Each rover has a stereo pair of PanCams.  These are the narrow-angle high-resolution science cameras for remote sensing.  To make their panoramas, many individual pictures are joined together to form a mosaic.

To get a good view, the PanCams are mounted at about human eye level on top of a mast.  Full 360 degree azimuth and ±90 degree elevation pointing is provided by a two-axis turret on the mast.  Inside the mast are mirrors to send light down to the infrared Mini-Thermal-Emission Spectrometer, which is protected in the warmer interior of the rover.

The distance between the two PanCams is 280 mm.  This separation will yield hyper-stereo images for better depth perception (the stereo separation or interpupillary distance between human eyes ranges between about 54 mm and 72 mm).

The two PanCams are also the color cameras; each has a filter wheel in front.  Each filter wheel has 8 positions for filters of various wavebands covering the sensitivity range of the CCD.  These allow multi-spectral imaging for quantitative geological and atmospheric studies.  The filter selection is different on the two cameras, although there is some duplication to make the color stereo images.  A sapphire window seals against dust and protects the filter wheel mechanism.

 The PanCam lenses are Cooke Triplets as shown in the layout in Figure 31.1(a).  Focal length is 42.97 mm giving a field of view of 16 x 16 degrees, or 22.5 degrees on the diagonal (the equivalent of a 109 mm lens on a 35 mm camera).  They operate at a constant opening of f/20, view objects in focus whose distances range from infinity to 1500 mm (the depth of field), and are fixed-focused at 3000 mm (the hyperfocal distance).  The two plane-parallel plates in front of the lens in the layout represent the filter and sapphire window.

Figure 31.1(b) is the polychromatic spot diagram.  The scale bar length is 24 µm, which is the dimension of one side of a 2 x 2 matrix of pixels that defines one limiting-resolution detector element.  The circles indicate the diameter of the Airy diffraction disk for a wavelength of 0.43 µm.  The main on-axis aberration is secondary longitudinal color.  Off-axis, there is added astigmatism and secondary lateral color.  But even at the shortest wavelength, these lenses are diffraction limited.  Distortion is less than 0.01% all across the field.  Image illumination at the edge of the field is 93% of the central value (due to cosine-fourth fall-off).

(Actual pictures taken on Mars with the PanCam can be viewed on the last page of the article - Page 10)