Night time reflection in pool

This was an early test of capturing a picture in the dark. This was at about 12:30 AM with no moon. The biggest error I later realized was that I had auto focus on. Also, IS was on. While I made the adjustments in manual mode, with auto focus on, nothing is really clear or sharp. The F was like 41 and ISO 25,000 and Time was 1/4000. Again, this was a first attempt to capture an image in the dark with the Canon EOA R5 with a 15-35 lens.