Hope you are enjoying S5 and exploring it's everything. While doing the same, I faced some complexity especially in Selective focus option. It's a really good option to have the same in mobile camera. I tried to shot some pictures through Selective focus option. But it seems to me that it's not guaranteed that picture will be shot as expected. For instance, I shot a picture of mine friend. I noticed when there's multiple object in viewfinder, picture not captured in Selective focus mode (I also tapped to focus and also locked the focus). Picture will be captured but a message will be appear mentioning that "Picture saved but unable to apply focus contrast effect, Subject not detected.". After having lots of try I managed to shot only 3 pictures in selective focus mode.
I might be doing wrong that's why picture is not capturing in selective focus mode. If anyone knows how to successfully capture shot in selective focus, please let me know. I am really interested to know how to use it.