i have already used Canon speedlite...
the problem is only a very small area is in focus.
eg 2. i take snap on my pen. the point that i manual focus on(exmaple the cap), will be sharp, but further abit, like connection between cap and pen body will start to be blurred..
even if i increase my shutter speed to 1/200, f1.8 iso 100, it is still the same
T_T
try f2, if not f2.8 will give u a deeper dop