I've tried to do this with layers, but I could never get the camera to zoom in on just the one thing, it always zooms on th whole screen.
P.S. Anticipating that someone may suggest using the Camera plugin, I have to say that I've never been able to install a plugin in Construct. I download it, I place it in the folder, but when I try to run it crashes or simply doesn't acknowledge the plug-ins existence.