I had been walking for around two hours when I heard the sound of water. In the morning I had set out to get shots by the river so the sound of water drew my attention. I cut across a few coffee bushes when I saw the waterfall. I took a number of photos from different spots. I walked another two hours back home, put the mem card in the comp only to find the photos I had taken had a spot bicause of some sensor dust.I almost lost it. Five hours only to have unusable images. I deleted every photo I had taken, cleaned my gear and got back to the spot.