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What is the Maximum Aperture?

The Basics:

The maximum aperture - expressed in f-numbers or f-stops (for example f/2.8) - is the limit to how wide a lens can be open. Basically, it is the hole in your lens with the largest diameter, allowing the most amount of light to travel through the lens to the film plane. The Maximum Aperture is always included in the naming convention of the lens, for example EF24-70mm F.2.8L II USM.

The maximum aperture of a camera can really impact the type of photos you can produce and lenses with a wide maximum aperture has definite benefits. For one thing, the aperture size directly impacts depth of field. The lower the f-number, the shallower the depth of field. A higher aperture is preferred by portrait photographers, for example, as only the subject is in focus and the background can be blurred to draw the viewer’s attention fully to the subject. A wider maximum aperture can also help prevent camera shake and cut back on motion blur as it allows you to use a faster shutter speed.

See Aperture for more information.