Photography: Learning about ISO

February 19, 2016

Recently I have been learning how to use my camera. I have signed up to a photo course, A Year With My Camera which is proving very interesting. In the last couple of weeks I have been learning about exposure. To get the correct exposure on your photography you need to control several aspects of your camera, the aperture or the amount of light that gets into the camera, the shutter speed which is how long the light enters the camera for and the ISO. Getting these aspects right will create a picture that is not too light or too dark and captures the scene perfectly. If you are using your camera on auto it will do this for you. If you take your camera off auto you have more control. Aperture can be used to artistically blur the background. Shutter speed can be increased to capture fast moving objects without blur or decreased to create an artistic blur on the image. What is ISO though?

ISO is a measure of how sensitive your camera is to light. In the days of film you would buy film that had a certain ISO and use this till you finished the roll. For bright conditions you needed a low ISO and for dark conditions you needed a high ISO. These days the camera has a setting that you can change with every shot. To find out how to do this you need to read your manual, I could adjust my ISO by pressing a button on my display and changing it there. My ISO varied between 100 and 6400.

How ISO changes the shot

When I was experimenting with shutter speed I found that when I set the camera on a high shutter speed the image got very dark.  This is because the aperture changes to compensate for the shutter speed and less light gets into the camera. To get round this you can increase the ISO and make the camera more sensitive to light. To demonstrate this I took some photos of my dog using a high shutter speed.


The first image used ISO 100. The second image used ISO 6400. Can you see how the second one is much brighter? If you are taking a photo in dimly lit conditions you can also increase your ISO to let more light into the camera and get a better shot. This is a picture of my dog taken in a dimly lit room. Increasing the ISO made it look much brighter.


The opposite holds true as well, if the conditions are too bright you can decrease your ISO to stop the image being over exposed. There is a downside however, the higher the ISO the more noise and graininess you get in your picture. This makes the photo quality less. Hopefully with practice I will learn to judge the right settings for aperture, shutter and ISO in order to get the perfect photo.

Do you know how to change the ISO on your camera? Have you ever tried?

6 responses to “Photography: Learning about ISO”

  1. I learnt a lot of ISO settings through trial and error whilst trying to photograph the northern lights.

  2. Galina V says:

    Eddie is just so cute! I enjoy reading your photography tips, very useful to know.

  3. Eb Gargano says:

    Very interesting…I have just bought a dSLR camera…been so busy, though, I’ve not got it out of it’s box yet *sigh* but I am looking forward to learning all about ISO when I finally do! Eb x

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