I think im still not understanding how my flash works
 

So I was taking a photo of my daughter a few minutes ago. I used manual, pretty high ISO and I used manual flash at 1/128 power. On my preview it looked too bright for my taste. Then I changed the flash to E-TTL and kept the same shutter, aperture and ISO and the result was good. How come the ETTL can set the flash power lower than 1/128 power but I cant do it manually? 1/128 is as low I can go.</p>
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