The term refers generally to control the amount of flash light emitted by the measuring light when returning to the same flash sensor through the lens. In TTL flash metering it occurs after the shutter has opened -the sensors record the amount of light created flash back to the camera through the lens and flash ( turns off automatically "cooling" ) when you haveproduced an adequate amount of light.

A Gigabit Interface Converter (GBIC, for short) is a module that is available in many forms, depending on the model and manufacturer of the brand. Each has the same function which is to increase the speed of data transfer through a network. Companies that need to transfer large amounts of data quickly, sometimes using a GBIC module for greater control and profitability. A GBIC moduleIt allows users to reconfigure fiber links, set costs of adapting the receptor and link distances network topologies and requirements established. Used in an optical fiber or Ethernet system, the GBIC modules can update, change or connect without turning off the computer. This flexibility eliminates the need to replace the entire network system together.

SFP transceiver, English small form-factor pluggable transceiver (in Spanish transceiver small form factor pluggable) or, in English, SFP transceiver and abbreviated known as SFP, it is a compact, hot-pluggable transceiver used for data communications applications and telecommunications. They are designed to support SONET, Fibre Channel, Gigabit Ethernet and other common standardsications.

Gbps (Gb/s, Gbit/s) is the speed with which information is transmitted. It is normally used to measure the speed information in the ADSL/fiber addresses transmitted.

• 1 Gb/s is equivalent to 1,000,000,000 b/s.
• 1 Gb/s is equivalent to 1000000 kb/s.
• 1Gb/s equals 1000 Mb/s.