[HermanLee]

You might want to test the same subject for both your A50 and FA43 Ltd to see the difference.

I have the F 50/1.4 and FA 43/1.9 Ltd. Comparing both, there are times when you don't see the difference. But in some cases, I like the rendering from FA43 better. In less than ideal light, I don't see that much difference. But in ideal light, or very good light condition, the FA 43 gives me a much better (some people call it 3D rendering) picture that makes me wonder too.