Show Me The Light!
Understanding Your ISO

One of the great advancements in the conversion from film to digital photography is the ability to change the ISO, or film speed, with any picture. With film, photographers were stuck with an ISO, or ASA, for 12, 24, or 36 exposures. Today, a camera's sensitivity to light can be changed with push of a few buttons, allowing advantages that previous photographers could only dream of.

ISO, or International Standard Organization, is a group of people that get together to determine the standard measurements for the world. For photography, they determined what qualified any certain film's sensitivity to light and gave it a numerical value. Most 35mm photographers used 100, 200, or 400. Here in America, we have our own "standard" as well, ASA, or American Standard Association, so you may of heard film called "100ASA." Digital cameras are sold all over the world, that's why ISO is used instead of ASA.

For photographers, changing the ISO setting on your camera allows you change the camera's sensitivity to light. In lower light, you can turn the flash off and shoot in existing light by raising the camera's ISO number. Auto ISO usually defaults to a lower number and the camera fires the flash. With the flash intentionally turned off, and the ISO number set higher, you will have the ability to take pictures indoors, given there's enough light to get a fast enough shutter speed for a correct exposure.

When a camera is set to program, usually labeled with a P, the camera reads the light and sets the f/stop and shutter speed. This is point-and-shoot at it's best. Sometimes, the camera may fire the flash when natural light would actually look better. The camera may also choose a shutter speed that is too slow to be handheld for a clear picture, or too slow to capture the action. Now that we have the capability to change the ISO easily, we can adjust the ISO to a higher number, making the camera more sensitive to the light. As previously stated: If there's enough light available, with the camera set to a higher ISO, you can turn off the flash and shoot with available light. In addition, raising the ISO will also force the camera to use a faster shutter speed, which may be fast enough now to handhold the camera or stop the action your trying to capture.

So what's the catch? Noise. We called it film grain when we shot 35mm: As the ISO number goes up, photos become more and more "grainy." Digital noise equals tiny bits of misinformation that get in the way of the overall clarity of the photo. As the ISO is raised, our photos don't look as sharp, crisp, or clean because of the noise. I think it's a worthwhile trade-off when trying to shoot candid, nothing kills candid photography like a flash going off, and the artificial quality of flash photography can be unflattering at best.

It's time to experiment: This will work best if you're in your living room, or inside somewhere.

• Grab your camera and set it to P for Program, (which is different than the green "auto" setting that won't let you override any features.) Some cameras have a red camera icon that stands for program, just in case your camera doesn't have a "P" mode.
• Take a picture of your computer screen or tv from at least five feet away.
• Now look for the flash icon; it looks like a lightning bolt with an arrow at the bottom. If it's not an obvious button, try looking on or around the toggle switch, (the up/down/left/right control switch.) Once you find it, push it a few times until you see the symbol for "no flash," a circle with a line through the lightning bolt.
  
• Take another picture of your computer screen from the same spot as the first one.
• Now it's time to change your ISO. You may find the letters ISO somewhere on or around your toggle switch, or by a button. (If you own a Canon, you may need to, depending on the model, push the FUNC (function,) button to activate a short menu selection on the left side of your screen. Toggle down to ISO for the different choices.) If it's not accessible on the outside of your camera, push the menu button and start toggling through the different choices, until you find ISO. Most cameras will have it labeled ISO, some call it Sensitivity.
• Start with the lowest number, usually 100, and take a picture from that same spot as above.
• Go back into your ISO and go up one level, 200. Take another picture, same spot.
• Go back into your ISO and proceed with a picture at every ISO number.

Now take a look at the shots. Push playback, usually a blue triangle. You should see quite a difference in the exposure, from dark and maybe blurry to bright and clear. You can also zoom into your photo by the the usual zoom button and scroll around the picture using the toggle switch. If you press DISP, you might be able to see the different f/stops and shutter speeds, depending on your camera model. Don't worry for now if the color looks yellow or off, we'll cover that it the future.

Well, this has been quite a bit of info, so in the next installment we'll start looking at the different preset camera settings such as portrait, landscape, sport, and night shots. Until then, practice and take a lot of pictures. Experiment. There is no combination of buttons you can push on your camera that will make it explode.