It’s still difficult to believe that our friend Galen Rowell and his wife Barbara are gone, since his work continues to live on in so many books, magazines, calendars and in our mind’s eye, and he still is such a presence in the lives of his friends, family and photographers everywhere. Galen wrote this column for Outdoor Photographer in 1992 when not many photographers were familiar with Graduated Neutral Density filters, and it provides an interesting perspective and insight into …