an ISO 50 or an ISO 0. These are just not physically possible.
How sensitive is each ISO number to light?
At ISO 200, you’ll get twice as much light than 100 and at ISO 102400 (the maximum number), you’ll get 1,048,576 times more light than an ISO 100 setting. This is why you don’t want to use such a high ISO setting unless absolutely necessary.
What do the different kinds of ISO mean?
Now that we’ve learned what ISO means in general, we’ll look at each of the different kinds of ISO you can choose from in your camera:
ISO of 100 is when you want to be when shooting outdoors. Not only does it have low noise, but it also gives you the most accurate colors. In situations where there is a lot of light available, an ISO 100 setting will provide you with very sharp images with vivid color.
Moving up to 200 is where things start to get interesting. While the amount of noise in your image might be noticeable straight away, ISO 200 will still produce excellent results when shooting outside. It’s not until you zoom into a photo taken at ISO 200 that you’ll see how much noise has crept up on you.
ISO 400 is where noise starts to become quite apparent. All of the colors in your image will start to become slightly grainy, even if it looks fine on your LCD screen or computer monitor at first glance. It’s best to use ISO 200 over ISO 400 when you’re shooting outside, but sometimes you just have no choice but to bump the ISO up to 400.
At 800, noise becomes apparent in all of your images, no matter how much you zoom in or try to hide it with filters. Colors will start to get muddy, but don’t worry – there are ways to get good-looking images at ISO 800. Using the right kind of camera filter or Photoshop treatment can fix all of your noise problems.
1600 is where the fun really starts. Noise is extremely noticeable, and it can ruin any kind of image – whether you’re shooting a landscape, a portrait or a nature scene. This ISO setting should only be used if you have no other options. The trick to getting good-looking images at this ISO setting is to either use noise reduction software (more on this later), or shoot in RAW.
3200 is where you should never, ever go unless it’s an emergency. With ISO 3200, your images will look like they were taken with a cell phone camera, regardless of what kind of lens you’re using. Nobody wants grainy, pixelated photos, so don’t use this ISO setting ever – not even when you think it might be necessary to do so.
Going as high as 6400 is almost as bad as ISO 3200 in terms of quality. There are a few good things about it, though: the colors aren’t too muddy, and you can use this ISO setting in dim-light situations. I mean dim-light conditions when there isn’t much light available and your subject is far away from you. In other words, don’t use ISO 6400 unless you absolutely have to.
ISO of 12800 shouldn’t even be considered by most photographers since the quality is really bad, but if you absolutely must get a good image out of a bad situation, then ISO 12800 is the way to go.
Going 25600 and higher should be avoided at all costs since they produce images that are practically unusable.
Fixing high ISO noise in Photoshop
So, now you know exactly how each kind of ISO setting will affect your image. But, what do you do if the photos you took at high ISO settings are grainy and pixelated?
In most cases, you’ll need to use a combination of Curves, Color Balance and Unsharp Mask to fix your grainy images. Here’s how: Open the image that has too much noise in Photoshop
Go to Filter > Noise > Add Noise. Make sure the amount is set to 100%, the Distribution is set to Gaussian, and that Monochromatic is unchecked.
In your Layers panel, change the blend mode of this Noise layer from Normal to Overlay. Depending on the amount of noise in your image, you might want to play around with the opacity of this layer as well.
Go to image> Adjustments > Curves and change the curve by adding a new point and dragging it downwards. Repeat this step until your image looks clean enough.
If you want, add another Curves layer and decrease its opacity if necessary. You can also add a Color Balance or Brightness/Contrast layer to finish off the noise-removal process.
The final step is to sharpen your image, but you’ll need to use Unsharp Mask since it gives better results than the Sharpen tool in Photoshop. Here are the settings that I recommend: Amount 100% Radius 1.0 Threshold 0 Once you’ve added these two layers, change their blend modes from Normal to Hard Light.
And there you have it – a noise-free image that looks as good as new! If your camera doesn’t support RAW, then the only way to reduce noise is by using low ISO settings or by capturing multiple images at once and combining them later on in Photoshop. The latter option will produce better results than the former, but it’s only suitable for stationary objects.
Marco Downs is is the creative head of this website. Marco stumbled upon photography only in college when he joined the photography club. His parents could never afford a camera for him as a child and it was in college that he saved up and bought his first camera. He now writes in-depth buyer guides and informational articles to assist the buyers.