[Asar]

По поводу ЕТТЛ2 -- вряд ли будет "частая недодержка" аж в ступень, если Вы не снимаете постоянно в очень и очень специфических условиях. Да и то.

Например:
...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.

Взято с http://www.bobatkins.com/photography/eosfaq/ettl2.html