diff --git a/pytorch3d/renderer/cameras.py b/pytorch3d/renderer/cameras.py
index d3d4ff24..3f411525 100644
--- a/pytorch3d/renderer/cameras.py
+++ b/pytorch3d/renderer/cameras.py
@@ -886,8 +886,8 @@ def compute_projection_matrix(
 
         # NOTE: This maps the z coordinate to the range [0, 1] and replaces the
         # the OpenGL z normalization to [-1, 1]
-        K[:, 2, 2] = z_sign * (1.0 / (zfar - znear)) * scale_xyz[:, 2]
-        K[:, 2, 3] = -znear / (zfar - znear)
+        K[:, 2, 2] = z_sign * (2.0 / (zfar - znear)) * scale_xyz[:, 2]
+        K[:, 2, 3] = -2*znear / (zfar - znear)
 
         return K
 
@@ -910,12 +910,12 @@ def get_projection_transform(self, **kwargs) -> Transform3d:
             scale_z = 2 / (far-near)
             mid_x = (max_x + min_x) / (max_x - min_x)
             mix_y = (max_y + min_y) / (max_y - min_y)
-            mid_z = (far + near) / (far - near)
+            mid_z = 2 * near / (far - near)
 
             K = [
                     [scale_x,        0,         0,  -mid_x],
                     [0,        scale_y,         0,  -mix_y],
-                    [0,              0,  -scale_z,  -mid_z],
+                    [0,              0,  scale_z,  -mid_z],
                     [0,              0,         0,       1],
             ]
         """