The question of whether it's a “golf rangefinder” or a “golf range finder” is not important, but since we noticed that some of you type it as two words and some as one, we were just curious about who was right…
I guess you could say everyone is both right and wrong. It all depends on where you look.
The major brands, Bushnell, Callaway and Leupold, all call them rangefinders. But if you type “rangefinder” into the Merriam-Webster.com, it returns “range finder” with a definition that ignores golf, but is generally applicable. Same thing with Dictionary.com.
On the other hand, if you go to Wikipedia and type in “range finder”, it will send you to the “rangefinder” page and it even mentions golf as one use. The Free Dictionary is the most tolerant of all, as it accepts that either one is correct.
So hey, You're Not Wrong, whatever you typed to get here!