diff --git a/Wrappers/Python/cil/io/ZEISSDataReader.py b/Wrappers/Python/cil/io/ZEISSDataReader.py
index 6ec368804..11d89363f 100644
--- a/Wrappers/Python/cil/io/ZEISSDataReader.py
+++ b/Wrappers/Python/cil/io/ZEISSDataReader.py
@@ -133,12 +133,22 @@ def set_up(self,
             for key in roi.keys():
                 idx = zeiss_data_order[key]
                 if roi[key] != -1:
+                    if key == AcquisitionDimension.ANGLE:
+                        if roi[key][1] > default_roi[0][1]:
+                            raise ValueError('Requested angle range {} exceeds maximum of {}'.format(roi[key], default_roi[0][1]))
+                    elif key == ImageDimension.VERTICAL or key == AcquisitionDimension.VERTICAL:
+                        if roi[key][1] > default_roi[1][1]:
+                            raise ValueError('Requested vertical range {} exceeds maximum of {}'.format(roi[key], default_roi[1][1]))
+                    elif key == ImageDimension.HORIZONTAL_X or key == ImageDimension.HORIZONTAL_Y or key == AcquisitionDimension.HORIZONTAL:
+                        if roi[key][1] > default_roi[2][1]:
+                            raise ValueError('Requested horizontal range {} exceeds maximum of {}'.format(roi[key], default_roi[2][1]))
+
                     for i, x in enumerate(roi[key]):
                         if x is None:
                             continue
 
                         if i != 2: #start and stop
-                            default_roi[idx][i] = x if x >= 0 else default_roi[idx][1] - x
+                            default_roi[idx][i] = x if x >= 0 else default_roi[idx][1] + x
                         else: #step
                             default_roi[idx][i] =  x if x > 0 else 1