Finding out ORGX ORGY: Difference between revisions

Finding out ORGX ORGY (view source)

Revision as of 11:43, 14 November 2007

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Kay

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 There are different possibilities to find out where the direct beam would hit the detector:
-a) visualize a frame with [[VIEW]], and click (left-mouse) into the middle of the beamstop shadow (or the attenuated direct beam itself, if it is recorded). Use the pixel coordinates displayed by VIEW as ORGX ORGY (in principle you should add 1 to both numbers, because for VIEW the pixels go from 0 to NX-1 whereas for XDS they go from 1 to NX).
+# visualize a frame with [[VIEW]], and click (left-mouse) into the middle of the beamstop shadow (or the attenuated direct beam itself, if it is recorded). Use the pixel coordinates displayed by VIEW as ORGX ORGY (in principle you should add 1 to both numbers, because for VIEW the pixels go from 0 to NX-1 whereas for XDS they go from 1 to NX).<br />Instead of a frame, one could also use FRAME.pck (the FRAME.pck written by COLSPOT is very good for this purpose).
-Instead of a frame, one could also use FRAME.pck (the FRAME.pck written by COLSPOT is very good for this purpose).
+# use adxv for visualization. Otherwise the same as with VIEW. (works for the PILATUS at SLS)
+# use MOSFLM for visualization. It prints out X BEAM and Y BEAM from the frame header, and you may click on the hypothetical direct beam position. However, ''x and y are swapped in MOSFLM when compared to XDS'', and the coordinates are in mm, not in pixels. Sometimes the X BEAM and Y BEAM from the header are not reliable.
-b) use adxv for visualization. Otherwise the same as with VIEW. (works for the PILATUS at SLS)
+# use ice rings to find out where the direct beam would be. This should be rather accurate but may be tedious.
-c) use MOSFLM for visualization. It prints out X BEAM and Y BEAM from the frame header, and you may click on the hypothetical direct beam position. However, ''x and y are swapped in MOSFLM when compared to XDS'', and the coordinates are in mm, not in pixels. Sometimes the X BEAM and Y BEAM from the header are not reliable.
-d) use ice rings to find out where the direct beam would be. This should be rather accurate but may be tedious.
 The error you make in the determination of ORGX ORGY should be less than half of the distance between two spots. If you have a reasonable estimate, but the error is bigger than that, ''you can still find out the true ORGY ORGY by inspecting [[IDXREF.LP]] . This works best if [[COLSPOT]] has seen a significant fraction of all frames.''
 --[[User:Kay|Kay]] 15:03, 9 November 2007 (CET)