I have never seen the 20mm in UK. There was aF3.8 19mm lens sold under various names - Vivitar, Cosina, Sirius were a few of them. It was around about 20 years ago and it was absolute utter rubbish I wonder if this was developed from it? It certainly couldn't be worse. It had a 62mm filter thread and the build quality was good, but the glass - Ugh!