Just had a day of testing with the brand-new, improved 15mm prime from Voigtländer. They call it the 'Aspherical III'. This lens is the improved version of the older 'Aspherical II', which had a lot of problems on a full-frame camera's like the A7: heavy vignetting, and lack of detail and a lot of chromatic aberration in the corners. So I was very curious about how this lens would perform.
The results are absolutely positive: there is still some vignetting, but nothing that cannot be easily corrected in PS or Lightroom. But the good news is that sharpness is excellent, even in the corners of the image, and at wide open aperture (4.5), and also the colorcast problem has been solved almost entirely.
Moreover, this little lens is very well built and finished and very compact. A treat on the A7, even for long walks. It can hold a filter in its thread, but the lens hood is a fixed one.
The in-body stabiliation of the A7 mk II works flawlessly, although at this focal lengt that is not such a big deal.
This could very well become my favorite lens for my A7 mk II