If you need to take pictures with your Canon 500D in low light conditions or where flash photography is not allowed, your camera can compensate by adjusting the ISO setting. ISO settings vary, the higher the number, the more light is allowed on the sensor. If your camera is set to auto mode, the camera automatically determines the ISO setting, so you’ll need to set a creative mode to manually determine the ISO value.

To set the ISO mode manually, turn the mode selection dial to one of the creative modes (Tv, P, or Av) and then use the ISO button on the back of the camera to adjust the ISO value. Some typical examples of the correct ISO setting for your Canon 500D are, for example, 100 on a bright summer day, 400 for shots in shaded areas, to 1600 for shots in gloomy cathedrals or at night.

The Canon 500D is capable of boosting its ISO setting to a maximum of 12800, which is three steps better than the previous maximum available on the Canon 450D. One downside of allowing this extra light onto the camera sensor is that the image can start to appear grainy. You will need to experiment with the shot by taking several pictures at different ISO settings until you find one that is acceptable. Also note that you may need a tripod to stabilize the camera and prevent blurring.

Another application for setting a higher ISO value is if you are using a telephoto lens at full zoom. It can be difficult to avoid camera shake in these circumstances, so you’ll want a faster shutter speed using the Tv setting to avoid this; however, this limits the amount of light reaching the sensor, which can lead to underexposure. The solution is to set the ISO value to a higher value by increasing the light.