Zebras in Namibia

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Common Photo Problems – Digital Noise

Avoid Digital Noise

Digital noise is comparable to the “grain” you sometimes notice in film photography, as you see here in this noisy photo.  Not only do noise and film grain look somewhat similar, but they are also caused by similar factors.

Both are accentuated by high ISO levels, for example. ISO is a measure of your camera’s sensitivity to light, which you can increase to take photos in low-light situations.  You’ll always have some noise in your photos, even at your camera’s lowest ISO; but the higher you crank the camera’s ISO, the more noise that results.  Long exposures are also major contributors to noise:  The longer the exposure, the hotter your camera sensor gets–and all that heat contributes to digital noise in the final image.  It’s rarely a problem in daylight, but long exposures at night can fill your photos with noise.

So how do you avoid digital noise?  In general, shoot with the lowest ISO possible.  You might need to bump up your ISO when you’re shooting indoors without a flash, for instance, but don’t crank it all the way to ISO 1600 when ISO 800 might do.  Just increase the ISO until the shutter speed is fast enough to take a sharp photo, which is usually something like the inverse of the focal length.

Here’s an example: If the lens is set to 100mm, you can probably get a fairly steady shot with a shutter speed of 1/100 second.  Likewise, though longer exposures can lead to extra noise, you can fight back by turning on your camera’s built-in noise reduction.  Many cameras have an noise reduction feature that kicks in automatically or is applied to only certain types of noise.  If none of these features works for you or is available in your camera, you can always use your image-processing software to help reduce the noise.

Common Photo Problems – Red Eye

Prevent the Dreaded Red-Eye

Not to be confused with Pink-Eye, for which you should seek medical attention.

You’ll usually see the red-eye effect in low light, when your subject’s eyes naturally dilate to let in as much light as possible. When you fire your camera flash, the light passes through the open pupils and bounces off the back of the eye, which then looks red. That’s why you’ll never see red-eye in a photo taken outdoors in bright sunlight. To minimize the possibility of red-eye, take your pictures outdoors in daylight, or inside near a window where you have natural lighting. At night, brighten the room by turning on all the lights you can.

If you’re stuck in a dimly lit room or if you’re outdoors at night, turn to your camera for help. Your camera’s red-eye reduction mode (usually identified by an eye-shaped icon) fires the flash several times quickly right before the camera takes the picture, forcing your subject’s pupils to close down to a smaller size. Remember that the picture hasn’t been captured at the first sign of flash, so hold the camera steady–and warn your subject to hold still for a few seconds, to be sure that the camera is done taking the photo.

Your camera’s red-eye mode can help, but it isn’t a cure; you still might end up with red-eye in some photos. When that happens, use the red-eye tool in your favorite photo editor to blot out the red.