Nikon cameras feature a "through the lens" light-metering system as of 2010.
TTL refers to "through the lens" light metering and is featured on all Nikon cameras produced after 1984 at least until 2010. Light metering allows you to achieve correct exposures in different lighting conditions. TTL light meters can be synchronized with external hot lights and flashes.
What TTL Does
TTL metering allows you to measure your exposure settings without using an external light meter. This is particularly useful if the subject is not within reach or covers a very wide area, such as landscapes.
How TTL Works
TTL light metering works by measuring the light that passes through the lens. The metering system also uses the information from your aperture and shutter speed settings to calculate the correct exposure.
Using TTL
The TTL light meter is visible when you look into the view finder. Many models use a plus and minus sign system to indicate overexposure or underexposure, with a circle signifying a correct exposure.
Tags: through lens, correct exposure, light meter, light metering, metering allows, Nikon cameras