The Canon Speedlite 420EX is an autozoom flash unit equipped with a wireless sensor for E-TTL wireless autoflash. * E-TTL stands for Evaluative-Through-The-Lens Canon Speedlite 420EX Manual Online: Flash In Full Auto Mode. With the 420EX attached to a Type-A camera set to (Program AE), flash photography will be Ahoh. Attention! The text in this document has been recognized automatically. To view the original document, you can use the "Original mode I have urgent question: if I mount SpeedLight 420EX on 350D, will it work in manual mode firing no pre flash for E-TTL? Read Online canon 420ex manual mode Paperback Open Library. Gо thrоugh Frее Bооkѕ Onlіnе аnd еvеn Dоwnlоаd еBооkѕ fоr Frее оf сhаrgе. in it's "manual mode". Problem is, when using a 550ex as a master and 420ex as wireless slave, the 550ex won't work as master if it's in manual mode.Canon Speedlite 420 EZ Manual Online: manual mode [ttl], Ttl Automatic Mode. Camera Flash Canon Speedlite 420EX Instruction Manual. (56 pages). Find support for your Canon Speedlite 420EX. giving them access to remote camera control and communication functionality of the camera.