Kind from the camera.

How to adjust a kind from the camera?

I don’t get your question. Could you elaborate further what you’re trying to do?

I want to see all chain in a camera.

It is necessary, that this model would be visible in a window of the camera.

Well, you could either…
scale down the chain (which seems to be enormously large, considered 1 Blender Unit = 1 m) or

change the camera parameters (reduce the focal length or increase sensor size) or

move the camera back. When in Camera view, this is easiest done by selecting the camera, hitting “G”, pressing the middle mouse button and pulling the mouse towards you.