Many years ago I corresponded briefly with RHK and ordered a print of that iconic photo of his that appeared as a two-page spread in the famous October 1969 issue of TRAINS: Extra 478 North on the Farmington Branch, July 1941. DPM labeled the photo and the brief text accompanying it "the wide, wide world of narrow gauge." It made an indelible impression on me (and, I bet, many others).
Here's to the memory of RHK and his superb ability to create images that remain crystal clear fifty, sixty, seventy years later.