After briefly studying this lens at The Photography Show, I knew I would buy one but they were in very short supply. Carmarthen were the first to have stock without pre-order. I am not disapppointed, and it's much better than the 10mm Cosina-made Voigtlander I have used since 2016 - AF, and much faster, and absolutely no optical penalty in fact better CA control (or maybe better built-in/Adobe lens profile). Tiny bit less wide, maybe it's 10.2mm and the V is 10.1mm... all these things are allowed a degree of tolerance in description, Leica 50mms were actually 51.6mm for decades. Why 10mm? Well, in professional work it may not be ideal for interiors without some cropping, but square crops (40MP on Sony 61MP sensor) look great without visible exaggeration of space. And there's one thing 10mm does which 12mm or 14mm or 17mm does not. It gets in big sky. You can't 'zoom with your feet' to get more sky in! But 10mm gets you 130° of sky and it's the only way apart from multishot stitching to get there. Even with filters on this lens, 77mm thread and can use a 100mm W/A filter system holder - just. But I prefer to work without using filter systems as Adobe's latest software, and the recovery potential of ISO 100 shots exposed for the bright sky, make them redundant.