The magnitude system is defined so that a difference of five magnitudes is precisely a 100 times difference in brightness. In short, there is no definitive advantage in getting one of these over the others. This represents just about the absolute limits of human vision from dark sites here on earth, although some have claimed to see 7th mag visually from waaaaay out in the middle of nowhere. Whoops! >>That’s the difference between Sirius at -1.46 and Shaula, the bright star in Canis Major forming the dog’s rear leg, at 1.50. I have an 8se that never gets used though, mainly due to the fact that I prefer the simplicity of the dobsonian. Yeah, this is part of the solution for bigger scopes like that. If not, well . The optical quality is the same as any other 8″ Dob, but the whole package is so much better than the other 8″ models they are not even close to the Z8. It looks like the AD8 is available here - I will be using this while camping in the mountains, so clear skies with very low light pollution. Point sources are stars, double stars, open clusters, and to some extent, globular clusters. It’s not for me because I’m already deep into middle-age, I’ve always been a deskbound nerd, I never work out, I’m outta shape, and as weak as I am now, I want a scope to last me for the rest of my life, not something I’ll use as a gym substitute. Remember how heavy it was? This is based on the severity of the other four factors beyond the first one:  maybe your optics are collimated well, but not perfectly; your optics aren’t as clean as when they left the factory, or maybe you scratched ’em up a bit the last time you cleaned ’em (oops); your aging eyes just ain’t what they used to be, etc. But if you’re observing from a decent dark site that’s only 5th mag visually (remember, that’s actually 5.49), that extra 7 mags only gets you to 12.5. The Skyline has great accessories, in the same league, but I understand if you feel that it's overpriced. If you drive to a dark site a few miles out into the boonies that lets you get to 5th magnitude visually (actually 5.49), there are now 2800 stars total you can see. Because the brightness increases logarithmically, 2 magnitudes difference, which is the difference between Vega (0.0) and Polaris (2.0), is 2.512 squared = Vega is 6.3 times brighter. You’re observing from a truly dark site that lets you get all the way down to 6th magnitude, no humidity or water vapor, and no dust or other particulates in the air (smog, wildfires) to diminish that; Your optics are collimated perfectly, so that all the light is getting to your eyeball, and there’s no stray light entering the tube from off to the side of what you’re observing to diminish contrast; There are no scratches or significant dust on any of your optical surfaces that would diminish or scatter light; in other words your optics are practically pristine; Your eyes are in excellent shape – no astigmatism or other visual aberrations (other than near- or far-sightedness; the scope acts as your glasses in those two circumstances), you don’t have cataracts or yellowing of your eye lens, your pupils dilate nice and wide; you have all the rods you’re supposed to have on your retina to detect light under low-light conditions, meaning, you’ve eaten all your carrots so that your night vision is good. An 8-inch scope, under those nice dark skies I described above, with an observer who’s got good eyesight and all, will let you see down to 13.5 magnitude. Change ), You are commenting using your Google account. Fixed, and thanks for pointing out my errors, I appreciate it. The aphorism is really, “Get the largest scope you can both afford and move around easily.” I don’t think the heavier 10-inch falls into that category for a lot of people. . Change ), Jon is a former attorney who formerly lived in Manhattan, who enjoyed using his 5-inch Mak there under the world's worst light-polluted skies. ( Log Out /  Apertura AD8, HighPoint DT8, and Zhumell Z8 are all currently unavailable. I read the sticky, but unfortunately 3 of the recommended 8" are unavailable. Others have disagreed with me that the reduction is as severe as this. It looks like the finder scope is a pricy one, as getting the Skyline's is about $100. The choice between Dobsonian models is usually based on the accessories bundled with it. You’ve got Castor and Pollux right next to each other as the heads of the twins. That’s almost 6 gallons of milk in that box. Fourth mag skies really means 4.49 mag skies, not 4.00 skies.) The XT10 is a total of 53.4 lbs., with the tube being 50% heavier than the XT8 at about 31 lbs., and the remaining 22 1/2 lbs. Adhara is in Canis Major.