diff --git a/esbo-etc_defaults.xml b/esbo-etc_defaults.xml
index 6f7c55b..760f209 100644
--- a/esbo-etc_defaults.xml
+++ b/esbo-etc_defaults.xml
@@ -1,12 +1,12 @@
 <root>
     <common>
-        <wl_min val="400" units="nanometer" comment="Shortest wavelength used for binning input spectra"/>
-        <wl_max val="5" units="micron" comment="Shortest wavelength used for binning input spectra"/>
-        <wl_delta val="10" units="nanometer" comment="Wavelength increment used for binning input spectra"/>
-<!--        <res val="1000" units=""-->
+        <wl_min val="400" val_unit="nm" comment="Shortest wavelength used for binning input spectra"/>
+        <wl_max val="500" val_unit="nm" comment="Shortest wavelength used for binning input spectra"/>
+        <wl_delta val="10" val_unit="nm" comment="Wavelength increment used for binning input spectra"/>
+<!--        <res val="1000" val_unit=""-->
 <!--                   comment="Resolving power for common spectral binning. A linear binning wavelength integral is estimated as wl_min/R"/>-->
-        <d_aperture val="5" units="m" comment="Diameter of the telescope aperture"/>
-        <jitter_rms val="0.1" units="arcsec" comment="Sigma RMS of the telescope jitter"/>
+        <d_aperture val="5" val_unit="m" comment="Diameter of the telescope aperture"/>
+        <jitter_rms val="0.1" val_unit="arcsec" comment="Sigma RMS of the telescope jitter"/>
         <output_path val="output" comment="Output directory to store output files"/>
     </common>
 
@@ -17,38 +17,38 @@
     </noise>
 
     <astroscene>
-        <target type="BlackBodyTarget" val="5778" units="K" mag="10" band="G"
+        <target type="BlackBodyTarget" temp="5778" temp_unit="K" mag="10" band="V"
                 comment="Modeling the sun as mag 10 star"/>
-        <optical_component type="Atmosphere" transmissivity="data/atmosphere/transmittance.csv"
+        <optical_component type="Atmosphere" transmittance="data/atmosphere/transmittance.csv"
                            emission="data/atmosphere/emission.csv" comment="Including the atmosphere"/>
         <optical_component type="StrayLight" emission="data/strayLight/emission.csv"
                            comment="Including arbitrary noise sources"/>
     </astroscene>
 
     <common_optics>
-        <optical_component type="Mirror" reflectivity="data/mirror/reflectivity.csv"
-                           emissivity="data/mirror/emissivity.csv" val="70" units="K" comment="M1"/>
-        <optical_component type="Mirror" reflectivity="data/mirror/reflectivity.csv"
-                           emissivity="data/mirror/emissivity.csv" val="70" units="K" comment="M2"/>
-        <optical_component type="Mirror" reflectivity="data/mirror/reflectivity.csv"
-                           emissivity="data/mirror/emissivity.csv" val="70" units="K" comment="M3"/>
-        <optical_component type="Filter" band="G"
-                           emissivity="data/filter/emissivity.csv" val="70" units="K" comment="Filter wheel"/>
+        <optical_component type="Mirror" reflectance="data/mirror/reflectance.csv"
+                           emissivity="data/mirror/emissivity.csv" temp="70" temp_unit="K" comment="M1"/>
+        <optical_component type="Mirror" reflectance="data/mirror/reflectance.csv"
+                           emissivity="data/mirror/emissivity.csv" temp="70" temp_unit="K" comment="M2"/>
+        <optical_component type="Mirror" reflectance="data/mirror/reflectance.csv"
+                           emissivity="data/mirror/emissivity.csv" temp="70" temp_unit="K" comment="M3"/>
+<!--        <optical_component type="Filter" band="B"-->
+<!--                           emissivity="data/filter/emissivity.csv" val="70" val_unit="K" comment="Filter wheel"/>-->
+        <optical_component type="Filter" start="400" start_unit="nm" end="480" end_unit="nm"
+                           emissivity="data/filter/emissivity.csv" temp="70" temp_unit="K" comment="Filter wheel"/>
     </common_optics>
 
