Update manual

1 files changed, 9 insertions, 1 deletions

diff --git a/doc/man/crystfel_geometry.5 b/doc/man/crystfel_geometry.5
index d38f30fd..7588bde6 100644
--- a/doc/man/crystfel_geometry.5
+++ b/doc/man/crystfel_geometry.5
@@ -166,7 +166,7 @@ The camera length offset (in metres) for this panel.  This number will be added
 .IP \fBfs\fR
 .IP \fBss\fR
 .PD
-For this panel, the fast and slow scan directions correspond to the given directions in the lab coordinate system described above, measured in pixels.  Example: "panel0/fs = 0.5x+0.5y".  Note that (in the current version) the directions must be perpendicular to the beam direction, i.e. contain components in the x and y directions only.
+For this panel, the fast and slow scan directions correspond to the given directions in the lab coordinate system described above, measured in pixels.  Example: "panel0/fs = 0.5x+0.5y-0.0001z".  Including a component in the z direction means that the panel normal is not parallel to the X-ray beam.
 
 .PD 0
 .IP \fBcorner_x\fR
@@ -210,6 +210,14 @@ mask_bad = 0x00
 .IP \fBno_index\fR
 Set this to 1 or "true" to ignore this panel completely.
 
+.PD 0
+.IP \fBrail_x\fR
+.IP \fBrail_y\fR
+.IP \fBrail_z\fR
+.IP \fBclen_for_centering\fR
+.PD
+Specify the direction in which the panel should move when the camera length is increased.  \fBclen_for_centering\fR is the camera length at which the central beam intersects the centre of the detector.  If you've only calibrated the detector at one camera length, perhaps using prior known values for the rail direction, then this should be the camera length at which you calibrated the detector.  \fBclen_for_centering\fR is the camera length \fBbefore\fR applying the \fBcoffset\fR, i.e. for CSPAD/CXI/LCLS data this value should be an "encoder value" in metres. If you specify any of the rail_{x,y,z} values, you must also specify clen_for_centering.  The default is for the panel to move in the +z direction, so rail_x=0, rail_y=0, rail_z=1 and clen_for_centering is irrelevant.  The square root of the sum of the squares of the rail values (i.e. the modulus of the "rail vector") should normally be equal to one.  Otherwise, the camera length changes from the centering value will be correspondingly scaled.
+
 .SH BAD REGIONS
 
 You can also specify bad regions.  Bad regions will be completely ignored by CrystFEL.  Bad regions are specified in pixel units, either in the lab coordinate system (see above) or in fast scan/slow scan coordinates (mixtures are not allowed).   In the latter case, the range of pixels is specified \fIinclusively\fR.  Bad regions are distinguished from normal panels by the fact that they begin with the three letters "bad".