Camera Modes

Auto ISO modes

Written by Gail Bjork

Auto ISO modes automatically select the ISO according to the light level of a scene. This means that the user has no control over which ISO number is used. This may…or may not…be a good thing.

Auto ISO mode

All consumer digital cameras have an Auto ISO mode. The camera automatically selects the sensitivity, known as ISO, according to the level of light in a scene. The user has no control over which ISO number is used.

In bright light a lower ISO will be selected. In low light an higher ISO number will be selected.

Auto high ISO mode

Some compact digital cameras have an auto high ISO mode that is primarily used in very low and difficult lighting. The camera selects ISO numbers higher than auto ISO mode, usually ISO 400 and above.

Higher ISO means faster shutter speeds

When a higher ISO is selected, shutter speeds are faster and apertures open wider, allowing more light to enter the camera. Use of faster shutter speeds helps prevent blurred images due to camera shake. When using high ISO numbers, you may not have to use a flash.

Higher ISO means more image “noise”

Keep in mind that the higher ISO, the more noise appears in images. That’s why many photographers, in order to prevent noise, prefer to set ISO manually and select low ISO numbers even if they must use a tripod to prevent camera shake. Still, an photo with noise is better than no photo at all.

Image noise will be higher when using Auto High ISO mode than using Auto ISO mode. Whenever possible, manually select ISO and use the lowest ISO setting possible.

About the author

Gail Bjork

Gail Bjork, who is passionate about digital photography, is the owner and editor of Digicamhelp.Gail is the author of three illustrated ebooks about digital photography. A number of her photos and digital photography related articles appear at other websites.In 2006, a series of her photos, People in the Louvre, were exhibited at the Underground Photo Gallery
in Iisalmi Finland. Eight of her photos taken in the Florida scrub are on permanent exhibition at Parrish Medical Center in Titusville, Florida.Gail served twelve years as an elected member of The School Board of Palm Beach County, Florida, one of the largest school districts in the U.S. She has also been the editor of a small town newspaper and a free-lance writer. Gail and her husband owned and ran several small businesses.


  • d jones, if the card is a Secure Digital memory card, it has a lock on the side of it. Slide it the opposite of the current position and it will unlock the card.

  • Please tell me what “card locked” means.  I loaned my camera to a friend and when received back that is what its saying and i cannot delete pictures the friend took.  Please Help!!!!

  • Not all cameras are created equal when it comes to high ISO performance, especially when it comes to compact digital cameras. If you have a compact camera that does well in low light then, yes, you may be able to give up using a flash in low light by increasing the ISO. Just don’t forget to change the white balance setting to match the lighting if you’re shooting indoors.

  • None of this novel before, and this information very valuable and useful in any case that the use of a camera with ISO means to give up the flash so is your opinion?!