Hi excuse what I'm sure is a simple question. I wanted to capture a long exposure using a 10 stop ND. The clouds weren't moving that fast so I wanted an exposure of at least a minute. Using one of the calculation apps, I knew that I needed the speed to be 1/15 to get to 1 min 10 stops down. My ISO was at L and I was using a middleish aperture. No matter what I did I could not get the exposure right in the viewfinder. The reason for the confusion was that I was sure that I saw a video of someone using a 1/15 shutter speed in bright sunshine and I don't think he was using any filters (prior to applying the 10 stop) to get to that. What am I missing?