What Does ISO Mean in Photography?

Understanding what ISO is in photography and using your digital camera accordingly is essential for capturing great grain free images. What does ISO mean and what are the ideal ISO settings for different types of photography are the questions we decided to answer to in a more in depth manner.

What Does ISO Mean?


ISO is one of the three pillars of photography along with Aperture and Shutter Speed. We have already touched both on the ISO meaning and its importance when we discussed how to make the most from your camera exposure. However, there’s always more useful information to provide on the subject, especially for beginners.

To put it simple, ISO refers to how sensitive your digital camera or film is to light. So anytime we talk about ISO photography, we refer to the ideal amount of light we need for well-exposed images. Both in film and digital photography, ISO indicates the sensitivity to light and is measured in numbers – 100, 200, 400, 800 etc. These numbers are established by the International Organisation for Standardization. Here are the ISO standards used in photography:

ISO Standards used in Photography - ISO scale

Back in the film photography days, an ISO of 100 was best for shooting in natural light, while 400 ISO was commonly used for indoor photography.

In our digital age, though, ISO settings allow you to better control the quality of your photo. As compared to film, on digital cameras you can set a different ISO for each shot. So, in case you come across situations when you cannot use flash, you can rapidly switch your ISO up to 3200 and make the image sensor more sensitive to light. With film, the higher the ISO, the more grainy and noisy the pictures were.

How does ISO work? The lower the ISO is, the less sensitive your camera will be to light. A higher ISO number is thus necessary in low light conditions. This, unfortunately, increases the noise of your shots, which means that finest images are always achieved in natural light.

experimenting with iso settings

Experimenting with ISO Settings

Base ISO

All digital cameras have a so-called base ISO which is the lowest ISO you can use to capture high quality images. While most of Nikon cameras have a base ISO of 200, the typical base ISO for Canon is 100.  ISO 100 is the lowest recommended ISO for digital cameras, but the number can drop to 80, 64 and even 50 depending on light conditions and shooting purposes.

The ISO number can be increased from 100 or 200 to 400, 800, 1600, 3200, 6400 end even higher. The highest the ISO is, the less time is needed to capture an image. For instance, ISO 100 has a capture speed of 1 second, while ISO 1600 speed is sixteen times lower.

Auto ISO

Many digital cameras have a special setting called Auto ISO. How does Auto ISO work? Auto ISO is great for low-light shooting. All you need to do is set a maximum ISO number to limit the grain in your image, such as ISO 800, and the camera will automatically change it based on the amount of light available.

auto iso settings for Canon

Auto ISO for Canon Digital Cameras

ISO, Aperture and Shutter Speed

Before experimenting with different ISO settings, it is important to learn more about Aperture and Shutter Speed which with ISO are part of the Exposure Triangle.

Light and noise are affected not only by the ISO number, but also by how fast the shutter speed and how large the aperture are set. A slower shutter speed means a longer time for the light to hit the image sensor. Also, the larger the aperture is, the more light will get through the lenses.

A low ISO goes hand in hand with a larger aperture. The less sensitive is the image sensor, the more light will need to get through the lenses. Also, when using a lower ISO, it is advisable to set slower shutter speed so that the light is delivered into the sensor over a longer period of time.

Consequently, if we set the ISO high, we need less light over a shorter period of time.

ISO Settings by Types of Photography

Next, we are going to answer to how to use ISO on your digital camera according to different types of photography.


Low ISO numbers, such as 100 or 200, are perfect for shooting in bright light. Natural light allows you to stick to a low ISO which will result in a higher quality and less grainier or even grain free images. A low ISO is ideal for all types of outdoor photography, be in landscape, nature, flower or travel photography as long as the sunlight is your friend.

Flower at ISO 100

Flower Captured at ISO 100

Low ISO can be used in dark settings as well, if you wish to add a dramatic effect to your photographs. However, if you want to lower the ISO number and there is little light to work with, you should also use a tripod or hold your camera steady by placing it on a flat, solid surface.


