Welcome to Coin Talk. It looks like a plating blister by the letter F Information on plating blisters can be found on error-ref.com http://www.error-ref.com/?s=plating+blisters
@Ed C. You will get more answers if you start a new thread with this question. I'm not a photographer so I can't help. I take photos of my coins in natural light. (Not direct sunlight).