Header Image on Static Front Page

Hello,
I really like this theme, and it is working perfectly for my project. The only issue I have run into is when I set the main page as a static. When I do that and upload and image in the header the image size seems to be off. I am trying to use an image that is around 1200px X 400px but the image seems to zoom in to the center when I do this and gets very grainy cutting off the sides. If I leave the height at 800px this does not happen, but it pushes my content to the bottom of the page. I have also tried uploading the image at the correct size as well as using the crop tool, but it seems to do the same thing for both.
Thanks for a great theme and any help you might be able to provide.