     <instrument>
-        <optical_component type="Mirror" reflectivity="data/mirror/reflectivity.csv"
-                           emissivity="data/mirror/emissivity.csv" val="70" units="K" comment="M4"/>
-        <optical_component type="Filter" band="G"
-                           emissivity="data/filter/emissivity.csv" val="70" units="K" comment="Filter wheel"/>
+        <optical_component type="Lens" transmittance="data/lens/transmittance.csv"
+                           emissivity="data/lens/emissivity.csv" temp="70" temp_unit="K" comment="M4"/>
         <sensor type="CCD">
-            <f_number val="18.5" units="" comment="The working f/#"/>
-            <pixel_geometry val="1024, 1024" units="" comment="Pixel geometry"/>
+            <f_number val="18.5" val_unit="" comment="The working f/#"/>
+            <pixel_geometry val="1024, 1024" val_unit="" comment="Pixel geometry"/>
             <pixel>
                 <quantum_efficiency val="data/ccd/qe.csv" comment="Quantum efficiency of the detector pixel"/>
-                <pixel_size val="15" units="micron"/>
-                <dark_current val="20" units="1/s" comment="Detector dark current"/>
-                <sigma_read_out val="10.0" units="" comment="Detector readout noise in e-rms"/>
+                <pixel_size val="15" val_unit="micron"/>
+                <dark_current val="20" val_unit="1/s" comment="Detector dark current"/>
+                <sigma_read_out val="10.0" val_unit="" comment="Detector readout noise in e-rms"/>
             </pixel>
         </sensor>
     </instrument>
diff --git a/esbo_etc/classes/config.py b/esbo_etc/classes/config.py
index fd2da6b..089eadb 100644
--- a/esbo_etc/classes/config.py
+++ b/esbo_etc/classes/config.py
@@ -5,6 +5,7 @@ import os
 import logging
 from ..lib.helpers import error
 from typing import Union
+import re
 
 
 class Entry(object):
@@ -33,17 +34,22 @@ class Entry(object):
         # Copy the XML attributes to object attributes
         for attrib in xml.attrib.keys():
             setattr(self, attrib, xml.attrib[attrib])
-
-        # Convert to python datatype and apply the corresponding unit (if applicable)
-        if hasattr(self, 'units'):
-            try:
-                self.val = u.Quantity(list(map(float, self.val.split(','))),
-                                      self.units)
-                if len(self.val) == 1:
-                    self.val = self.val[0]
-            except (ValueError, LookupError):
-                error("unable to convert units in entry '" + xml.tag + "': " + self.val + " " + self.units, exit_=False)
-        elif hasattr(self, "val") and self.val.lower() in ["false", "true"]:
+        # parse units
+        attribs = list(xml.attrib.keys())
+        units = list(filter(re.compile(".*_unit$").match, attribs))
+        for unit in units:
+            var = unit.replace("_unit", "")
+            if hasattr(self, var):
+                try:
+                    val = u.Quantity(list(map(float, getattr(self, var).split(','))), getattr(self, unit))
+                    if len(val) == 1:
+                        val = val[0]
+                    setattr(self, var, val)
+                except (ValueError, LookupError):
+                    error("unable to convert units in entry '" + xml.tag + "': " + getattr(self, var) + " "  +
+                          getattr(self, unit),  exit_=False)
+        # Convert boolean values
+        if hasattr(self, "val") and type(self.val) == str and self.val.lower() in ["false", "true"]:
             self.val = (self.val.lower() == "true")
 
 
diff --git a/tests/data/esbo-etc_defaults.xml b/tests/data/esbo-etc_defaults.xml
index 6f7c55b..760f209 100644
--- a/tests/data/esbo-etc_defaults.xml
+++ b/tests/data/esbo-etc_defaults.xml
@@ -1,12 +1,12 @@
 <root>
     <common>
-        <wl_min val="400" units="nanometer" comment="Shortest wavelength used for binning input spectra"/>
-        <wl_max val="5" units="micron" comment="Shortest wavelength used for binning input spectra"/>
-        <wl_delta val="10" units="nanometer" comment="Wavelength increment used for binning input spectra"/>
-<!--        <res val="1000" units=""-->
+        <wl_min val="400" val_unit="nm" comment="Shortest wavelength used for binning input spectra"/>
+        <wl_max val="500" val_unit="nm" comment="Shortest wavelength used for binning input spectra"/>
+        <wl_delta val="10" val_unit="nm" comment="Wavelength increment used for binning input spectra"/>
+<!--        <res val="1000" val_unit=""-->
 <!--                   comment="Resolving power for common spectral binning. A linear binning wavelength integral is estimated as wl_min/R"/>-->
-        <d_aperture val="5" units="m" comment="Diameter of the telescope aperture"/>
-        <jitter_rms val="0.1" units="arcsec" comment="Sigma RMS of the telescope jitter"/>
+        <d_aperture val="5" val_unit="m" comment="Diameter of the telescope aperture"/>
+        <jitter_rms val="0.1" val_unit="arcsec" comment="Sigma RMS of the telescope jitter"/>
         <output_path val="output" comment="Output directory to store output files"/>
     </common>
 
