There is a bug in the latest imosflm (v0.5.2) which prevents the
correct direct beam coordinates being read from the image header for
Mar 3x3 tiled CCDs (225mm square, as installed on ID23-1 and BM14 at
ESRF for example). This is the ONLY detector affected by this bug.
When the program cannot read the direct beam position, it sets it to
the physical centre of the detector. This generates a warning message
(an exclamation mark will appear in the bottom right corner of the
GUI, click on the exclamation mark to list the warning). The direct
beam coordinates will be set to 112.43, 112.43 (or values very close
to this).
The physical centre of the image can be several mm from the true
direct beam position and this will almost certainly cause the indexing
to fail !
The fix is very simple, and requires a change to the file "session.tcl".
The original code reads:
# Only set beam position if image is from reliable detector
set header_beam_x [$a_dom selectNodes normalize-space(//beam_x)]
set header_beam_y [$a_dom selectNodes normalize-space(//beam_y)]
if {[lsearch [list QUAD Q210 Q315 Q420 SAPPHIRE JUPITER SATURN
MERCURY MARCCD MARMOSAIC MOSAIC4] $detector_model] > -1 ||
$detector_manufacturer == "CBF" } {
updateSetting beam_x $header_beam_x 1 1 "Images"
updateSetting beam_y $header_beam_y 1 1 "Images"
updateSetting backstop_x $header_beam_x 1 1 "Images"
updateSetting backstop_y $header_beam_y 1 1 "Images"
} else {
The required change is to replace "MARMOSAIC" with "MOSAIC3".
This is the ONLY change required.
As this is part of the Tcl for the GUI, NO recompilation is required.
If you do not have access to the source code, a (messy) workaround is
to read an image into ipmosflm (which will read the direct beam
coordinates correctly), make a note of the values, then enter these
values into imosflm (at the head of the "Images" page).
Andrew Leslie and Harry Powell
