Problems of Canon 17-40mm red circle lens photography.

1. This is the so-called "out of focus" phenomenon; Ordinary lenses are generally not easy to find, and this problem will occur when a good camera is equipped with a good lens;

2. 17-40 is most suitable for portrait shooting, and 17 is very distorted; When the 17 terminal is used, the general distance is about 1-2 meters. If it is closer, the aperture should be adjusted to 5.6 or 6.5. The smaller the distance, the shallower the depth of field, the more out of focus, and the easier it is to be empty.

3.40 end 3-5 meters, if the camera and lens are not out of focus 1 meter, there is no problem;

You should take a closer look at the photos you took to see if the imaginary direction is forward or backward (out of focus). If this deviation is in the same direction, you can adjust the "autofocus fine adjustment" of cameras of 50D, 7D and above. Please see my space for specific methods.