ion with Predefined Operands</h2>

<p>There are several examples of optimization files in the reference
manual. Here is another simple one. We are going to vary the last
surface curvature and its conic constant of the current lens so as to
change the system focal length to 100 mm while at the same time
driving the 3rd order spherical aberration to 0.0. We will keep the
system paraxially focused with a PY solve on the second to last
surface. First, put on the PY solve by typing:</p>

<p><strong>
    U L<br>
