A: As mentioned earlier, these filters are critical for proper measurement. The user manual explicitly defines that these controls set the cutoff wavelength for the roughness filter. "Filter 1" is likely the standard filter (Gaussian), while "Filter 2" might be a different type or a 2CR filter (an older standard). In the SV-400's generation, these physical switches were the primary way to select the measurement standard (e.g., JIS 1982, JIS 1994, ISO 1997).

The Surftest SV-400 is featured in credible research, demonstrating its role in industrial and academic metrology:

If you need help configuring specific settings on your machine, please let me know: What you are trying to calculate (