I've had a number of submissions where people have provided an image shot in portrait (vertical) framing. Please keep in mind that only landscape shots (horizontal position) can possibly qualify for full page use. The vertical shots can be used still, though... but for one of the other smaller positions.
So, if you are taking pictures specifically for this, please keep your camera horizontal!
For those that already submitted a vertical image, if I think I see potential for a full page use, I'll contact you about a "reshoot".
Thanks,
-Alex