diff --git a/examples/knock_knock.hs b/examples/knock_knock.hs
index 02ec1cd..a01e1b2 100755
--- a/examples/knock_knock.hs
+++ b/examples/knock_knock.hs
@@ -49,9 +49,6 @@ main = reanimate $ docEnv $ mapA (withFillOpacity 1) $ sceneAnimation $ do
 
   wait 1
 
-screenTop :: Double
-screenTop = screenHeight/2
-
 oModifyMany :: [Object s a] -> (ObjectData a -> ObjectData a) -> Scene s ()
 oModifyMany os m = forM_ os $ \o -> oModify o m
 
diff --git a/examples/scene_camera.hs b/examples/scene_camera.hs
new file mode 100755
index 0000000..139a118
--- /dev/null
+++ b/examples/scene_camera.hs
@@ -0,0 +1,144 @@
+#!/usr/bin/env stack
+-- stack runghc --package reanimate
+{-# LANGUAGE OverloadedStrings #-}
+module Main(main) where
+
+import Reanimate
+import Reanimate.Builtin.Documentation
+import Reanimate.Scene
+import Control.Lens
+
+main :: IO ()
+{-
+main = reanimate $ docEnv $ mapA (withFillOpacity 1) $ sceneAnimation $ do
+  cam <- newObject Camera
+
+  newSpriteSVG_ $ withStrokeWidth (defaultStrokeWidth*0.5) $ mkGroup
+    [ mkLine (0, screenBottom) (0, screenTop)
+    , mkLine (screenLeft, 0) (screenRight, 0)
+    ]
+
+  box <- newObject $ Rectangle 1 1
+  cameraAttach cam box
+  oModify box $ oContext .~ withFillColor "green"
+  oModify box $ oMargin .~ (0,0,0,0)
+  oModify box $ oLeftX .~ 0
+  oModify box $ oBottomY .~ 0
+  oModify box $ oContext .~ withStrokeWidth 0
+
+  box2 <- newObject $ Rectangle 1 1
+  cameraAttach cam box2
+  oModify box2 $ oContext .~ withFillColor "blue"
+  oModify box2 $ oMargin .~ (0,0,0,0)
+  oModify box2 $ oCenterXY .~ (-2,2)
+  oModify box2 $ oContext .~ withStrokeWidth 0
+
+  dot <- newObject $ Circle 0.05
+  cameraAttach cam dot
+  oModify dot $ oContext .~ withFillColor "red"
+  oModify dot $ oMargin .~ (0,0,0,0)
+  oModify dot $ oCenterXY .~ (0.5,0.5)
+  oModify dot $ oContext .~ withStrokeWidth 0
+
+  dot2 <- newObject $ Circle 0.05
+  cameraAttach cam dot2
+  oModify dot2 $ oContext .~ withFillColor "red"
+  oModify dot2 $ oMargin .~ (0,0,0,0)
+  oModify dot2 $ oCenterXY .~ (-2,2)
+  oModify dot2 $ oContext .~ withStrokeWidth 0
+  
+  oShow box
+  oShow box2
+  oShow dot
+  oShow dot2
+
+  wait 1
+
+  cameraSetFocus cam (0.5, 0.5)
+  waitOn $ do
+    fork $ cameraPan cam 1 (0.5, 0.5)
+    fork $ cameraZoom cam 1 2
+  wait 1
+  cameraSetFocus cam (-2,2)
+  cameraZoom cam 0.5 1.5
+  cameraZoom cam 0.5 2
+  wait 1
+  -- cameraSetFocus cam (-0.5,0.5)
+  waitOn $ do
+    fork $ cameraPan cam 1 (-2, 2)
+    fork $ cameraZoom cam 1 0.5
+  -- oTweenS cam 2 $ \t -> do
+  --   oScale %= \v -> fromToS v 3 t
+  
+  -- cameraSetFocus cam (0.5,0.5)
+  
+  -- oTweenS cam 1 $ \t -> do
+  --   oScale %= \v -> fromToS v 1 t
+  -- wait 4
