diff --git a/bin/defocus.c b/bin/defocus.c
index 4de3679..9bebb00 100644
--- a/bin/defocus.c
+++ b/bin/defocus.c
@@ -4,12 +4,14 @@
 #include <defocus/defocus.h>
 
 int pinhole_fn(int argc, char **argv);
+int thin_lense_fn(int argc, char **argv);
 
-static const char *_model_names[] = {"pinhole"};
+static const char *_model_names[] = {"pinhole", "thin_lense"};
 typedef int (*model_fn)(int argc, char **argv);
 
 static model_fn _model_fns[] = {
     pinhole_fn,
+    thin_lense_fn,
 };
 
 void usage(const char *pname)
@@ -121,3 +123,9 @@ int pinhole_fn(int argc, char **argv)
 
     return error_code;
 }
+
+int thin_lense_fn(int argc, char **argv)
+{
+    fprintf(stderr, "Not implemented yet");
+    return 1;
+}
\ No newline at end of file
diff --git a/include/defocus/defocus.h b/include/defocus/defocus.h
index 4c9dcb9..2efba8d 100644
--- a/include/defocus/defocus.h
+++ b/include/defocus/defocus.h
@@ -6,6 +6,6 @@
  */
 #include "base.h"
 #include "image.h"
-#include "pinhole.h"
+#include "models.h"
 
 #endif
diff --git a/include/defocus/models.h b/include/defocus/models.h
new file mode 100644
index 0000000..26e72af
--- /dev/null
+++ b/include/defocus/models.h
@@ -0,0 +1,40 @@
+#ifndef DF_MODELS_H
+#define DF_MODELS_H
+
+/** @file models.h
+ * @brief Camera models for defocus.
+ *
+ * Camera models are usually implemented as a function taking an input image and parameters required for the model
+ * and produce an output image.
+ *
+ * All camera models use the same coordinate space: The camera looks along the positive z-axis in a right-handed
+ * coordinate system.  (-> positive y is down, positive x is right.)
+ */
+
+#include "image.h"
+
+/** @brief Simple pinhole camera model.
+ *
+ * The simplest possible(?) camera model.
+ * This function takes an input image at a known distance from the camera and moves it to a new distance.
+ *
+ * @param in_image input image
+ * @param focal_length the cameras focal length in millimeters.
+ * @param orig_z the distance of the input image from the camera.
+ * @param new_z the distance of the generated output image.
+ * @param out_image the output image.
+ */
+void df_pinhole(const df_image *in_image, float focal_length, float orig_z, float new_z, df_image *out_image);
+
+/** @brief Thin-lense model.
+ *
+ * @param in_image input image
+ * @param focal_length the cameras focal length in millimeters.
+ * @param aperture the aperture size in millimeters.
+ * @param orig_z the distnce of the input image from the camera.
+ * @param out_image the output image.
+ */
+void df_thin_lense(
+    const df_image *in_image, float focal_length, float aperture, float orig_z, float new_z, df_image *out_image);
+
+#endif
diff --git a/include/defocus/pinhole.h b/include/defocus/pinhole.h
deleted file mode 100644
index 1c378e6..0000000
--- a/include/defocus/pinhole.h
+++ /dev/null
@@ -1,12 +0,0 @@
-#ifndef DF_PINHOLE_H
-#define DF_PINHOLE_H
-
-/** @file pinhole.h
- * @brief Defocus based on pinhole camera model.
- */
-
-#include "image.h"
-
-void df_pinhole(const df_image *in_image, float focal_length, float orig_z, float new_z, df_image *out_image);
-
-#endif
diff --git a/lib/pinhole.c b/lib/pinhole.c
index 02a6f7f..af2538d 100644
--- a/lib/pinhole.c
+++ b/lib/pinhole.c
@@ -1,4 +1,4 @@
-#include <defocus/pinhole.h>
+#include <defocus/models.h>
 #include <defocus/base.h>
 #include <defocus/image.h>
 
diff --git a/lib/thin_lense.c b/lib/thin_lense.c
new file mode 100644
index 0000000..1c048b2
--- /dev/null
+++ b/lib/thin_lense.c
@@ -0,0 +1,6 @@
+#include <defocus/models.h>
+
+void df_thin_lense(
+    const df_image *in_image, float focal_length, float aperture, float orig_z, float new_z, df_image *out_image)
+{
+}
\ No newline at end of file
diff --git a/meson.build b/meson.build
index 8bbdac9..84f5252 100644
--- a/meson.build
+++ b/meson.build
@@ -11,6 +11,7 @@ lib = library('df',
               'lib/pinhole.c',
               'lib/image.c',
               'lib/color.c',
+              'lib/thin_lense.c',
               include_directories: incdir,
               dependencies: m_dep,
               version: '0.1.0',