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.
1 DHEA supplements may interfere with other medications thus you should take it only under medical supervision. 2  If you're under the age of 40 and have normal DHEA levels (at least 130 mg/dL for women and 180 mg/dL for men) then DHEA supplements is not for you. If you're under the age of 40 and have normal DHEA levels (at least 130 mg/dL for women and 180 mg/dL for men) then DHEA supplements is not for you. 2  When taking DHEA you should monitor your blood levels every 6 months. 3  So far, there's still no reliable study on the long-term safety use of DHEA.