If you are researching ancestors who lived in California 1769-1850 and don't know about this online searchable database, you should investigate it. The URL is http://www.huntington.org/Information/ECPPmain.htmhttp://www.huntington.org/Information/ECPPmain.htm. The ECPP database is a comprehensive compilation of baptismal, marriage and burial records from each of the California missions and the Presidio of Santa Barbara. Access is free and there is a user guide with instructions and sample searches.
I was able to confirm my ancestry back to Jose Francisco de Ortega using information from ECPP that I had been unable to locate anywhere else. Happy hunting!