High ISO is mandatory in low light conditions. In order for your shot to be well-exposed, don’t forget to set a faster shutter speed as well after increasing the ISO number.

Usually, higher ISO settings are needed for indoor photography when shooting:

  • Indoor Sport Events
  • Art Gallery Shows
  • Parties and Weddings
  • Interior Design Photography
low light examples of ISO settings

Low Light Examples of ISO Settings for Indoor Photography

In certain circumstances, you can use a flash instead of increasing the ISO, but the images will probably get noisier and grainier.

We hope we provided you with useful answers to ‘what does ISO mean?’ and ‘how does ISO work for stunning results?’. If you have any other questions or comments, just drop us a line.

Image Sources: 1,2,3,4

Make the Most from Your Camera Exposure (ISO, Shutter Speed and Aperture)

The basic key to taking good pictures is learning to make the most out of your camera exposure features, which unfortunately is something most beginners don’t look into. Most DLSR cameras now have “auto” modes that adapt the camera to the lighting conditions, enabling their users to not look into those settings themselves, but the results obtained using the camera’s auto mode are far from satisfactory. Also, no matter how much you play with your pictures afterwards in a photo editor like Picassa or even Photoshop, even if you use the most sophisticated auto-contrast and auto-lighting tools, you pictures still won’t be that great.


The only thing that can make them truly spectacular and vouch for your truly professional photography skills is using the right camera settings in the first place instead of resorting to post-editing. Those camera exposure settings you should learn more about are sometimes called the camera exposure triangle: we’re talking about ISO, shutter speed and aperture. Here’s a short introduction on what you can do with each of those.

Camera Exposure Feature No 1: ISO

We’ve already talked to you about the importance of adjusting your ISO when we discussed a few tips on taking better family portraits. The ISO is a number reflecting your camera’s sensitivity to the available light. A lower number reflects a lower sensitivity (and must thus be used when there’s plenty of good light), while a higher number reflects a higher camera sensitivity. ISO 100 and 200 are considered low in most circumstances, 400 would be a medium, while every number bigger than that would be a high value. Greater ISO also comes with a cost: the higher the camera’s sensitivity, the more “grain” or noise in the photo’s quality. Still, when the lighting is poor or you’re trying to photograph a moving target, the payoff may be worth it. Experiment with this setting, get to know your camera and decide for yourself.

Camera Exposure Feature No 2: Shutter Speed

The second setting from the so-called camera exposure triangle which you should learn about is the shutter speed. This is a number reflecting the length of time for which a camera shutter is open for exposing light inside the camera sensor. Since we’re talking about advanced cameras here and not hundreds of years models, this number will obviously be a measure of fractions of a second. Really fast shutter speed settings (like 1/115) can successfully be used to freeze motion, while deliberately low speeds (like 1/15 or 1/20) can allow more light into the camera, making this a perfect setting for nighttime photography.

Camera Exposure Feature No 3: Aperture

Last, but not least, we should talk about the aperture feature. This is more like a technical built-in characteristic of the camera itself, referring to the hole with a lens through which light passes into the camera body. The larger this hole is, the more light can pass, making the camera more apt for certain types of photography. The depth of field (usually expressed through the letter f and is sometimes called the focal ratio) also depends on the camera’s aperture, and this refers to the portion of a scene which appears to be sharp. The larger the aperture, the smaller the depth of field will be and vice-versa.

Now remember: the important thing, besides learning how to use each of these better, is learning how to use them together. That means that if you increase one, maybe one of the others needs to be slightly decreased to compensate, and so on. For example, a large aperture usually calls for a high shutter speed, to prevent overexposure and so on. We can’t provide you with exact formulas here, because all this adjusting would depend not only on what your current camera settings are, but also on what exactly you’re trying to photograph, if it’s indoors or outdoors, in what kind of lighting conditions and so on. You need to research these things yourself, starting with your camera’s manual. Once you’ve managed to get those camera exposure features to work for you, the most important technical requirements for great pictures have been met.