Realistic Cameras

I'm currently looking into making a somewhat more realistic camera to use in unity. Right now to zoom you either move the camera or change the FoV. This is an issue because I'm trying to replicate a Scope in more of a simulation manner. I need an more exact 2x-10x type zoom that holds a the same FoV at different distances.
I don't like the idea of changing FoV and I can't get an accurate "times" zoom with it. Also just moving the camera adds the complication that you might see through/past objects that are in front of you.
Any ideas on what the best way to tackle is issue would be? Hoping I can avoid writing a whole custom camera.