Back button focus is a technique used in photography that separates the focusing and shutterEither mechanical and/or electronic shutters are possible. Mechanical systems can use a leaf (or iris) shutter or curtain shutter. In digital cameras a third alternative is also possible: the electronic shutter. This works by activating and then deactivating the CCD so that no further light can be recorded, regardless of whether light is hitting the CCD. The shutter controls the exposure time, which can range from thousandths of a second to several minutes or more. Fast shutter speeds freeze action, slow speeds are more suited to stationary subjects. A tripod is recommended for slow exposure shots to avoid camera shake, or IBIS. release functions on a digital camera. Instead of the default setting, where the shutter buttonEither mechanical and/or electronic shutters are possible. Mechanical systems can use a leaf (or iris) shutter or curtain shutter. In digital cameras a third alternative is also possible: the electronic shutter. This works by activating and then deactivating the CCD so that no further light can be recorded, regardless of whether light is hitting the CCD. The shutter controls the exposure time, which can range from thousandths of a second to several minutes or more. Fast shutter speeds freeze action, slow speeds are more suited to stationary subjects. A tripod is recommended for slow exposure shots to avoid camera shake, or IBIS. is used to both focus and capture an image, with back button focus the user assigns the focusing function to a button on the back of the camera (usually the AF-ON button). This allows the user to focus independently of capturing the image. This can be useful in situations where you want to lock focus and recompose the shot before taking the picture. For example, putting a near object in focus within a wider composition.
