Here's something else I thought to mention (but sorry for the delay) concerning
the camera statements in the various demo scenes.

The cameras are all constructed differently--some radically so. It isn't so much
that they *are* different (since they all 'work') but rather, it's difficult to
get a sense of what is the 'correct' way to state a camera block. (And this
affects how the basic <x,y,z> scene axes are interpreted.)  This could really
confuse a beginner, for various reasons. Granted, the POV-Ray documentation
explains the various camera parameters (and the pitfalls of using
a 'right-hand' coordinate system vs. a left-hand one); but the demo scenes are
probably where new users go first, to get that all-important first taste of the
program, by seeing an actual render and playing around with the code.

Some cameras use old methods, like 'direction' for zooming instead of 'angle.'
And the "benchmark" scene, as well as some others, uses a truly non-standard
set-up-- up z and direction y.

Here's a different example, from DIFFRACT.POV (posted verbatim)...

camera {  //  Camera StdCam
  angle 90
  location  <3.50, -15.00, 3.00>
  direction <0.0,     0.0,  1.6542>
  sky       <0.0,     0.0,  1.0>  // Use right handed-system!
  up        <0.0,     0.0,  1.0>  // Where Z is up
  right     <1.3333,  0.0,  0.0>
  look_at   <0.000, 0.000, -2.7500>
}

In the docs about CAMERA (at "Placing the Camera"), there's a nice diagram which
shows that 'direction' and 'up' are at right-angles to each other--as they
normally should be. Here, they are not.  As the docs about "Up and Right
Vectors" say:

"Note: that the up, right, and direction vectors should always remain
perpendicular to each other or the image will be distorted."

Also, 'up' (and 'sky') are in the z-direction, as well as 'direction.' So that's
not a right-handed coordinate system *according to POV-Ray*. In the docs about
"Handedness" it says:

"To use a right-handed coordinate system...Your thumb still points up in the
+y-direction...."

All of this might sound like nit-picking, but here's why I think it matters:
When I first started learning the program, I picked a demo scene at random to
render and work with...knowing nothing at all about POV-Ray or it's coordinate
axes. The scene happened to be FISH13. Lucky for me, it had an 'understandable'
camera statement, more or less--where the scene's <x,y,z> directions/axes meant
<right,up,into the scene>. Easily grasped, if only from a simple mathematical
standpoint. So if I wanted to change/experiment with something--like translating
one of the objects in +y--then the render actually showed it moving in +y. But
with a few of these demo scenes, that's not at all what will happen in the
render. Trying to learn even the basics of POV-Ray with a non-standard camera
could turn off a new user--there are just too many fundamental details to
comprehend, all at once.

Of course, to fix this situation would mean re-coding some of the scenes
themselves, if they are still to render as originally intended  (a lot of work!)
But an easier solution might be a simple statement, something like "This scene
uses a non-standard camera set-up. (See CAMERA in the included documentation for
details.) If you are new to POV-Ray, you might want to try a different demo
scene."

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