The short(er) version is this: It depends on whether you want to get the max out of any given configuration. Once you maximize light gathering capability you work on contrast gain - and the best way to do that is reduce reflected light internally. Baffles are a way to conteract the fact that no surface is completely non-reflective, so you install a baffle which gives that reflected light something to run into on its way to your eyepiece. Like so: (rough examples only, I'm short on time) If you took a thin sheet of something (wood?) and cut a whole in it 1/2" larger diameter than your primary, and mounted it in the scope 1/2" ahead of the first surface of the primary, then it helps to shut down on light striking the mirror which wasn't actually on your desired path - just managed to bounce it's way down the tube. You can then put another, maybe 1" larger diameter hole a couple inches further up, and another and another as you choose - always increasing the aperature as you move toward the front of the scope. The end result is that light incoming has to be in the desired 70% path (or better, your choice) so it's actually from your object. Similarly, whatever else is in there beats itself against the baffles and never makes it to the eyepiece - hence dark is darker and your image is brighter. Are they worth it? Yes, done right they can help. Is it awesome? No, but it can make a difference. Its not as extreme by far, but can be compared to using a truss tube scope without the shroud... background is grey instead of black - see? Hope that helps. Finally, there's a calculator on the net that helps do some of these sizes for a given configuration - its called Newt20. Don't recall the address, try a search for it?