Try cyan, it shows up better, allowing you to change focus far and near easier with your eyes. Red will cause no end to eye problems with far near focusing.
Mike,Why don't you run a simple blur tool on that ring to smooth up the edges. Unless you are using Windows Paint. If so, you can get "Paint.net" freeware which has blur tools. It's what I made the Historic pack with. You might want to increase the width of the cyan ring unless you run the game with the default FOV and nothing increased 100 or above.http://www.getpaint.net/download.html