Hi All, Bit of a long reach/split question here... Had a DSLR for 8 years, and recently upgraded to a 70D, and rediscovered my love for taking pictures of pretty things. I've got a couple good lenses already: 50mm F1.8 Prime (Captured this timelapse in London with it! https://www.youtube.com/watch?v=oAXUGaV9yto) 18-135mm F3.5-5.6 STM 55-250 F3.5-5.6 STM 500mm Mirror (great for moon shots) I'm looking for a good telephoto lens with a fast aperture that's not going to break the bank for some astro photos, any recommendations? To go alongside the lenses, it's apparent that i'll need me a decent (cheap) tracking mount. I'd researched some of the options and this seems to fit my budget/mindset: http://www.garyseronik.com/?q=node/52 However, I lack the resource to build one - any bit-techers out there want to be commissioned into constructing this piece of kit?