== '''Red prism''' ==
The table and plots on this page can be used to determine the prism position to useto cover a desired wavelength range. The table gives the first and last orders and the wavelength range for each prism position. There is likely an uncertainty of +/-1 order, and +/-2 for the points that don't quite fit the trend in the plots below (these odd points are due to having to initialise the prisms between measurements)orders.