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findresolution: Diffraction limits for different measurement times

The "findresolution" program calculates a good suggestion for the measurement time needed per degree of rotation to get a dataset with "observed" reflections upto a specific diffraction angle.

Usage

The program is invoked by the command line:

  findresolution [options] <imagefilenames>

Different image file types are recognized from their names.

The only option that is recognized is "gui", which will turn the program into a "GUI" (i.e. it will pop up its results in a window instead of on the terminal screen). This option is used from the supergui program.

The output produced by the findresolution program consists of some text that can give you a hint on measurement time needed to get a reasonable dataset for the crystal. The program can e.g. be run on the images that were used to find the unit cell.

If available, the program will use distortion correction (see programs makedistor and makedetalign), but this is not strictly necessary for proper functioning.

Example

For a test ammonium bitartrate crystal, the following data were obtained:

s01f001.kcd;  58 peaks found, 399 trials, 1.81 seconds
s01f002.kcd;  54 peaks found, 379 trials, 1.95 seconds
s01f003.kcd;  62 peaks found, 429 trials, 2.08 seconds
s01f004.kcd;  65 peaks found, 455 trials, 2.17 seconds
s01f005.kcd;  53 peaks found, 395 trials, 1.99 seconds
s01f006.kcd;  62 peaks found, 397 trials, 2.03 seconds
s01f007.kcd;  54 peaks found, 424 trials, 2.00 seconds
s01f008.kcd;  64 peaks found, 421 trials, 2.09 seconds
s01f009.kcd;  55 peaks found, 460 trials, 2.09 seconds

RESULTS
-------
Correlation coefficient= -0.986 for 10 points.
The input images were taken at 10.0 seconds per degree.
At this exposure time, diffraction might be visible upto theta=35.3

   Exposure time         Expect theta max       Resolution
(seconds per degree)       (degrees)            (Angstrom)
       20.0              37.7 +/-   2.2             0.58
       60.0              41.5 +/-   2.3             0.54
      120.0              44.0 +/-   2.4             0.51
      600.0              50.4 +/-   2.8             0.46

Overflows could appear above 6 seconds per degree.

Since this crystal diffracts very well, data upto almost 40 degrees (far more than the normal 27.5 degree sphere) is expected to be usable even at a relatively short exposure time of 2*10 seconds per degree.

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