Tv files and m files of canon 600D.

Please shoot with the viewfinder. Generally, LCD screen is not used.

Why TV and M files are so dark;

65438 +0. M file is because you set completely wrong exposure parameters.

Number 2.2. The TV file is because the aperture has an upper limit (for example, if you have a 18-55 is lens, the upper limit of 18mm end is 3.5, and the 55 mm end is 5.6).

Using AV files generally does not have this problem.

As for why, it is a long story. You can download this e-book to understand-DLSR digital SLR photography Bible, online in PDF format.

Actually, it's okay to read the instructions or something.

Novices should not aim too high, not to mention that the camera is broken or worse than others.