Field points from within ZEMAX are defined in the Field Data dialog.  To access the Field Data Dialog, select System > Fields from the main menu, or click on the “Fie” button on the button bar.

Field Data dialog

ZEMAX supports 4 different models for defining fields:

     Angle (Deg) the angle in degrees that the chief ray makes with respect to the object space Z axis.  Note that by definition, the chief ray passes through the center of the entrance pupil, so the field angles are measured with respect to the center of the entrance pupil.  Positive field angles imply positive slope for the ray in the direction of propagation, and thus refer to negative object coordinates.  This option is most useful when at infinite conjugates.
    Object Height the X and Y heights directly on the location of the object (OBJ) surface.  The heights are measured in lens units.  This option cannot be used when at infinite conjugates.
    Paraxial Image Height the paraxial image height location on the image surface.  This option is useful for fixed-frame size designs, such as photographic film in camera systems.  This option only works well with systems which are well described by paraxial optics.
    Real Image Height the REAL image height on the image surface.  This option is also useful for fixed frame designs.  However, ray tracing with this option is slightly slower since ZEMAX must use an iterative approach to determine the proper real ray coordinates of the chief ray on the IMA plane.

For the purposes of the singlet design, we will define the fields in terms of angle.  Rather than having a single field representing the HFOV, three fields will be defined within the requirement of 5 degrees: (0, 0), (0, 3.5), and (0, 5).

Currently, 12 fields can be entered into the Field Data dialog.  Each of these fields can be given a weight, which is primarily useful in optimization.  However, for the purposes of this design, all field weights will be left at 1.  Enter the three fields into the first three entries in the Field Data dialog, as is shown below:

Entering Field Values into ZEMAX

Select "OK" to close the Field Data dialog.