Fig. 29.

Derived best focus position and MTF at Nyquist as a function of filter for a fixed target position. As in Fig. 25, a focus stack was taken for a fixed target position for each filter and the best-focus image was determined from the maximum measured MTF at Nyquist. Left: Comparison of the derived best focus motor position vs filter. For the visible band filters, we find a roughly constant focus position vs wavelength, resulting from the narrower range of wavelengths, suggesting a single autofocus frame can be acquired for all filters. For the near-IR filters, we find a systematic trend towards fewer motor counts for increasing wavelength. Right: Comparison of the derived best MTF value at Nyquist vs filter. For both cameras, we find a comparable decrease in MTF at Nyquist for increasing wavelength following the expected trend for decreased resolution with increasing wavelength resulting from the fixed effective aperture of the Mastcam-Z cameras