Like the KRON and JOHN filters, Sloan filters are used to filter out and measure specific bands of light that are emitted by astronomical objects. The difference between SDSS filters and the KRON and JOHN filters is that they are non-overlapping and have steeper transitions between bands.
The Sloan bands are U, G, R, I, and Z. Refocusing is always a problem when changing filters. Andover can minimize this problem by grinding and polishing all filters to a very precisely controlled specified thickness. These filters are also AR coated to provide optimal performance and better imaging. Sloan Digital Sky Survey has created a detailed three-dimensional map of the universe using these filters. (www.SDSS.org)