Lens flare

Lens flare is the light scattered in lens systems through generally unwanted image formation mechanisms, such as internal reflection and scattering from material inhomogeneities in the lens. These mechanisms differ from the intended image formation mechanism that depends on refraction of the image rays. Flare manifests itself in two ways: as visible artifacts, and as a haze across the image. The haze makes the image look "washed out" by reducing contrast and color saturation (adding light to dark image regions, and adding white to saturated regions, reducing their saturation). Visible artifacts, usually in the shape of the lens iris, are formed when light follows a pathway through the lens that contains one or more reflections from the lens surfaces.

Flare is particularly caused by a very bright light sources either in the image – which produces visible artifacts – or shining into the lens but not in the image – which produces a haze. Most commonly, this occurs when shooting into the sun (when the sun is in frame or the lens is pointed in the direction of the sun), and is reduced by using a lens hood or other shade.

DEFCON

The defense readiness condition (DEFCON) is an alert state used by the United States Armed Forces.

The DEFCON system was developed by the Joint Chiefs of Staff (JCS) and unified and specified combatant commands. It prescribes five graduated levels of readiness (or states of alert) for the U.S. military. It increases in severity from DEFCON 5 (least severe) to DEFCON 1 (most severe) to match varying military situations.

DEFCONs are a subsystem of a series of Alert Conditions, or LERTCONs, which also include Emergency Conditions (EMERGCONs).

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Operations

The DEFCON level is controlled primarily by the U.S. President and the U.S. Secretary of Defense through the Chairman of the Joint Chiefs of Staff and the Combatant Commanders, and each DEFCON level defines specific security, activation and response scenarios for the troops in question.

Different branches of the U.S. Armed Forces (i.e. U.S. Army, U.S. Navy, Air Force) and different bases or command groups can be activated at different defense conditions. In general, there is no single DEFCON status for the world or country and it may be set to only include specific geographical areas. According to Air & Space/Smithsonian, as of 2014, the worldwide DEFCON level has never risen higher than DEFCON 3. The DEFCON 2 levels in the Cuban Missile Crisis and 1991 Gulf War were not worldwide.