The main reason I bought the Sony NEX 7 was to use with my Leica M kit, even though many reviews that said the NEX 7 sensor has a serious flaw that makes it unsuitable for use with wide angle rangefinder lenses. The NEX 7 sensor has a layer of micro-lenses, these micro-lenses focus the light hitting them from the lens onto the photo-receptor sites of the sensor. On the NEX 7 they’re built with SLR type lenses in mind that sit much farther from the sensor than rangefinder lenses, the light coming from SLR type lenses striking the sensor at nearer to perpendicular angles. Rangefinder lenses, especially wide angle ones, have rear elements that extend much closer to the sensor, causing the light they focus to hit the sensor at much more oblique angles the further they strike from the center. The micro lenses of the NEX 7 sensor can’t seem to handle light hitting them at such extreme angles which leads to color shifting and lowered sharpness at the edges and corners. I won’t dispute this makes the NEX 7 less than optimal when paired with such lenses, the question is: “Is less than optimal still good enough to take good pictures?” The first lens I’ll be taking a look at with this in mind is one of my favourites, the Voigtlander 15mm f4.5 Heliar.
I’ve been using this lens with great success on my Leica film cameras for years, later it became one of my most used lenses on the Sony NEX 3 as well. On the NEX 3 it performed very well, with very good corner sharpness and color fidelity. I was kind of worried when I heard it didn’t fare so well on the NEX 7. After trying it out for a few weeks, I admit, the NEX 7 definitely had an issue with wide angle rangefinder lenses. I do notice some loss of sharpness and magenta color cast in the corners with the Voigtlander 15mm, especially wide open, by f8 it’s much better.
If you’re a landscape photographer who needs perfect sharpness edge to edge or just happen to like looking at pictures of brick walls at 100% magnification, this may not be the lens for you. On the other hand, if you already have one, it’s definitely worth the price of an adapter to be able to use it on the NEX 7. It’s still wonderfully sharp over the majority of the frame on the NEX and has very little barrel distortion. It’s nice and small, making the camera nearly pocketable and is wonderful for street photography being roughly a 24mm lens on the NEX 7.