ISO refers to your cameras film speed, in traditional film cameras it would refer to the film sensitivity to light. Now in the digital age it is a determination of how sensitive the sensor is to light. The higher the ISO, the more sensitive the sensor is to light. Which would give you an opportunity to take pictures in low light situations such as The Haunted Mansion. There is a down side to a higher ISO setting though. As you increase the ISO the more noise (comparable to graininess in film) you will have in your photograph. The image sensor in your camera is an analog device that generates its own noise. An image sensor is usually calibrated so that it gives the best image quality at its lowest possible ISO Speed. The amount of noise varies from camera to camera. Today's digital cameras are starting to have less noise in higher ISO than older cameras. Noise can be seen throughout the photo but usually appears in dark or shadow areas. Also newer desktop photography programs deal with noise much better than their older counterparts. Also if you are printing your photos no bigger than 4x6, you may not see any visible noise.
Here is a guide for what ISO Settings would be helpful (remember all cameras are different and you will have to adjust to see what your camera will produce and adjust accordingly):
- Auto ISO - digital camera automatically sets the ISO Speed.
- ISO 80 - for taking photos in bright light. Excellent for daylight photos of the Cinderella Castle on a Bright Sunny Day.
- ISO 100 - for extra sensitivity with little, if any, reduced image quality
- ISO 200 - Cloudy and overcast days. Acceptable Image quality, has some visable noise.
- ISO 400 - suitable for Indoor photography with or without a flash and fireworks. Great for Character meals
- ISO 800, 1600 and above - useful for taking photos in very low light. Best used in dark attractions like, Pirates of the Caribbean and The Haunted Mansion.
Here are examples of different ISO Setting and the amount of noise they produce
In the Set of photos above the first photo was taken at 100, 2nd photo 200, 3rd photo at 400 4th photo at 800, 5th photo at 1600, and the last photo at 3200. Since the first photo had a lower ISO Speed there is very little noise in the photo. The following photos ISO settings were increased and you can see how the noise gets worse. in future tutorials I will show you how to process the images above to reduce the noise in Photoshop CS5 and in Lightroom 3.
Now changing the ISO on your camera will affect your aperture and shutter speed. With a higher ISO you aperture will not have to be open as much , or you could have a faster shutter speed so you will not get motion blur.
Now the big question is should I increase my ISO setting? If it is a matter of choosing between not being able to take a picture and suffering a noisy image, I'd rather be able to take the picture at a high ISO and then try to clean up the noise afterwards in a noise reduction software.
To recap:
- ISO speed on your camera is an indication of the sensitivity of the cameras image sensor.
- The best image quality is obtained by having the lowest ISO setting on your digital camera.
- ISO will affect your aperture and shutter speeds.
- Using a higher ISO will add more noise to your photos.
- If using Auto ISO you have no control over what ISO your camera is using.
- If you are keeping your prints small like 4x6 you may not see any visible noise on the prints even though you see them on your monitor screen.