I just learned how to use the multiple exposure settings on my Canon 5D Mark iii. This is a double exposure. Took a picture of the moon with my 500mm followed by a picture in the backyard at 24mm. The camera averages out the two photos. Nice feature I plan to use more often,
2 exposures (1) 1/800th sec 500mm, 20 sec 24 mm, ISO 320