Please advise the master who knows photography.

The landlord can go to hummingbirds and oak trees, which is milder. Friends there will be happy to help you! You can buy a lens pen for the lens, and just blow off the dust with air. If it can't be blown off, you can gently brush it off with a soft brush. If there is oil, you can breathe into the lens, then roll it up with a paper towel like soul mate and tear it from the middle. Rub lightly with a rough surface, and there will be some fibers at this time. You can get it off with a brush and blowing, don't use force.

What you said seems to be the problem of shutter lag ~ It depends on the structure of the camera itself, and you can't adjust it, including the SLR. Please be familiar with the performance of the camera and calculate the advance to shoot:) For the adjustment of the aperture shutter, I personally suggest that you use the A file to adjust the shutter speed according to the aperture size, so that there is room for controlling the depth of field. And adjust the exposure compensation according to different metering modes:)