I have 2 of these lens. Its very tiny. I put it in front of a voigtlander 35mm and it covers the sensor of my GH3.
The first one I bought was not bad. You only focus the taking lens. Unfortunately I cracked the lens and I bought another one
2nd looks like shit and unusable. I can't even see an image just a blur. That's how bad it is
I have no idea why because they look almost identical.
And those filters in the front. I don't know what they are for. They make the image blurry.
The only thing I thought it was good for was making the smallest anamorphic possible. When I had them on a GF1 the entire camera could fit in coat pocket. But that's it. Its a novelty thing.