Just got myself this cheap new flash to start off into flash photography..!
I have a FM2n and a GF670 so TTL was a no go.. Also, I wanted to understand what the hell is going on before I have some auto-calculator figure things out for me.

The graph on the backside seems straightforward enough: If I use asa 100 to photograph something at 3.6m/12ft use aperture f/5.6. Things closer become overexposed, things farther become underexposed. Fair enough.
But that's considering that there is no light in the environment? Does this work during daytime fill as well as nighttime no light?
The flashes front side has what seems to be a little lens.. does that have any influence?

I'm gonna play around with it this weekend but I just wanted to know if I'm about to muck everything up.. Am I on the right track?