diff --git a/graphene_django/fields.py b/graphene_django/fields.py
index 4a85f57..e1972c7 100644
--- a/graphene_django/fields.py
+++ b/graphene_django/fields.py
@@ -156,8 +156,8 @@ class DjangoConnectionField(ConnectionField):
         # AssertionError
         after = min(get_offset_with_default(args.get("after"), -1) + 1, list_length)
 
-        if max_limit is not None and args.get("first", None) == None:
-            if args.get("last", None) != None:
+        if max_limit is not None and args.get("first", None) is None:
+            if args.get("last", None) is not None:
                 after = list_length - args["last"]
             else:
                 args["first"] = max_limit
diff --git a/graphene_django/filter/filterset.py b/graphene_django/filter/filterset.py
index 64453ea..b3333bf 100644
--- a/graphene_django/filter/filterset.py
+++ b/graphene_django/filter/filterset.py
@@ -1,7 +1,6 @@
 import itertools
 
 from django.db import models
-from django_filters import Filter, MultipleChoiceFilter
 from django_filters.filterset import BaseFilterSet, FilterSet
 from django_filters.filterset import FILTER_FOR_DBFIELD_DEFAULTS
 
diff --git a/graphene_django/filter/utils.py b/graphene_django/filter/utils.py
index 9922cc8..ef18a86 100644
--- a/graphene_django/filter/utils.py
+++ b/graphene_django/filter/utils.py
@@ -1,12 +1,9 @@
 import graphene
-
 from django import forms
+from django_filters.utils import get_model_field
 
-from django_filters.utils import get_model_field, get_field_parts
-from django_filters.filters import Filter, BaseCSVFilter
-
-from .filterset import custom_filterset_factory, setup_filterset
 from .filters import ArrayFilter, ListFilter, RangeFilter
+from .filterset import custom_filterset_factory, setup_filterset
 from ..forms import GlobalIDFormField, GlobalIDMultipleChoiceField
 
 
diff --git a/graphene_django/forms/mutation.py b/graphene_django/forms/mutation.py
index cc7d647..e56c99c 100644
--- a/graphene_django/forms/mutation.py
+++ b/graphene_django/forms/mutation.py
@@ -14,10 +14,6 @@ from graphene.types.utils import yank_fields_from_attrs
 from graphene_django.constants import MUTATION_ERRORS_FLAG
 from graphene_django.registry import get_global_registry
 
-
-from django.core.exceptions import ValidationError
-from django.db import connection
-
 from ..types import ErrorType
 from .converter import convert_form_field
 
diff --git a/graphene_django/forms/types.py b/graphene_django/forms/types.py
index 5005040..74e275e 100644
--- a/graphene_django/forms/types.py
+++ b/graphene_django/forms/types.py
@@ -1,3 +1 @@
-import graphene
-
 from ..types import ErrorType  # noqa Import ErrorType for backwards compatability
diff --git a/graphene_django/types.py b/graphene_django/types.py
index 53c4d23..d272412 100644
--- a/graphene_django/types.py
+++ b/graphene_django/types.py
@@ -2,11 +2,8 @@ import warnings
 from collections import OrderedDict
 from typing import Type
 
-from django.db.models import Model
-from django.utils.functional import SimpleLazyObject
-
 import graphene
-from graphene import Field
+from django.db.models import Model
 from graphene.relay import Connection, Node
 from graphene.types.objecttype import ObjectType, ObjectTypeOptions
 from graphene.types.utils import yank_fields_from_attrs
@@ -21,7 +18,6 @@ from .utils import (
     is_valid_django_model,
 )
 
-
 ALL_FIELDS = "__all__"
 
 
@@ -108,12 +104,7 @@ def validate_fields(type_, model, fields, only_fields, exclude_fields):
                 (
                     'Excluding the custom field "{field_name}" on DjangoObjectType "{type_}" has no effect. '
                     'Either remove the custom field or remove the field from the "exclude" list.'
-                ).format(
-                    field_name=name,
-                    app_label=model._meta.app_label,
-                    object_name=model._meta.object_name,
-                    type_=type_,
-                )
+                ).format(field_name=name, type_=type_)
             )
         else:
             if not hasattr(model, name):
@@ -232,7 +223,7 @@ class DjangoObjectType(ObjectType):
 
         django_fields = yank_fields_from_attrs(
             construct_fields(model, registry, fields, exclude, convert_choices_to_enum),
-            _as=Field,
+            _as=graphene.Field,
         )
 
         if use_connection is None and interfaces: