Sony hdw-730 Operation Manual page 307

Refitting the eyepiece
1
Align the match mark on the eyepiece locking ring with that on the
viewfinder barrel.
2
Align the match mark on the end of the eyepiece with that of the
eyepiece locking ring, then insert the eyepiece into the viewfinder
barrel.
3
Turn the eyepiece locking ring clockwise until its "LOCK"
indication arrow points to the match mark on the viewfinder barrel.
Note
When the eyecup is worn out, replace it with a new one (service part
number 3-723-079-03).
Match mark on the end of eyepiece
Chapter 5 Setting Up the Camcorder
5
5-13