I have been in the search for a new wide-angle lens for my A7II after being dissatisfied with the bridge solution of using my Canon EF 17-40 f4L with an adapter. I recently came across a listing on ebay for this lens and the deal was too good to pass up and about an equal trade to my existing wide-angle setup. Having the 17-40, which I have used on the Canon 6d before my switch to Sony, has given me perspective on which focal lengths I enjoy utilizing in my photography. The Sony FE 28mm f2, which has received almost unanimously favorable reviews, was interesting to me, but I find that 28mm is just not quite wide enough. The other native FE mount lens that is available is the Zeiss Batis 25mm f2. This was an interesting option, but is currently hard to find, expensive, selling for a premium on the used market, and has a relatively large filter sized compared to my lens line up (it has a 67mm filter where my largest filter size is currently 52mm).
What drew me to the 25mm ZM Biogon? I like to think of my A7II as a poor mans Leica and am currently using rangefinder lenses mounted to it. Rangefinder lenses are attractive to me due to their small physical size, solid build quality, and the presence of a focusing scale on the lens. I have the Voigtlander close focus adapter (and extension tubes when necessary), so I already have a solution to the relatively long minimum focus distance of rangefinder lenses. Compared to most rangefinder lenses the Zeiss 25mm has a relatively short minimum focus distance of 0.5 meters. I have noticed with this adapter, closer focusing distances and therefore larger reproduction ratios are easier to obtain with wider focal lengths. Upon look at lens reviews and reviewing images on Flickr I decided that it was worth a try. Also, if I was unsatisfied with the lens I knew I could repost it on ebay for more that what I purchased it for (did I mention the deal was phenomenal for a mint condition lens specimen).
While I do not perform technical tests on my lenses, I do pixel peep when trying new glass and this lens performs quite favorably to other lenses I have shot on the Sony. One of the most apparent differences compared to my Voigtlander 40mm f1.4 and 75mm f1.8 is the color and contrast that the Zeiss lens produces. While I like the Voigtlander lenses, especially the 40mm, there is really no comparison to the Zeiss. I have not noticed any chromatic aberration, even when attempting to introduce it. Sharpness appears excellent and I have a feeling that the new A7RII would be a much better test of this lens than the 24mp sensor in my A7II because this lens is sharp.
To acknowledge the cons of this lens: It is manual focus, requires an adapter (and a helicoid adapter for close focusing), large new purchase price tag, vignetting at large apertures, lacks a Lightroom profile, and f2.8 maximum aperture compared to native f2 options. In most situations flare is well controlled, but can be introduced when pointing the lens at the sun. I have read that there can be a magenta color shift in the corners of adapter wide angle lenses on the Sony system, and I am glad to say that I have not noticed it with this lens, however the performance in the corners does not hold up to the excellent center image quality. There is a dramatic loss of sharpness in the corners even when stopped down to f8.
After my first import I knew I had made the right decision. The files this lens renders are very much to my liking, that is to say they are sharp, contrasty, and offer great subject/background separation. From what I can tell through my research, this lens has not been written about much in conjunction with the A7 series and that surprises me since it is such a great, compact performer.