Appellant was found to have violated his probation by violating Penal Code section 311.11, misdemeanor possession of images , the production of which involves the use of a person under the age of 18 personally engaging in or simulating sexual conduct, with knowledge the person is under 18. The court rejected his argument that the statute was unconstitutional, and distinguished The Free Speech Coalition v. Janet Reno (9th Cir. 1999) 198 F.3d 1083, on the ground that the Reno case involved criminalization of the images of fictitious children. The California statute requires a real minor under the age of 18. The court concluded that expert testimony on apparent age is admissible. Here a pediatric nurse practitioner testified as an expert witness that several of the individuals in the video clip appeared to be under 18, based on physical development. Apparent age and actual appearance are simply forms of evidence allowable for proof of the fact that the individual depicted is actually under the age of 18. Finally, defendant’s own statement that he believed the individuals were under 18 was sufficient to show his knowledge by a preponderance of the evidence in the probation violation hearing.