Diaphragm (optics) photographic lens is called an iris diaphragm. In the early years of photography, a lens could be fitted with one of a set of interchangeable diaphragms , often as brass strips known as Waterhouse stops or Waterhouse diaphragms. The iris diaphragm in most modern still and video cameras is adjusted by movable blades, simulating the iris of the eye. The diaphragm has two to twenty blades (with most lenses today featuring between five and ten blades), depending on price and quality of the device in which it is used. Straight blades result in polygon shape of the diaphragm opening, while
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