Some problems of novice canon 650D. I don't know why I can't press the shutter in the dark.

1: The main reason why you can't press the shutter in dark environment is that you can't focus in low light. You can turn on the flash to assist focusing, or use MF to focus manually.

2. This question is broad. When using AV files, just ensure that the shutter is above the safety shutter, and TV files can be decided according to the shooting purpose.

This is rather broad, and there is no specific reference, so it is impossible to answer accurately.

Through questions 2 and 3, we can know that you lack the basic knowledge of photography, so you should find more articles on the Internet to learn. And then master it through personal practice.

There are many articles in my space, and I can find some interesting things by classification. For reference.