E-TTL II, The new Canon EOS E-TTL II flash system and compatible lenses

E-TTL II, The new Canon EOS E-TTL II flash system and compatible lenses: "The Canon EOS E-TTL II Flash System

With the announcement of the Canon EOS 1D mark II 8MP DSLR and the 35mm film based Elan 7N/7NE, Canon have introduced a new flash system called 'E-TTL II'.

Basically this is a new flash algorithm, similar to the existing E-TTL, but designed to give better results under difficult situations, such as when there is a very bright reflection from a small object in the scene.

Just like E-TTL there is a preflash which is used, along with ambient light metering, to determine the flash exposure using the center 17 metering zones. Zones which differ greatly in brightness are given less weight since they are likely to be reflections from small, highly reflective, objects.

With lenses which return distance information, this may also be taken into account by the flash algorithm, but the point to note here is that the E-TTL II system works with ALL Canon lenses, it's just that those which return distance information provide an additional parameter for flash calculation. Even without distance information ETTL II should provide better results in difficult situations. So all your lenses will work just fine with E-TTL II, it's just that under some circumstances, E-TTL II compatible lenses might give slightly better exposure when using shoe mounted on-camera direct flash.

In general, if a lens uses a ring type USM motor, it returns distance information and so is E-TTL II compatible. Not all USM lenses use ring USM motors. Those which do not offer full time manual focus ( e.g. the Canon EF75-300/4-5.6 USM), do not return distance information. Lenses using AFM (arc form motors) do not return distance information (e.g. 50/1.8, 24/2.8).

Notable lenses which you might think would return distance info but don't are the 50/1.4 USM and the 85/1.2L USM. The tilt-shift (T/S) lenses are manual focus, and so of course do not supply distance information.

Non-current"