420 EX manual control posibility

I have a chance to get a cheap 420 EX as a slave unit. Right now I am using the 580 as master, and the 430 as slave. I need your help to find out if I could control the 420 manually from the 580.

Let me explain: I know I can not manually set the power on the 420 itself. But, one way I could use my 2 speedlites is to put the slave 430 in ETTL, turn "Ratio On" on the master 580, then hit the "Mode" button to put the 580 on manual mode. From there, I could set the master and slave groups' power output individually. Not RATIO like 3:1, but actual fractions of the flash power--1/4, 1/8+0.3 ect. All those adjustments are made on the 580, I don't have to touch the 430.

So that got me thinking, would that work on the 420 also?

No, the 420EX will not work in manual mode whether by itself or controlled by a master, unfortunately.

The reason the 430EX can be controlled that way by a master is because it can do manual mode on its own. The 420EX can not.

Thx Leo. I had a 420 before, but never tested that way.