Galaxies (and planetary nebulae) in general demand very long focal lengths, but M31 and M33 are fair game for camera lenses. This is the longest focal length, ultra portable, set-up I own. All the equipment required (mount, tripod, counterweight, OTA, camera, programmer/timer, plus all batteries for camera and mount, add up to under 10kg. The whole lot fits into an airline carry-on.