1 Leaf shutters are usually fitted within a lens assembly (central shutter), or more rarely immediately behind (behind-the-lens shutter) or, even more rarely, in front of a lens, and shut off the beam of light where it is narrow. 2  Focal-plane shutters are mounted near the focal plane and move to uncover the film or sensor.
DHEA levels begin to naturally decline by the age of 30. While normal levels for women in their 20s fall between 65 and 380 Âµg/dL, for women in their 30s and 40s, the average normal range is 45 to 270 and 32 to 240 Âµg/dL, respectively.
Normal Ranges. The normal range describes the range where 95% of the normal healthy population will lie. This also means that there is 5% of the normal healthy population will fall outside the normal range, however they too are normal. Normal ranges are a guide.he normal range of ALT levels is between 5 IU/L (International Units per Liter) and 60 IU/L. The normal range of AST levels is between 5 IU/L and 43 IU/L. Elevated liver enzymes may be a sign of hepatotoxicity (liver toxicity).