Everyone said to me, wide angle converter on mft lenses producing bad picture quality.
Here is my first test with a panasonic 20mm/1.7 lens and a wide angle converter which I have bought for 29€
(Second Hand) at amazon.
With the converter I got a fast 13 mft (26mmKB) wide angle lens and a macro lens with a very good depth of field.
In my opinion the picture quality is not so bad and I'm happy because it's a very cheap solution.