Hi
I have the fujinon converter for mounting B4 lenses on my EX3 - I am not quite happy when making pictures with highlight portions. The chromatic aberation gets very high.
I cannot figure out if it comes from the glass in the converter. I wonder if the MTF converter is better, as it seems not to have a glass inside. Anyone tried a comparison ?

It's going to be from the lens. Don't forget that the EX3 has auto CA correction when using the standard lens. When you use B4 lenses there is no CA correction.