Review on Tamron A16NII 17 50Mm Aspherical International by Mateusz Komorowski ᠌

When I tested these three lenses for front and back focus on a target that is often found on the internet, I discovered that the autofocus function worked in some unusual way on all three lenses, despite coming from three separate batches. I'll explain the circumstances under which I made the observation below. Nikon D7000, aim 50-60 cm. The aperture was set to its widest possible opening, and the focal length was set to 50. I bring an object in the distance out of focus, then I center my attention on the middle of the target, and then I fire. Everything turns out the way it should if the lens is normal and does not have back focus. We usually always obtain a steady back focus ranging from one to three centimeters when we first knock down the focus on a nearby object, for instance by placing my palm in front of the lens, and then I concentrate back on the target. If the lens also has rear focus, then the numbers are an even greater cause for concern. The same thing happens when viewed from a wide angle. I assumed it might be the camera itself, so I brought another D7000 with me, but the results were the same. It's possible that this behavior has some kind of rationale behind it, but I was unable to identify it.