I'm putting my money on it being a 50mm f/1.8......
The "F--" means that the camera can't set the aperture on the lens. Could be an old lens that isn't capable of having the aperture set by the camera.
That's ok, I take cheques!
Ahh...different fault then...
with the 50mm it's usually because the lens isn't locked on it's smallest aperture, with the 70-300 VR it is caused by a poor connection between the lens mount and the camera body.
Tell her to take the lens off, clean the mounts and refit it. That should cure it. Unfortunately it's a common problem with that combo and will probably reoccur.
The cheque's in the post (one of the three most commonly told lies )
Last time I got the F--- error message, I thought my Nikon was being censored!
Turned out that, if I slightly rotated the lens within some slack, perhaps not supposed to be there, while still mounted, (AF-S Nikkor 18-135mm), the problem quickly disappeared.
I wish that were so with my new error message which won't go away. It simply displays a blinking "Err" message and won't record or display a recorded photo although it "sounds like" it's taking pictures, all in one speed, etc.
Cannot seem to clear it. I fear I might have swerved the camera into the sun. That is the only thing I can conceive could have triggered this!
Common problem when the same lens is left mounted on the camera for long periods, simply removing and refitting the lens solves the issue.
I suspect that the contacts need a bit of exercise.
or maybe to go on the