Commercial photographer R.F. Turnbull was based in New York and active from the 1890’s-1910’s. (1.)  He seemed to specialize in outdoor views, as evidenced by his work that can be found printed as colorized postcards by the H. Hagemeister Company of New York. These early 20th century views include the New York Speedway, a winter landscape scene in Bronx Park, the Bronx River in winter, and the Board Walk in Asbury Park, New Jersey. Around the time this 1899 landscape study was taken, a color postcard showing the Mohonk Lake Hotel in Ulster county, New York State was copyrighted in 1900 and produced as a postcard. (2.)

Various backstamp citations on period photographs held in the Metropolitan Museum of Art as well as the New York Public library from this era additionally state various addresses for Turnbull:

R.F. Turnbull, photographer. Photographs for publication. 1064 Forest Ave., New York. (NYPL & Metropolitan)
R.F. TURNBULL, // PHOTOGRAPHER, // PHOTOGRAPHS FOR PUBLICATION. // 1206 EAST 167TH STREET, NEW YORK (Metropolitan)
R.F. Turnbull, // Photographer, // R.F. Turnbull, // Photographer, // 98 Bellevue Ave. // Winthrop, – – MASS.  (Metropolitan)

1. description assigned: R. F. Turnbull  (American, active 1890s–10s): Metropolitan Museum of Art: New York: website accessed 2012
2. identified Turnbull postcard for sale on EBAY website: April, 2012. Unknown publisher.