The 42nd annual RTMC Astronomy Expo took place in Big Bear City, California, from Wednesday, May 12 to Sunday, May 16, 2010.

RTMC stands for the Riverside Telescope Makers Conference and was founded in 1969. This year's theme was Dark Sky Observing.

The Imaging Source' American resellers Opt Telescopes and Woodland Hills cameras went there with The Imaging Source Astronomy Cameras.