the last high-end FD-mount manual-focus camera, the T90, launched in 1986. This was the first Canon camera with through-the-lens (TTL) flash metering, although other brands had been metering that way for some time. It also introduced the A-TTL (Advanced TTL) system for better flash exposure in program mode, using infrared preflashes to gauge subject distance. This system was carried over into the early EOS cameras wholesale. A-TTL largely fell out of favor, and was replaced by E-TTL (Evaluative TTL). This used a pre-flash for advanced metering, and used the autofocus system to judge where the main subject was for more accurate exposure. E-TTL II, which was an enhancement in the camera's firmware only, replaced E-TTL from 2004. Canon Speedlite-brand flashes have evolved alongside the cameras. They are capable of wired and wireless multi-flash setups, the latter using visible or infrared pulses to synchronise. Later models, including RT in their model name, can also communicate via radio links, where up to 16 units can make up a network. Canon also produces Speedlite accessories, including the OC-E3 Off-Camera Shoe Cord, which can be used to hand-hold the flash while allowing the camera to control it through the cord. The Off-Camera Shoe Cord is popular among portrait photographers who need to have more control over lighting than a camera mounted flash can offer. EOS cameras As of 2017, Canon has released no fewer than 70 EOS SLR and DSLR camera models, starting with the introduction of the EOS 650 in 1987. In the 1990s, Canon worked with Kodak to produce digital camera bodies, starting with the EOS DCS 3 in 1995. The first digital EOS SLR camera wholly designed and manufactured by Canon was the EOS D30, released in 2000. Canon sold two EOS cameras designed to use the APS film format, the EOS IX and the EOS IX Lite. Canon also sold a manual-focus camera, the Canon EF-M, which used the same EF lens mount as the EOS cameras. It came with all the automatic and manual exposure functions but lacked autofocus. It came equipped with a split-screen/microprism focusing screen for precise manual focusing. Eye-controlled focusing Through the tracking of eyeball movements, EOS cameras equipped with eye-controlled focusing (ECF) (some identifiable by the suffix E) were able to select the desired autofocus point in the scene, based on where the user was looking in the viewfinder frame. ECF was especially useful in