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    Re: Camera sextant? was: Re: On The Water Trial of Digital Camera CN
    From: George Huxtable
    Date: 2010 Jul 5, 23:29 +0100

    Marcel asked-|
    "I don't really understand why George thinks that this function can't be
    quadratic."
    
    Here's where I need a blackboard, but this attached sketch will have to do.
    Sorry about its crudity.
    
    If we accept that a ray that's on the optical central axis will produce a
    spot in the centre of the array, at (0,0), and that the response must be
    anti-symmetric about that centre, it should be clear that any quadratic
    component, added in to the basically linear variation with angle, creates a
    curve that cannot meet that requirement for anti-symmetry. On the other
    hand, a cubic term, being in itself antisymmetric about the origin,
    presents no such problem. It's as simple as that.
    
    George.
    
    contact George Huxtable, at  george@hux.me.uk
    or at +44 1865 820222 (from UK, 01865 820222)
    or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
    
    
    
    
    

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