An Introduction to ISO in Photography

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When it comes to photography, ISO refers to the sensitivity that your camera has to light. The higher the ISO you are using the more sensitive the sensor on your camera will be, and the brighter the photos you take will be. Take a look at any photo sharing website and you will see photos that have not been taken using optimum

You will see ISO measured in numbers. The standard values are 100, 200, 400, 800, 1600, and 3200. However most cameras will offer a range of intermediate ISO values. In addition to this, most modern cameras have additional ISOs that are higher – ISO 6400, ISO 12800 and even ISO 25600.

We commonly associate ISO with digital cameras, but it is also used for film cameras as well with every film having its own ISO.

What is ISO?

Technically ISO stands for “International Organisation for Standardisation”. However, when it comes to photography all you really need to know is that ISO is the amount of sensitivity that your camera has to the light.

Why does ISO matter?

When you increase the ISO on your camera you are making your photos brighter, and that is why this is so important.

ISO effectively works with aperture and shutter speed – your two other exposure variables to create the overall brightness level that you will get from your image. If you set your ISO to 100 then your image is likely to be rather dark. Turn it up to 200 and it will be a little brighter, and so on. So if your image is looking particularly dark then you need to up your ISO.

This is particularly useful, and important, when you are shooting in a lower light, for example indoors, or outside at night. In fact, ISO can still be beneficial when you are shooting in decent light. A higher shutter speed may be needed if you want to catch something fast like a racing car, but unfortunately when you do this you reduce exposure, and this makes things darker. So you need to increase both shutter speed and ISO in order to compensate for this.

 There is unfortunately one significant drawback to ISO, so let’s take a look at that.

What is the drawback of high ISO?

The higher you make your ISO the more grain (or noise) you will see in your photographs. These are the speckles of colour you will find on your image that can really distort it. So whilst increasing your ISO offers you a much brighter image it will have more noise, and this is why you shouldn’t use a high ISO all the time. Keep it low and only increase it when needed.

ISO is much better now than it was even a few years ago, but it is important to remember to compensate.

When should you raise ISO?

Let’s look at a couple of examples of when you might want to raise ISO:

  • An outdoor sports event with a fast moving subject
  • Shooting a landscape with no tripod when you need depth
  • Shooting a landscape at night and you want to freeze the stars (reasonable shutter speed)
  • Portrait photography in a dark room or in the evening
  • Shooting an indoor event with limited natural light
  • Shooting in a church, building interior or art gallery
  • Shooting wildlife at either end of the day (particularly if you are using a fast shutter speed)
  • Shooting something fast-moving and you require ultra-fast shutter speed

When should you reduce ISO?

  • If you are using a tripod and shooting something motionless
  • For portrait photography in good light
  • For an event when you are using a flash or have plenty of natural light
  • You are using plenty of artificial light to photograph products

Hopefully you now have enough information on ISO to start considering it when taking your photographs. We hope this has helped you improve your photography.

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