@@ -17,38 +17,38 @@
     </noise>
 
     <astroscene>
-        <target type="BlackBodyTarget" val="5778" units="K" mag="10" band="G"
+        <target type="BlackBodyTarget" temp="5778" temp_unit="K" mag="10" band="V"
                 comment="Modeling the sun as mag 10 star"/>
-        <optical_component type="Atmosphere" transmissivity="data/atmosphere/transmittance.csv"
+        <optical_component type="Atmosphere" transmittance="data/atmosphere/transmittance.csv"
                            emission="data/atmosphere/emission.csv" comment="Including the atmosphere"/>
         <optical_component type="StrayLight" emission="data/strayLight/emission.csv"
                            comment="Including arbitrary noise sources"/>
     </astroscene>
 
     <common_optics>
-        <optical_component type="Mirror" reflectivity="data/mirror/reflectivity.csv"
-                           emissivity="data/mirror/emissivity.csv" val="70" units="K" comment="M1"/>
-        <optical_component type="Mirror" reflectivity="data/mirror/reflectivity.csv"
-                           emissivity="data/mirror/emissivity.csv" val="70" units="K" comment="M2"/>
-        <optical_component type="Mirror" reflectivity="data/mirror/reflectivity.csv"
-                           emissivity="data/mirror/emissivity.csv" val="70" units="K" comment="M3"/>
-        <optical_component type="Filter" band="G"
-                           emissivity="data/filter/emissivity.csv" val="70" units="K" comment="Filter wheel"/>
+        <optical_component type="Mirror" reflectance="data/mirror/reflectance.csv"
+                           emissivity="data/mirror/emissivity.csv" temp="70" temp_unit="K" comment="M1"/>
+        <optical_component type="Mirror" reflectance="data/mirror/reflectance.csv"
+                           emissivity="data/mirror/emissivity.csv" temp="70" temp_unit="K" comment="M2"/>
+        <optical_component type="Mirror" reflectance="data/mirror/reflectance.csv"
+                           emissivity="data/mirror/emissivity.csv" temp="70" temp_unit="K" comment="M3"/>
+<!--        <optical_component type="Filter" band="B"-->
+<!--                           emissivity="data/filter/emissivity.csv" val="70" val_unit="K" comment="Filter wheel"/>-->
+        <optical_component type="Filter" start="400" start_unit="nm" end="480" end_unit="nm"
+                           emissivity="data/filter/emissivity.csv" temp="70" temp_unit="K" comment="Filter wheel"/>
     </common_optics>
 
     <instrument>
-        <optical_component type="Mirror" reflectivity="data/mirror/reflectivity.csv"
-                           emissivity="data/mirror/emissivity.csv" val="70" units="K" comment="M4"/>
-        <optical_component type="Filter" band="G"
-                           emissivity="data/filter/emissivity.csv" val="70" units="K" comment="Filter wheel"/>
+        <optical_component type="Lens" transmittance="data/lens/transmittance.csv"
+                           emissivity="data/lens/emissivity.csv" temp="70" temp_unit="K" comment="M4"/>
         <sensor type="CCD">
-            <f_number val="18.5" units="" comment="The working f/#"/>
-            <pixel_geometry val="1024, 1024" units="" comment="Pixel geometry"/>
+            <f_number val="18.5" val_unit="" comment="The working f/#"/>
+            <pixel_geometry val="1024, 1024" val_unit="" comment="Pixel geometry"/>
             <pixel>
                 <quantum_efficiency val="data/ccd/qe.csv" comment="Quantum efficiency of the detector pixel"/>
-                <pixel_size val="15" units="micron"/>
-                <dark_current val="20" units="1/s" comment="Detector dark current"/>
-                <sigma_read_out val="10.0" units="" comment="Detector readout noise in e-rms"/>
+                <pixel_size val="15" val_unit="micron"/>
+                <dark_current val="20" val_unit="1/s" comment="Detector dark current"/>
+                <sigma_read_out val="10.0" val_unit="" comment="Detector readout noise in e-rms"/>
             </pixel>
         </sensor>
     </instrument>