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ar345 Program Manual 3 5
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The decision about what pixelsize to choose is slightly more difficult. In general, the fine
st
pixelsize of 0.1mm is more efficient and yields slightly better data. On the other hand, scan
s
take about 10% longer time and images are larger in size than those taken at the sam
e
diameter but in 0.15mm pixelsize mode. So the decision is some kind of compromise.
O
utput format:
Use of "mar345" format is strongly suggested. A mar345 file typically requires 70% less dis
k
space than a standard uncompressed image file. All major protein data processing package
s
support this format.
C
ollect mode:
Use TIME mode unless on synchrotrons.
For indexing crystals, usually 2 images that differ from each other by a movement in
ϕ of 9
0
degrees gives good results. In the case of very small molecules (i.e. cell axes of about 1
0
deg.) you may not get enough spots from 2 images only.
5
.2 Checking Parameters
Before starting a data collection, mar345 makes a consistency check of the input parameter
s.
In most cases the program will tell you if the input parameters really do not make sense.
It
checks wether files can be opened, if there is enough disk space, etc.
5
.3 Errors and Warnings
In case of computer or scanner problems, warning messages will be printed on standar
d
output and in the log file. Very important messages will also be displayed in a special window
.
Problems fall into 3 categories: fatal errors, warnings and notifications. See chapte
r
T
roubleshooting for more details.
5
.4 End of Data Collection
After having finished a data set, mar345 writes a summary into the corresponding dat
a
directory. The summary files come in 2 formats:
− image_root.SUMMARY = plain Ascii text file
− image_root.html = Ascii−file with HTML−formatting instructions.
These files should be printed and archived.