I'm certainly not sure but I figured it was close enough that it might be worth a shot, It's likely the company has changed much and / or been aquired by another company since the 60's but who knows, there is just so little information available.
This is what the blue book says about hopf
"HOPF
Instruments previously made in Germany from the late 1950s through the mid-1980s.
The Hopf name was established back in 1669, and lasted through the mid-1980s. The company produced a wide range of good quality solid body, semi-hollow, and archtop guitars from the late 1950s on. While some of the designs do bear an American design influence, the liberal use of local woods (such as beech, sycamore, or European pine) and certain departures from conventional styling give them an individual identity. Hopf produced electric guitars through the 1970s, and has focused on classical guitars since. In 2006, Eastwood Guitars reissued the Hopf Saturn 63 with a few minor improvements. Source: Tony Bacon, The Ultimate Guitar Book."
The price of an Eastwood Reissue Saturn 63 is listed at $879 just for a point of reference, they are no longer available new.
http://www.eastwoodguitars.com/saturn-63-sunburst/"In 1992, it (vintage saturn 63) was featured with Robert Smith in The CURE video, FRIDAY I'M IN LOVE."
So that is probably the most famous use of a Hopf Guitar in pop music. You can see the Hopf pretty well throughout the video starting around :35 seconds on the left side.
Here is a demo video of the Saturn 63 just for fun
and another of a Hopf Telestar