Star-tracking camera mount: Why it works and how to build one

In this video, I explain (using a bunch of timelapses) why "polar tracker" or "star tracker" camera mounts allow you to take long exposures of the sky without streaking. I also show off my polar tracking rig, which is my most recent piece of homebuilt photography equiment. It uses a door hinge and a curved lead screw to slowly rotate the camera (approximately 0.25 degrees per minute) and eliminate streaking in astrophotogrphy images. Based on the design by Gary Seronik: http://garyseronik.com/build-a-hinge-tracker-for-astrophotography/ My parts: Motor: https://www.amazon.com/gp/product/B00B1KXV3Q/ref=oh_aui_search_detailpage?ie=UTF8&psc=1 Gears: https://www.amazon.com/gp/product/B00EPQMFWQ/ref=oh_aui_search_detailpage?ie=UTF8&psc=1 Battery: https://www.amazon.com/gp/product/B009USAJCC/ref=oh_aui_search_detailpage?ie=UTF8&psc=1 lead screw: #8 threaded rod from Home Depot Hinge: 8"x8" strap hinge from Home Depot Controller: LM317 configured as voltage source Any USB battery will work - this is just the one I have for my phone. If I re-built the design now I would probably print or lasercut the two necessary gears to save money and have more customizability. Music in this video: I dunno by grapes, is licensed under a Creative Commons: Attribution License (https://creativecommons.org/licenses/by/4.0/) Source: http://ccmixter.org/files/grapes/16626