Why is the picture quality of Canon 500D gray?

Most of Canon's SLR cameras are a little gray in color, so the contrast is low, but at the same time, the details of the picture are preserved as much as possible.

You can adjust the color later, but the details are gone when shooting, and there is no software to adjust later.

Therefore, if you don't play SLR or produce RAW films in the later stage, it is better to use the JPG color of the card machine to be brighter.

As for your second question, it is clear in the tutorial that the shutter time is faster than the reciprocal of the focal length of the lens. For example, when shooting with a fixed focus of 50mm, the shutter speed should be at least 1/50 seconds to ensure a clearer picture. Because 500D is half a picture, it takes at least1100 seconds to be on the safe side, but if you pursue shooting,

The sharpness of the ferrule itself is not high, and the lens that can achieve sharpness under large aperture is the bull's head of 35L 135L 70-200/4IS.

The maximum opening of the pullover is near F8 -F 10. Narrowing the aperture should be able to meet your satisfactory standard, otherwise you will have to turn to PS for later solution.