Photography Tip—Understanding Auto ISO and Its Limits
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Digital photography and film photography share a concept that essentially works the same in both types of camera. The light sensitivity of a digital camera’s sensor and a film’s surface is designated by a numerical value. In digital photography, this is known as ISO, an acronym for International Organization for Standardization, which sets those values. In film-based photography, it’s called ASA (American Standards Association).
Traditional film photographers must shoot each roll of film at the same ASA setting, which makes it difficult to shoot both outdoors and indoors with the same roll of film. Digital photography changed all that because it’s technology allows photographers to change the ISO from photo to photo, regardless of where they are shooting. Then, the ISO concept advanced even further when cameras were manufactured with Auto ISO. Not only could you shoot at a different ISO for each photo, but also the camera selected the correct setting, so you could concentrate on composing a better photo.
Every technological improvement is not always total, however. Auto ISO was smart, but not smart enough to take into account the digital noise that occurs in pictures at higher ISO settings. Many digital cameras’ sensors will start to produce noise at approximately ISO 400 or 800. As the photographer, however, you want to eliminate or reduce noise to the minimum; otherwise, your photos are essentially ruined or not what they could be. To overcome this flaw in Auto ISO’s brain, photographers had to set ISO manually again.
Then, the manufacturers recognized this flaw (as well as customers telling them to fix it) and redesigned their cameras to have the capability to limit Auto ISO. With today’s cameras, you have more control of the ISO, so they don’t automatically choose an extreme setting that results in unwanted noise. Your owner’s manual should have all the information you need about how to limit Auto ISO on your camera.
You must also be conscious of the maximum Auto ISO you will allow. There is not an exact maximum; it depends on how much noise you will accept. Many of the experts, however, recommend Auto ISO to be no more than 400. This is an excellent opportunity to experiment with your camera by shooting at various ISO settings under a range of lighting conditions. Having samples to compare are the perfect aids to learn, understand and use this concept to your advantage.
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