The Mars Science Laboratory Mast camera and Descent Imager investigations were designed, built, and operated by Malin Space Science Systems of San Diego, CA. They share common electronics and focal plane designs but have different optics. There are two Mastcams of dissimilar focal length. The Mastcam‐34 has an f/8, 34 mm focal length lens, and the M‐100 an f/10, 100 mm focal length lens. The M‐34 field of view is about 20° × 15° with an instantaneous field of view (IFOV) of 218 μrad; the M‐100 field of view (FOV) is 6.8° × 5.1° with an IFOV of 74 μrad. The M‐34 can focus from 0.5 m to infinity, and the M‐100 from ~1.6 m to infinity. All three cameras can acquire color images through a Bayer color filter array, and the Mastcams can also acquire images through seven science filters. Images are ≤1600 pixels wide by 1200 pixels tall. The Mastcams, mounted on the ~2 m tall Remote Sensing Mast, have a 360° azimuth and ~180° elevation field of regard. Mars Descent Imager is fixed‐mounted to the bottom left front side of the rover at ~66 cm above the surface. Its fixed focus lens is in focus from ~2 m to infinity, but out of focus at 66 cm. The f/3 lens has a FOV of ~70° by 52° across and along the direction of motion, with an IFOV of 0.76 mrad. All cameras can acquire video at 4 frames/second for full frames or 720p HD at 6 fps. Images can be processed using lossy Joint Photographic Experts Group and predictive lossless compression. Key Points The Mars Descent Imager, an f/3 9.7 mm, 2 M pixel color camera operated autonomously during landing taking a descent video at 4 frames/second Mastcam‐34 f/8, 34 mm camera takes <1600 × 1200 pixel images in broad and narrowband color over a field 20° × 15° at a scale of 218 μrad/pixel Mastcam‐100 f/10, 100 mm, f/10 takes <1600 × 1200 pixel images in broad and narrowband color over a field 6.8° × 5.1° at 74 μrad/pixel scale Plain Language Summary Paper describes the Mast cameras and Descent Imager on the Mars Science Laboratory Curiosity rover. Cameras take 2 megapixel color images that can be compressed in both JPEG lossy and predictive lossless format. One of the two Mastcams has a 34 mm lens, equivalent to a consumer camera 35 mm lens, and the other has a 100 mm lens, similar to consumer camera telephoto lens. The descent imager has a very wide angle lens (~90°) and takes wide angle pictures. The Mast cameras are mounted on an azimuth elevation mast so they can scan around the rover and into the sky. The Descent camera always points down. The Mast cameras have different filters to allow for scientific color imaging as well as standard color imaging as performed by consumer cameras.