Two executives of a Chatsworth production company that defrauded hundreds of investors were sentenced on Monday to federal prison terms. Christopher Blauvelt, 59, a former Woodland Hills resident, and David Pritchard, 67, of Hollywood, collected $21 million from investors by promising large returns on movie investments through a company called Gigapix Studios, according to the U.S. Justice Department. The pair claimed to be producing a 3D animated version of the “Wizard of Oz,” while also touting an imminent and profitable public offering, prosecutors said. Roughly 730 people lost virtually all of the money they invested in Gigapix and the film, “OZ3D.” United States District Judge Manuel Real sentenced Blauvelt on Monday morning to eight years in prison; Pritchard was sentenced to five years. The men were convicted at trial last year on a series of federal charges, including mail fraud, wire fraud and offering for sale unregistered securities. Blauvelt founded Gigapix in 2002, taking on Pritchard as a partner in 2006. Pritchard hired telemarketers to solicit potential investors, who were told that Gigapix was a financially successful company, that the investments carried little or no risk and that there was an urgency to invest in Gigapix and “OZ3D” because the window of opportunity to invest and the number of shares available were limited. Investors were also told that a minimum of 65 percent of the money invested in “OZ3D” would be used to produce and distribute the movie. Less than 5 percent of the investors’ money was actually used to finance the film, according to the Justice Department.