+  -- oTweenS cam 2 $ \t -> do
+  --   oScaleOrigin .= (fromToS 0.5 (-2) t, fromToS 0.5 2 t)
+  --   oScale .= fromToS 2 1 t
+  --   oTranslate . _1 %= \v -> fromToS v (-2) t
+  --   oTranslate . _2 %= \v -> fromToS v 2 t
+  {-
+    Origin: (-2,2)
+    Translate: (3, -1)
+    New origin: (0.5, 0.5)
+
+    (0.5, 0.5)
+    (0.5+2, 0.5-2)
+    (2.5, -1.5)      origin move
+    (2.5*3, -1.5*3)
+    (7.5, -4.5)      scale
+    (7.5-2, -4.5+2)
+    (5.5, -2.5)      origin move back
+    (5.5-3, -2.5+1)
+    (2.5, -1.5)      translate
+
+    (0.5-2.5, 0.5-(-1.5))
+    (-2, 2)
+  -}
+
+  wait 1
+-}
+main = reanimate $ docEnv $ mapA (withFillOpacity 1) $ sceneAnimation $ do
+  cam <- newObject Camera
+
+  txt <- newObject $ center $ latex "Fixed (non-cam)"
+  oModify txt $
+    oTopY .~ screenTop
+
+  circle <- newObject $ Circle 1
+  cameraAttach cam circle
+  oModify circle $ oContext .~ withFillColor "blue"
+  circleRight <- oRead circle oRightX
+
+  box <- newObject $ Rectangle 2 2
+  cameraAttach cam box
+  oModify box $ oContext .~ withFillColor "green"
+  oModify box $ oLeftX .~ circleRight
+  boxCenter <- oRead box oCenterXY
+
+  small <- newObject $ center $ latex "This text is very small"
+  cameraAttach cam small
+  oModifyS small $ do
+    oCenterXY .= boxCenter
+    oScale .= 0.1
+  
+  oShow txt
+  oShow small
+  oShow circle
+  oShow box
+
+  wait 1
+
+  cameraFocus cam boxCenter
+  waitOn $ do
+    fork $ cameraPan cam 3 boxCenter
+    fork $ cameraZoom cam 3 15
+  
+  wait 2
+  waitOn $ do
+    fork $ cameraZoom cam 3 1
+  waitOn $ do
+    fork $ cameraPan cam 1 (0,0)
diff --git a/src/Reanimate.hs b/src/Reanimate.hs
index bb5498f..c2c02e1 100644
--- a/src/Reanimate.hs
+++ b/src/Reanimate.hs
@@ -179,6 +179,10 @@ module Reanimate
     -- * Constants
     screenWidth,
     screenHeight,
+    screenTop,
+    screenBottom,
+    screenLeft,
+    screenRight,
     defaultDPI,
     defaultStrokeWidth,
     -- * Parameters
diff --git a/src/Reanimate/Constants.hs b/src/Reanimate/Constants.hs
index 5289b66..fe1e46f 100644
--- a/src/Reanimate/Constants.hs
+++ b/src/Reanimate/Constants.hs
@@ -1,16 +1,25 @@
 module Reanimate.Constants
   ( screenWidth
   , screenHeight
+  , screenTop
+  , screenBottom
+  , screenLeft
+  , screenRight
   , defaultDPI
   , defaultStrokeWidth
   ) where
 
 import           Graphics.SvgTree
 
-screenWidth, screenHeight :: Num a => a
+screenWidth, screenHeight, screenTop :: Fractional a => a
+screenBottom, screenLeft, screenRight :: Fractional a => a
 
 screenWidth = 16
 screenHeight = 9
+screenTop = screenHeight/2
+screenBottom = -screenHeight/2
+screenLeft = -screenWidth/2
+screenRight = screenWidth/2
 
 defaultDPI :: Dpi
 defaultDPI = 96