Although Old Faithful is pretty reliable the lighting is not always what you are hoping for. I sat with my daughter and waited for Old Faithful to erupt with the sky completely clouded over threatening to rain and totally flat light. I decided to put on a neutral density filter to allow for a longer exposure time to see if the water would look cooler “in motion”. Then to my surprise a beam of light shone through the clouds onto the geyser and lighted it just at the right time.