Two-second rule two seconds as inadequate, and recommend a three-second rule. German law requires a minimum 0.9 second distance but when tested under relaxed conditions researchers found that their test subjects spent 41% of the test time at following distances under 0.9 second. The United States National Safety Council suggests that a three-second rule—with increases of one second per factor of driving difficulty—is more appropriate. Factors that make driving more difficult include poor lighting conditions (dawn and dusk are the most common); inclement weather (ice, rain, snow, fog, etc.), adverse traffic mix (heavy vehicles, slow vehicles, impaired drivers, pedestrians, bicyclists, etc.), and
Sunny 16 rule is to set shutter speed nearest to the reciprocal of the ISO film speed / setting and f-number according to this table: This is a scene of average brightness, in direct sunlight. It was shot at ISO 100, f/8 at 1/400 second - the recommended "sunny 16" exposure (which is what autoexposure gave). Sunny 16 rule In photography, the sunny 16 rule (also known as the sunny rule) is a method of estimating correct daylight exposures without a light meter. (For lunar photography there is a similar rule known as the looney 11 rule.) Apart from the obvious advantage of