Yup, that's it. The plane taking the photos was something like a Piper Cub and its max speed was just above the F-104's stalling speed. In addition, the F-104's limited visibility meant that very often Joe Walker couldn't see the XB-70's wing and just had to hope he was in the right place.
From what I've read, the crashes in Europe were mostly due to the fact that the F-104 was a high-altitude interceptor, but in Europe it was forced into service as a low-level high-speed attack bomber - the kind of role that had been planned for the TSR-2 - and it was horribly unsuited for it. But Lockheed spread its sheltering slush fund around and none of the politicians died.
In the 90s the Luftwaffe sold off a lot of old F-104 airframes, minus engines and, presumably, armament. A chap a few km from here bought one and kept it in his garden for a few years; then one day it was minus wings and a bit later it was gone. Rather beautiful.
