Procedure of recording a tilt series

1. Record an image with a large field at zero tilt. CJ and JM had the experience that it is very easy to ``lose'' the area of interest when going from zero to large angles.
2. Close valve V9i.
3. Move the z motor upstream by around 2 mm.
4. Move to the most clockwise position that is still ``safe''. Safe means that you are confident that the specimen holder will not touch the OSA.
   Example: if the working distance is on the order of 1.5 mm, and the area of interest is roughly on the axis of rotation, an angle of $-50^{\circ}$ (i.e. $50^{\circ}$ clockwise rotation) is safe when using the Stony Brook Fischione holder.
   Moving clockwise is suggested because this allows you to see the OSA above the specimen holder when looking through the telescope. When moving counterclockwise, the specimen holder obstructs the OSA.
5. Keep in mind that the worm drive may have a backlash, therefore it is good to always approach the imaging position from the same direction.
6. Lift the holder off the socket by gently pulling on the flange which holds the springs around the bellows.
7. Rotate the airlock by turning the worm drive.
8. Set the specimen holder back into the socket on the scanning stage.
9. Move the z motor back part of the way. For the last few 100 micron, observe the OSA and the specimen holder through the telescope. The shadow of the OSA on the specimen should give you a feeling for the distance between OSA and specimen holder.
10. Refocus, recenter your specimen and image.