Diaphragm (optics) the lens. The centre of the diaphragm's aperture coincides with the optical axis of the lens system. Most modern cameras use a type of adjustable diaphragm known as an iris diaphragm, and often referred to simply as an iris. See the articles on aperture and f-number for the photographic effect and system of quantification of varying the opening in the diaphragm. A natural optical system that has a diaphragm and an aperture is the human eye. The iris is the diaphragm, and the opening in the iris of the eye (the pupil) is the aperture. An analogous dev in a
Thoracic diaphragm more consistently lower position of the diaphragm increases intra-abdominal pressure which strengthens the lumbar spine. The key to real core stabilization is to maintain the increased IAP while going through normal breathing cycles. […] The diaphragm then performs its breathing function at a lower position to facilitate a higher IAP. Therefore, if a person more consistently lowers their diaphragm, through deep breathing, this can assist strengthening of the core during that period. This can be an aid in strength training and other forms of athletic endeavour. For this reason, taking a deep breath, or adopting a deeper breathing pattern, is