there are two settings viewport focal length (35, in your case) and camera focal length (30.72 in your case), 35 would be default.
on your picture i cant realy see a problem, you just have zoomed out while beeing inside the camera so you se the fisheye-distortion of your camera around the real sensor area. if thats the problem just zoom in.
Your render should look good with 30.72 focal length. If you want ist exacly as in Viewport put it to 35 in Camera-Lens menue.
but maby im missing something?