Focussing doesn't zoom object

Hello!

I'm pressing F on the keyboard to focus on an object in the Scene window.
This works, but it doesn't work as I expected it.
I expected that Unity would zoom in to allow me to inspect the object more clearly.
Instead, Unity sometimes even zooms out so that the object becomes even smaller.

Can anybody tell me how to "fix" this?

Zooming in manually is rather time taking if I have to do it often.
I was hoping that F was my solution.

Thank you very much!