diff --git a/imagedb/serializers.py b/imagedb/serializers.py
index 798c97c15ade5d8b7706b86eabc3bf43aac1a2ff..6c49cb4130f128200ebe35f3a8c8caadcf06a705 100644
--- a/imagedb/serializers.py
+++ b/imagedb/serializers.py
@@ -1,6 +1,6 @@
 
-from composite_field.rest_framework_support import CompositeFieldSerializer
 from rest_framework import serializers
+from composite_field.rest_framework_support import CompositeFieldSerializer
 
 
 from imagedb.models import Instrument, NispDetector, Astrometry, NispRawFrame
@@ -17,14 +17,13 @@ class AstrometrySerializer(serializers.ModelSerializer):
   
   class Meta:
     model = Astrometry
-    exclude = ('ctype1_coordinateType',
-               'ctype1_projectionType',
-               'ctype2_coordinateType',
-               'ctype2_projectionType')    
+    exclude = [f.name for g in Astrometry._meta.get_fields() 
+               if hasattr(g, 'subfields') 
+               for f in g.subfields.values()] 
 
     
 class NispDetectorSerializer(serializers.ModelSerializer):
-  astrometry = AstrometrySerializer(read_only = True)
+  astrometry = AstrometrySerializer()
 
   class Meta:
     model = NispDetector
@@ -38,12 +37,9 @@ class NispRawFrameSerializer(serializers.ModelSerializer):
 
   class Meta:
     model = NispRawFrame
-    exclude = ('commandedPointing_rightAscension',
-               'commandedPointing_declination',
-               'commandedPointing_orientation',
-               'imageType_category',
-               'imageType_firstType',
-               'imageType_secondType')
+    exclude = [f.name for g in NispRawFrame._meta.get_fields() 
+               if hasattr(g, 'subfields') 
+               for f in g.subfields.values()]
     depth = 2
     
     
diff --git a/imagedb_objects.ipynb b/imagedb_objects.ipynb
index 2352072096b44c7634c80a4e6954ec542ad234a0..a46b2508c6edd45c817f0c399cab59a6068505f2 100644
--- a/imagedb_objects.ipynb
+++ b/imagedb_objects.ipynb
@@ -285,12 +285,50 @@
     "obj.delete()"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Serializers\n",
+    "\n",
+    "Let's see some differences between the plain Django serializers and the ModelSerializer class provided by the Django REST framework.\n",
+    "The first example uses the Django core serializers"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": null,
    "metadata": {},
    "outputs": [],
-   "source": []
+   "source": [
+    "from django.core import serializers\n",
+    "\n",
+    "data = serializers.serialize('json',NispRawFrame.objects.filter(observationId=53877, \n",
+    "                            filterWheelPosition='Y').order_by('ditherNumber'))\n",
+    "\n",
+    "print(data)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "The following example, instead, uses the Django REST framework ModelSerializer class. In particular, see the file imagedb/serializers.py"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "from imagedb.serializers import NispRawFrameSerializer\n",
+    "import json\n",
+    "\n",
+    "frame = NispRawFrameSerializer(NispRawFrame.objects.get(id=1))\n",
+    "print(json.dumps(frame.data, indent=2))\n",
+    "\n"
+   ]
   }
  ],
  "metadata": {