Why can digital cameras zoom 4-5 times at will, while SLR's 50-200 lens is only 4 times?

Ordinary digital cameras, because they can't change lenses, have a larger zoom factor, that is, they are more practical from wide-angle coverage to medium focus or even telephoto. But other things being equal, the lens with large zoom ratio is generally not as good as the lens with small zoom. The so-called fish and bear's paw can't have both, and the zoom is practical and small. SLR cameras can change lenses, so there are many lenses designed for different occasions. For example: 18-200, 18-270, etc. They are all large zoom, focusing on meeting the requirements of wide-angle to telephoto with one lens, which is simple and light when traveling; Ordinary zoom lenses: 18-55, 50-200, etc. Suitable for different occasions with different focal lengths; 50, 85, 135, 300 and other fixed-focus lenses can't zoom, but they can get good imaging results. The so-called fixed focus has no weakness, that's all.

Can you get a clear image of 200 meters?

You should know: generally no jitter, accurate focus and normal exposure. If the subject is within the depth of field, the imaging will be clear. It has nothing to do with distance.

When you say clear, you mean the magnification of imaging with different focal lengths. For example, when the focal length is 50mm and the focal length is 200mm, the viewing angle (imaging range) obtained at 200mm is less than 50mm, but the local resolution is high.

It's like seeing with your eyes and a magnifying glass. Everything is very clear, but the scope of the magnifying glass is smaller, but what you see is enlarged and you can see more details.

I don't know if you understand this, but I hope I can help you.