Tilt Series Back Up Dialog
This dialog box allows you to back up in the tilt series, assess the alignment or quality of images at previous tilts, and resume at a selected tilt angle. When you do that, new images will be taken at each tilt and used to overwrite the existing images until you reach the place that you backed up from. The dialog box presents a selection of tilts, listed by their Z values in the file and by their tilt angles. Select one and push the GO button to back up to that tilt.
When you select an angle, the program will tilt back to that angle, compensating for backlash, read in the stored image for that tilt angle and place it in buffer A, and read in the stored image for the previous tilt angle and place it in buffer D (the autoalign buffer). If you resume from that point, the program will start with tracking and focusing at the new tilt angle, aligning images to the reference from the previous angle. If you are montaging, the program will recompose the center image for the selected angle and for the previous tilt.
If you tilt back too far, you can open this dialog box again and tilt forward again. You can only tilt forward to the last angle that was finished, not necessarily to the angle at which you stopped.
If you are in low dose mode, the program maintains a stash of tracking reference images which it can access to set up buffers appropriately when backing up. Specifically, it will place the stored image from the previous tilt in D and one of the tracking reference images in E. You can then autoalign either Trial or Record images at the new tilt angle. Your choice of angles to back up to may be constrained because of the limited number of tracking references available. When doing dose-symmetric tilt series, there are four reference buffers: D and E for the references when tilting in the negative direction, and F and G for the Record and tracking references when tilting the positive direction. The program will restore references all of these buffers when backing up. Autoalign will align a new image to the appropriate buffer, and the Align To button will be labeled accordingly.
If you are working at a high magnification and need low mag tracking, you may have to get the specimen aligned manually after backing up, since there is not guaranteed to be an appropriate low mag reference in the second autoalign buffer.