diff --git a/rtiow/src/bin/tracer.rs b/rtiow/src/bin/tracer.rs
index 16caa7b..607591d 100644
--- a/rtiow/src/bin/tracer.rs
+++ b/rtiow/src/bin/tracer.rs
@@ -3,7 +3,9 @@ extern crate rtiow;
 #[macro_use]
 extern crate structopt;
 
+use std::fmt;
 use std::path::PathBuf;
+use std::str;
 use std::time::Instant;
 
 use rand::Rng;
@@ -91,66 +93,21 @@ fn random_scene() -> Vec<Box<Hit>> {
     objects
 }
 
-fn build_scene(opt: &Opt) -> Scene {
-    let (camera, world) = if BOOK_COVER {
-        let lookfrom = Vec3::new(13., 2., 3.);
-        let lookat = Vec3::new(0., 0., 0.);
-        let dist_to_focus = 10.;
-        let aperture = 0.1;
-        let cam = Camera::new(
-            lookfrom,
-            lookat,
-            Vec3::new(0., 1., 0.),
-            20.,
-            opt.width as f32 / opt.height as f32,
-            aperture,
-            dist_to_focus,
-        );
-        let world = HitableList::new(random_scene());
-        (cam, world)
-    } else {
-        let lookfrom = Vec3::new(3., 3., 2.);
-        let lookat = Vec3::new(0., 0., -1.);
-        let dist_to_focus = (lookfrom - lookat).length();
-        let aperture = 2.;
-        let cam = Camera::new(
-            lookfrom,
-            lookat,
-            Vec3::new(0., 1., 0.),
-            20.,
-            opt.width as f32 / opt.height as f32,
-            aperture,
-            dist_to_focus,
-        );
-        let world = HitableList::new(vec![
-            Box::new(Sphere::new(
-                Vec3::new(0., 0., -1.),
-                0.5,
-                Box::new(Lambertian::new(Vec3::new(0.1, 0.2, 0.5))),
-            )),
-            Box::new(Sphere::new(
-                Vec3::new(0., -100.5, -1.),
-                100.,
-                Box::new(Lambertian::new(Vec3::new(0.8, 0.8, 0.))),
-            )),
-            Box::new(Sphere::new(
-                Vec3::new(1., 0., -1.),
-                0.5,
-                Box::new(Metal::new(Vec3::new(0.8, 0.6, 0.2), 0.2)),
-            )),
-            Box::new(Sphere::new(
-                Vec3::new(-1., 0., -1.),
-                0.5,
-                Box::new(Dielectric::new(1.5)),
-            )),
-            Box::new(Sphere::new(
-                Vec3::new(-1., 0., -1.),
-                -0.45,
-                Box::new(Dielectric::new(1.5)),
-            )),
-        ]);
-        (cam, world)
-    };
+fn build_scene_book(opt: &Opt) -> Scene {
+    let lookfrom = Vec3::new(13., 2., 3.);
+    let lookat = Vec3::new(0., 0., 0.);
+    let dist_to_focus = 10.;
+    let aperture = 0.1;
+    let camera = Camera::new(
+        lookfrom,
+        lookat,
+        Vec3::new(0., 1., 0.),
+        20.,
+        opt.width as f32 / opt.height as f32,
+        aperture,
+        dist_to_focus,
+    );
+    let world = HitableList::new(random_scene());
     Scene {
         camera,
         world,
@@ -160,8 +117,84 @@ fn build_scene(opt: &Opt) -> Scene {
     }
 }
 
+fn build_scene_tutorial(opt: &Opt) -> Scene {
+    let lookfrom = Vec3::new(3., 3., 2.);
+    let lookat = Vec3::new(0., 0., -1.);
+    let dist_to_focus = (lookfrom - lookat).length();
+    let aperture = 0.1;
+    let camera = Camera::new(
+        lookfrom,
+        lookat,
+        Vec3::new(0., 1., 0.),
+        45.,
+        opt.width as f32 / opt.height as f32,
+        aperture,
+        dist_to_focus,
+    );
+    let world = HitableList::new(vec![
+        Box::new(Sphere::new(
+            Vec3::new(0., 0., -1.),
+            0.5,
+            Box::new(Lambertian::new(Vec3::new(0.1, 0.2, 0.5))),
+        )),
+        Box::new(Sphere::new(
+            Vec3::new(0., -100.5, -1.),
+            100.,
+            Box::new(Lambertian::new(Vec3::new(0.8, 0.8, 0.))),
+        )),
+        Box::new(Sphere::new(
+            Vec3::new(1., 0., -1.),
+            0.5,
+            Box::new(Metal::new(Vec3::new(0.8, 0.6, 0.2), 0.2)),
+        )),
+        Box::new(Sphere::new(
+            Vec3::new(-1., 0., -1.),
+            0.5,
+            Box::new(Dielectric::new(1.5)),
+        )),
+        Box::new(Sphere::new(
+            Vec3::new(-1., 0., -1.),
+            -0.45,
+            Box::new(Dielectric::new(1.5)),
+        )),
+    ]);
+    Scene {
+        camera,
+        world,
+        subsamples: opt.subsamples,
+        width: opt.width,
+        height: opt.height,
+    }
+}
+
+#[derive(Debug)]
+pub enum Model {
+    Book,
+    Tutorial,
+}
+
+#[derive(Debug)]
+pub struct ModelParseError(String);
+
+impl fmt::Display for ModelParseError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "unknown model enum type '{}'", self.0)
+    }
+}
+
+impl str::FromStr for Model {
+    type Err = ModelParseError;
+    fn from_str(s: &str) -> std::result::Result<Self, Self::Err> {
+        match s {
+            "book" => Ok(Model::Book),
+            "tutorial" => Ok(Model::Tutorial),
+            _ => Err(ModelParseError(s.to_owned())),
+        }
+    }
+}
+
 #[derive(Debug, StructOpt)]
-#[structopt(name = "tracert", about = "An experimental ray tracer.")]
+#[structopt(name = "tracer", about = "An experimental ray tracer.")]
 pub struct Opt {
     /// Image width
     #[structopt(short = "w", long = "width", default_value = "1280")]
@@ -172,6 +205,8 @@ pub struct Opt {
     /// Sub-samples per pixel
     #[structopt(short = "s", long = "subsample", default_value = "10")]
     pub subsamples: usize,
+    #[structopt(long = "model")]
+    pub model: Model,
 
     /// Output directory
     #[structopt(parse(from_os_str))]
@@ -181,7 +216,10 @@ pub struct Opt {
 fn main() -> Result<(), std::io::Error> {
     let start = Instant::now();
     let opt = Opt::from_args();
-    let scene = build_scene(&opt);
+    let scene = match opt.model {
+        Model::Book => build_scene_book(&opt),
+        Model::Tutorial => build_scene_tutorial(&opt),
+    };
     let res = render(scene, &opt.output);
     let runtime = start.elapsed();
     eprintln!(