The SkyQuest XT is available in 4.5 inch, 6-inch, 8-inch, and 10-inch versions (a 12 inch model is also available, but it’s expensive and much less popular). Size Matters. The Orion SkyQuest XT Range: Superb in All Ways Except One. Planetary detail is SkyQuest XT6’s strong suit. I can’t say that it was a single moment or event that sparked my interest in astronomy. But something clicked in my head a few summers back, that inspired me to buy my first telescope and reveal the wonders of the night sky. The Orion SkyQuest XT6 Classic Dobsonian telescope is a very good 6 inch Dobsonian telescope to invest in with a good quality build, great specs, decent accessories bar the finderscope and of course the great price of around $250 – $300. ... XT4.5, XT6, XT8, or XT10? Jupiter’s The Great Red Spot, 4 Galilean Moon’s and its many stripes are easily visible with Orion SkyQuest XT6.. Orion ® SkyQuest ™ IntelliScope ™ XT6, XT8, XT10 #9816, #9918, #9950 . 2 Figure 1.The SkyQuest XT8 IntelliScope Secondary mirror holder with 4-vane spider (not visible) Finder scope Finder scope bracket Eyepiece Focuser Optical tube Tensioning knob IntelliScope Controller Port modular jack Primary mirror cell It easily extracts detail from Jupiter, Saturn, Mars, Venus and the Moon. The Orion SkyQuest XT6 and XT8 differentiate in one main way – the XT8 has a 8″ (203mm) diameter parabolic primary mirror compared to a 6″ (15mm) diameter parabolic primary mirror, meaning they provide different light gathering abilities. My First Telescope – The Orion Skyquest Dobsonian.