One method of calibrating your data files is to visually adjust the calibration parameters and compare the results with positions calculated using a standard Bruker calibration file. These files are actually quite simple, and you can create one yourself using most standard text editors with the provided file (agbe.std) as a template. The first line is a title, and the each remaining line consists of a d-spacing (in angstroms) and an intensity (which isn't used for anything). Note however that this is one place where the number format is not locale-dependent; the d-spacings should all use the American format. That is, a d-spacing that is a little over 45 Angstroms should be written as 45.3 rather than 45,3.
To begin, click on "Start" under "Show Bragg Positions from File". This will open a dialog box which will allow you to navigate through the file system and find the calibration file you want. It should have a .std extension, although this may be invisible under Windows. Select the file you want to use and click Open. A set of circles should appear on the data image.
Now click "Enter" under Enter Instrument Parameters by Hand, and adjust the center, range, and other parameters until the calculated rings lie on top of the measured rings and adjust the center, range, and other parameters until the calculated rings lie on top of the measured rings and the Bragg rings are as circular as possible.
Note: This will fail if you are not using a calibration file appropriate for the data set you are using. For example, if the largest d-spacing of the calibration sample chosen is still smaller than the minimum d-spacing accessible for the camera length of your apparatus, no rings will appear on your image. Likewise, if the d-spacings are too small, you will get a large number of useless rings at very small radius. Also, you want to make sure that you have set the color scale such that the diffraction rings of interest are actually visible before starting the calibration process.
Adust the center positions, detector tilt, azimuth, and Q-range until the calculated circles lie on top of the measured Bragg rings and the Bragg rings are as circular as possible
Important: Remember to click on the Done button when finished. Otherwise, if you click on the image again (even by accident) you may mess up your plot or cause confusion in other parts of the program.