Tilt Series Range Finder Dialog

This dialog box allows you to acquire a series of images at high tilt in order to determine the usable range for a tilt series. After the series is acquired, you can examine the stack of images and use the Tilt Series Range Viewer dialog to pick which angles should be the limiting angles for a tilt series. Your chosen angles will then be imported into the Tilt Series Setup dialog the next time that you open that dialog. There are diverse factors that govern a choice of highest tilt angle, including the quality of images, the proximity of a grid bar, etc. Rather than trying to make this choice for you, this dialog provides flexibility so that can acquire the images needed to make the choice rapidly in a particular situation. The routine that acquires the images does try to detect the highest suitable angle by examining the mean intensity in the central part of the images.

The program will maintain alignment to the position at which it starts. Thus, it will record a lower-magnification reference image at zero tilt before it starts, and then align to this at the end. If you choose to have series done at both positive and negative angles, it will also align to this position between the two series. If you choose the option to use the Warp Up procedure, the program maintains alignment to the same position at higher tilts.

Regular versus Low Dose mode

Separate parameters are stored for low dose and regular imaging modes. In addition, the two modes provide a different choice for the kinds of images to be acquired (see below).

Actions before taking image series

These check boxes select which operations to perform before acquiring the series:

1. 'Refine eucentricity' runs that routine before leaving zero tilt
2. 'Walk up' uses the Walk Up routine to maintain alignment to the starting position; otherwise the program will simply tilt the stage to the starting angle of the series. If this option is selected, the program will also align successive images of the series unless the image shift bcomes too high.
3. 'Autofocus' runs the focusing routine at the starting tilt angle.

Image series angles

Enter the starting and ending angle and increment of the series. Enter positive numbers; the negative of these values are used for a series in the minus direction. The program will stop the series before the ending angle if image intensity falls rapidly between a pair of images.

Directions to sample

Select 'Both' to have a series done on both sides of zero, 'Minus only' to have a series at negative angles only, or 'Plus only' to have a series at positive angles only.

Take image series with

Select the kind of images to be used for the series. In regular mode, the images can be Trial (for speed) or Record (to assess quality), while in Low Dose mode, the images can be View (to give a broader overview), Trial (useful if alignment is being maintained), or Preview (to see the Record area itself).