When I first started using it, it was a free bonus for purchasing the whale, but now it always costs the same as a regular one. A lot of people have written articles about curved autofocus. In this situation, we can't forget about the material. You can verify this by installing a depth of field calculator on your phone, such as DoF Calc. When shooting an item from a distance of two meters, the sharpest field you will have is only twenty centimeters wide. That is, only 10 centimeters in either direction can be measured out from the point of sharpness. If you or the subject move more than 10 centimeters between the time the camera is focused and the time you press the shutter button, the picture will be fuzzy even though it was taken properly. In addition, this is not a lens obstruction, but rather a feature that you should be aware of. So, it will not be able to take a picture of a person swinging with an aperture of 1.8 while the camera is set to its regular autofocus setting (non-tracking). To clarify, photographing from a distance of two meters with interesting lenses in order to achieve FX is not feasible. For instance, the depth of field from two meters away with an 85mm lens set to f/1.2 is only four centimeters! In other words, if you concentrate on the very tip of the nose, then the pigment on the cheeks will already be uneven. And if you swung it even a little bit, the whole frame is often going to be in soap. And what, do you think it's a faulty lens?