diff --git a/wagtail/tests/models.py b/wagtail/tests/models.py
index c419de7c7..086c2af15 100644
--- a/wagtail/tests/models.py
+++ b/wagtail/tests/models.py
@@ -20,6 +20,7 @@ from wagtail.wagtailsnippets.models import register_snippet
 from wagtail.wagtailsnippets.edit_handlers import SnippetChooserPanel
 from wagtail.wagtailsearch import index
 from wagtail.contrib.wagtailroutablepage.models import RoutablePage
+from wagtail.wagtailimages.models import AbstractImage, Image
 
 
 EVENT_AUDIENCE_CHOICES = (
@@ -522,3 +523,17 @@ register_snippet(RegisterFunction)
 @register_snippet
 class RegisterDecorator(models.Model):
     pass
+
+
+class CustomImageWithoutAdminFormFields(AbstractImage):
+    caption = models.CharField(max_length=255)
+    not_editable_field = models.CharField(max_length=255)
+
+
+class CustomImageWithAdminFormFields(AbstractImage):
+    caption = models.CharField(max_length=255)
+    not_editable_field = models.CharField(max_length=255)
+
+    admin_form_fields = Image.admin_form_fields + (
+        'caption',
+    )
diff --git a/wagtail/wagtailimages/forms.py b/wagtail/wagtailimages/forms.py
index faf1dd703..e3db916c8 100644
--- a/wagtail/wagtailimages/forms.py
+++ b/wagtail/wagtailimages/forms.py
@@ -1,7 +1,10 @@
+import warnings
+
 from django import forms
 from django.forms.models import modelform_factory
 from django.utils.translation import ugettext as _
 
+from wagtail.utils.deprecation import RemovedInWagtail11Warning
 from wagtail.wagtailimages.formats import get_image_formats
 from wagtail.wagtailimages.fields import WagtailImageField
 
@@ -17,9 +20,20 @@ def formfield_for_dbfield(db_field, **kwargs):
 
 
 def get_image_form(model):
+    if hasattr(model, 'admin_form_fields'):
+        fields = model.admin_form_fields
+    else:
+        fields = '__all__'
+
+        warnings.warn(
+            "Custom image models without an 'admin_form_fields' attribute are now deprecated. "
+            "Add admin_form_fields = (tuple of field names) to {classname}".format(
+                classname=model.__name__
+            ), RemovedInWagtail11Warning, stacklevel=2)
+
     return modelform_factory(
         model,
-        fields=model.admin_form_fields,
+        fields=fields,
         formfield_callback=formfield_for_dbfield,
         # set the 'file' widget to a FileInput rather than the default ClearableFileInput
         # so that when editing, we don't get the 'currently: ...' banner which is
diff --git a/wagtail/wagtailimages/models.py b/wagtail/wagtailimages/models.py
index 9fd84f2e4..18f1e3aef 100644
--- a/wagtail/wagtailimages/models.py
+++ b/wagtail/wagtailimages/models.py
@@ -67,16 +67,6 @@ class AbstractImage(models.Model, TagSearchable):
     focal_point_width = models.PositiveIntegerField(null=True, blank=True)
     focal_point_height = models.PositiveIntegerField(null=True, blank=True)
 
-    admin_form_fields = (
-        'title',
-        'file',
-        'tags',
-        'focal_point_x',
-        'focal_point_y',
-        'focal_point_width',
-        'focal_point_height',
-    )
-
     def get_usage(self):
         return get_object_usage(self)
 
@@ -235,7 +225,15 @@ class AbstractImage(models.Model, TagSearchable):
 
 
 class Image(AbstractImage):
-    pass
+    admin_form_fields = (
+        'title',
+        'file',
+        'tags',
+        'focal_point_x',
+        'focal_point_y',
+        'focal_point_width',
+        'focal_point_height',
+    )
 
 
 # Do smartcropping calculations when user saves an image without a focal point
diff --git a/wagtail/wagtailimages/tests/tests.py b/wagtail/wagtailimages/tests/tests.py
index f5cde5bd0..cda29df3c 100644
--- a/wagtail/wagtailimages/tests/tests.py
+++ b/wagtail/wagtailimages/tests/tests.py
@@ -1,4 +1,5 @@
 import datetime
+import warnings
 from contextlib import contextmanager
 
 from mock import MagicMock
@@ -11,6 +12,9 @@ from django.db import models
 
 from taggit.forms import TagField, TagWidget
 
+from wagtail.utils.deprecation import RemovedInWagtail11Warning
+from wagtail.tests.models import CustomImageWithAdminFormFields, CustomImageWithoutAdminFormFields
+from wagtail.tests.utils import WagtailTestUtils
 from wagtail.wagtailimages.utils import generate_signature, verify_signature
 from wagtail.wagtailimages.rect import Rect
 from wagtail.wagtailimages.formats import Format, get_image_format, register_image_format
@@ -250,7 +254,7 @@ class TestRect(TestCase):
         self.assertEqual(rect.get_key(), '150-200-100x100')
 
 
-class TestGetImageForm(TestCase):
+class TestGetImageForm(TestCase, WagtailTestUtils):
     def test_fields(self):
         form = get_image_form(Image)
 
@@ -264,24 +268,41 @@ class TestGetImageForm(TestCase):
             'focal_point_height',
         ])
 
-    @contextmanager
-    def patch_admin_form_fields(self, image_model, admin_form_fields):
-        old_admin_form_fields = image_model.admin_form_fields
-        image_model.admin_form_fields = admin_form_fields
-        yield
-        image_model.admin_form_fields = old_admin_form_fields
-
     def test_admin_form_fields_attribute(self):
-        # Remove focal point fields
-        admin_form_fields = Image.admin_form_fields[:-4]
-
-        with self.patch_admin_form_fields(Image, admin_form_fields):
-             form = get_image_form(Image)
+        form = get_image_form(CustomImageWithAdminFormFields)
 
         self.assertEqual(list(form.base_fields.keys()), [
             'title',
             'file',
             'tags',
+            'focal_point_x',
+            'focal_point_y',
+            'focal_point_width',
+            'focal_point_height',
+            'caption',
+        ])
+
+    def test_custom_image_model_without_admin_form_fields_raises_warning(self):
+        self.reset_warning_registry()
+        with warnings.catch_warnings(record=True) as w:
+            form = get_image_form(CustomImageWithoutAdminFormFields)
+
+            # Check that a RemovedInWagtail11Warning has been triggered
+            self.assertEqual(len(w), 1)
+            self.assertTrue(issubclass(w[-1].category, RemovedInWagtail11Warning))
+            self.assertTrue("Add admin_form_fields = (tuple of field names) to CustomImageWithoutAdminFormFields" in str(w[-1].message))
+
+        # All fields, including the not editable one should be on the form
+        self.assertEqual(list(form.base_fields.keys()), [
+            'title',
+            'file',
+            'focal_point_x',
+            'focal_point_y',
+            'focal_point_width',
+            'focal_point_height',
+            'caption',
+            'not_editable_field',
+            'tags',
         ])
 
     def test_file_field(self):