a problem that confused me is that the real cameras don't let me read all the nodes
and for some reason i didn't see the error messages within the inferior-lisp buffer
in emacs. i only realized this after running the code directly from command line:

martin@localhost ~/arduino_due_lisp/pylon $ sbcl --load test-pylon.lisp
This is SBCL 1.2.0.129-c06b8c1, an implementation of ANSI Common Lisp.
More information about SBCL is available at <http://www.sbcl.org/>.

SBCL is free software, provided as is, with absolutely no warranty.
It is mostly in the public domain; some portions are provided under
BSD-style licenses.  See the CREDITS and COPYING files in the
distribution for more information.
creating factory
finding devices
preparing camera array
attaching cameras
camera 0
Using device acA1920-25gm
Exception caught in pylon_wrapper_get_max_i msg=Node is not readable. : AccessException thrown in node 'N381' while calling 'N381.GetValue()' (file 'IntegerT.h', line 148)
Exception caught in pylon_wrapper_get_max_i msg=Node is not readable. : AccessException thrown in node 'N367' while calling 'N367.GetValue()' (file 'IntegerT.h', line 148)
Exception caught in pylon_wrapper_get_value_i msg=Node is not readable. : AccessException thrown in node 'Width' while calling 'Width.GetValue()' (file 'IntegerT.h', line 148)
Exception caught in pylon_wrapper_get_value_i msg=Node is not readable. : AccessException thrown in node 'Height' while calling 'Height.GetValue()' (file 'IntegerT.h', line 148)
Exception caught in pylon_wrapper_get_value_i msg=Node is not readable. : AccessException thrown in node 'OffsetX' while calling 'OffsetX.GetValue()' (file 'IntegerT.h', line 148)
Exception caught in pylon_wrapper_get_value_i msg=Node is not readable. : AccessException thrown in node 'OffsetY' while calling 'OffsetY.GetValue()' (file 'IntegerT.h', line 148)
Exception caught in pylon_wrapper_to_string_e msg=Node is not readable : AccessException thrown in node 'PixelFormat' while calling 'PixelFormat.ToString()' (file 'ValueT.h', line 63)
Exception caught in pylon_wrapper_from_string_e msg=Node is not writable : AccessException thrown in node 'PixelFormat' while calling 'PixelFormat.FromString()' (file 'ValueT.h', line 85)
Exception caught in pylon_wrapper_get_value_e msg=Node is not readable. : AccessException thrown in node 'PixelFormat' while calling 'PixelFormat.GetIntValue()' (file 'EnumerationT.h', line 131)
Exception caught in pylon_wrapper_start_grabbing msg=Could not apply configuration. GenICam::GenericException caught in OnOpened method msg=Node is not writable : AccessException thrown in node 'AcquisitionMode' while calling 'AcquisitionMode.FromString()' (file 'ValueT.h', line 85) : RuntimeException thrown (file 'AcquireContinuousConfiguration.h', line 77)