These filters have been made at RGO from various cemented combinations of Schott glass. R W Argyle specified the combinations, which are similar to those in use at the AAT, SAAO and elsewhere. These filters are 2 inch in size, and Table B.2 shows details of these filters. Three sets exist; two sets for the ING telescopes, and one set at RGO. These filters are on the Johnson system. Nowadays, this system (for R and I) is not used very often any more, possibly because of the large sky background. At La Palma the RGO R and I are seldom used. The U,B and V filters however are not very different from U, B and V filters on other systems. See Fig 15 for the scans of these filters.
