Optical Range of Civil War binoculars or telescopes

Robert Gudmestad's picture


I have a graduate student who is interested in creating a view shed for two forts in Colorado in the 1850s. He is curious to know the optical range of a mid-nineteenth century pair of binoculars (field glasses) or telescope so that he can learn how far a soldier in a fort could see compared to a Native American without such technology. Any estimates or sources where such information might exist would be most appreciated.

Robert Gudmestad

Colorado State University 


Interesting project! Ultimately, it's a very hard question to answer. Whether or not the optics utilized in the forts in question were Signal Corps-issued or private-purchase is the most vexing problem, as binoculars and telescopes of the day varied considerably in magnification power - just as they do today. Depending upon what records survive from the garrison of either fort (I would be prowling the garrison or command QM records at NARA for any data on optics purchases or issuance), it's tough to know just what the garrison was working with. That said, here's a 2002 article on wartime Signal Corps telescopes that may be of some use as a starting point:


I have seen any number of nautical/maritime collapsing telescopes bearing wartime inscriptions by volunteer infantry officers, but alas these varied markedly by model in magnification power as well. Certainly it is possible to derive a ballpark average estimate, though. Best of luck to your student in pursuing such a compelling and important question!

Eric M. Burke, Ph.D.
U.S. Army Combat Studies Institute - Army University Press