Because your DV is set to "auto focus". When the machine auto-focuses, it must be a little blurred before it can focus. Generally speaking, civilian DVs use the contrast method to measure focus. This method achieves auto-focus by detecting the contour edges of the image. The clearer the outline edge of the image, the greater its brightness gradient, or the greater the contrast between the scene and the background at the edge. On the contrary, in an out-of-focus image, the outline edges are blurred, and the brightness gradient or contrast decreases; the farther out of focus, the lower the contrast. Using this principle, two photoelectric detectors are placed at equal distances before and after the CCD. The image of the photographed object is simultaneously split on the two detectors, and the contrast of the imaging is output respectively. When the absolute value of the contrast output of the two detectors is the smallest, it means that the focused image plane is just in the middle of the two detectors, that is, close to the imaging surface of the CCD, and the focusing is completed. From this we can know that there is a process of focusing. You turn on the machine and shoot immediately. The machine has not adjusted the focus yet, so you just happened to shoot the process of focusing. (Focus - the motor drives the lens to obtain the required focal length). The method is actually very simple. You turn on the machine, aim at your subject, use the T-W lever to adjust the composition of the picture, and confirm that everything is OK before shooting. This problem will naturally be avoided. Another method is for situations where you need to shoot immediately after turning on the camera, such as key scenes in a football match. In this case, you can first put the machine in "manual focus" mode and put the T-W lever in W (widest angle). ) position so that you can basically take a clear picture.