With the sensor technology becoming a very important issue in digital photography, it is important to understand what this means for your photographs and for your new camera selection.
ISO, what is it?
If you try to track down the definition of ISO, you’ll be met with a lot of confusing mathematical terms and definitions that do a great job of telling what engineer-speak ISO settings are for you camera. I’ve never been much for extremely difficult to understand definitions. So, here we go with the basic one.
ISO is the comparison for the sensitivity of the film you used to use in an old-school film camera. The lower the ISO setting on the camera, the less work the camera has to do to “read” the image in front of it.
For those of you who remember the 35mm camera, you would purchase film with an ISO or ASA rating: ISO 100 was for bright sunny days, ISO 400 was generally an all-purpose indoor/outdoor film, ISO 800 or 1600 was great for shooting nighttime pictures and fireworks. If you had an ISO rated film that was incorrect for the type of picture you were shooting, you had to change the usually incomplete roll of film in the camera and start shooting with a brand new, (ISO corrected), roll of film.
With today’s new ISO equivalent cameras, the settings are unbelievable, now the ISO ratings are in excess of 12,800. You can almost shoot in the dark.
But…, here it is… the but. Usually, with the higher ISO setting used on the camera, the camera sensor has to work much harder, and the pictures taken will show a type of “graininess” that makes your picture look like it was taken with a 1930′s newspaper camera and some of this graininess or “noise” can be eleiminated from your image, but with this eleimination of “noise”, comes a loss of detail or sharpness.
Warning: Technical information ahead: Basically, what happens is that the electrons inside of the camera have to work harder to “read ” the image in lower-light situations. This electron noise is caused by the electrons on the sensor heating up the sensor and leaving heat footprints from how hard they worked to do the job for you. The best possible solution, when it is feasible, is to make the camera sensor work less to capture a sharper, “noise-free” image.
So, the rule to remember when setting your own ISO setting on the camera. Use the lowest possible setting to get a good picture with your particular camera. Digital photography magazines and websites will often offer a “noise” comparison example for the specific model of camera you are looking at, and they are a great way to preview the specific camera’s highlights and weaknesses relating to digital noise.
Hope this helps, take better pictures and have fun.