Exposure is a factor to take into account when working with light as all photographers have to do. hand held light meters can come in handy when you need to accurately measure light. the TTL (through the lens) meter can be tricked by light types and light condition and the tone and shades of the item being photographed. so you have to tell the meter which light to look for and measure. the TTL meter cannot “see” flash. Handheld meter can read available light so what is the current light status say daylight or lamps (artificial lights) as well as electronically flash, you have to set the correct mode according to the type of lighting being used.
There are two ways of measuring light by the ‘incident’ light reading and ‘reflected’ light reading.
in a reflected light reading the light hits the subject being photographed and the reflected light is measured.a light meter without diffuser is pointed at the subject and measures light being reflected back towards the camera. this method can be affected by the tone f the object. e.g a white surface will reflect more light than a black one, causing the meter to give different reading even though the light source remains the same.
in an incident light reading the light meter with a diffuser is placed in front of subject, pointing toward the camera. because it is only measuring the light direct from the source the meter gives an averaged reading which is often more reliable both in and out of the studio.
after taking a light reading transfer the setting – aperture (f number) – to your camera, and also check that the camera’s ISO is the same as that on the meter. light travels in straight lines, when it strikes an object it is reflected. also remembering that light source affects the appearance of your photograph is important also taking into account that background and surroundings will affect how light behaves. different kinds of light behave in certain ways because light outside varies with weather, season, time etc., whereas studio lights are controllable. in order to truly understand light you need to experiment.