Background looks like it has three panels of color

I have a model I created and somewhere along the line I ended up with a background that has three sections of color - grey, white, grey.

Has anyone seen something like this, and how do I change it to one color? I’ve searched the different tabs thinking there may have been a preference I changed or a style I created, but have had no luck addressing this issue.

I’m using Sketchup Make 2016

Go to Tools/Advanced Camera Tools and hit Reset Camera.

Thank you, that worked. How did you come to know this? Somewhere in documentation or had you run into this problem yourself?

It’s instantly recognisable to any experienced user. That greying-out of the periphery is similar to the effect yo get when cropping an image in many image editors. It was introduced some years ago as part of the Film & TV extension which not only added these kind of views but also a bunch of new components like spotlights, dollies and other studio equipment.
If you go to the same menu advised by Box, you’ll find a huge array of cameras from 16mm through Vistavision to IMAX…very handy for set designers.