OK, here is the Bible according to Celestron SLT scopes. When the scope is working, it's fantastic (see below if you have a non-working scope with a boot loader failure). The Newtonian design is comfortable to look through - the eyepiece is at the front of the scope, and it is positioned around eye-level when standing. Newtonian optics are also simple, which keeps the cost down (and minimizes light lost to lens absorption). The optic properties of this scope are outstanding. The 650mm focal length and 150mm (about 5-1/8") aperture are great specs, especially when paired with the highly-recommended Celestron accessory kit (Celestron Model 94303, available on Amazon). The scope comes with a 9mm and 25mm eyepiece, for magnifications of 72 and 26 power (magnification is focal length divided by eyepiece length, so magnification increases as focal length increases, and decreases as eyepiece length increases). The big 130mm aperture of this scope gives the scope a maximum useful magnification of about 307 power, using the rule of thumb that you can magnify 60 times for each inch of aperture. At a focal ratio of f5, this is a fairly "fast" scope, meaning it lets in a lot of light for it's focal length. The f-number is the focal length divided by the aperture size, and the lower the f-number, the faster the scope. Faster is (generally) better. F-numbers will be familiar to photographers, and telescopic "lenses" operate on the exact same concept as fast photographic lenses. In photography, a lens is "fast" because it allows a shorter shutter speed (because it lets in more light), meaning you can capture faster motion that would be blurry with a longer exposure (as would be required by a "slower" lens). The auto-orientation works like magic, but it's better to give it very precise time and location. Use a GPS for location; don't just tell it what city you are in (you can choose your location input method). For some reason, the controller can remember your last location and the time zone of your previous observation, but the controller does not keep time when it is switched off, so you must enter the (exact) time again whenever you switch the power off and back on (C'mon, Celestron - seriously?) You can orient the scope by pointing the scope at ANY three bright objects (you do not need to know what they are) or two objects if you know what they are (but this is said to be less precise). The scope must be level (it has a built-in level bubble). Although this scope is not really classified as a "beginner's scope," it is great for beginners - you don't need to know anything to begin viewing amazing things, and a beginner will not "outgrow" this scope anytime soon. The only comparable computerized Newtonian scope that I could find in this price range is the Orion StarBlast 6i IntelliScope, but it is available only with a table-top mount (???). If that Orion scope (750mm focal length, 6-inch aperture) was available with a sturdy tripod mount in this price range then I would be writing this review for that scope, because I would have bought that scope instead, without a doubt. Orion lost my business because they expected me to have a study TABLE available at each observation site. The optional Celestron accessory kit includes (among other things) 6mm, 8mm, 13mm, 17mm, and 32mm eyepieces and a Barlow 2X adapter. With a 6mm eyepiece and a Barlow 2X adapter (which effectively doubles the magnification of the eyepiece, making it a 3mm focal length), the scope can achieve a magnification of 216 power (pretty respectable). You could purchase shorter eyepieces or a 3X Barlow to push the magnification near the 307 power limit, but I don't think you will find yourself wanting to do so - you will be amazed at what you can clearly see (the bands of Jupiter and its Galilean moons, the rings of Saturn, etc). Note that the 307-power limit cannot be exceeded with eyepieces or Barlow lenses - the image will be pretty much worthless if you try to exceed this limit, which is a function of how much light the scope can gather (which is determined by the aperture size). As you approach this limit, the image quality decreases, so you will probably find images much more satisfying at low-to-mid-200 power than you would at theoretical maximum 300+ power. The gray moon filter in the accessory kit is especially useful for bright objects (such as the moon, of course, but also Venus and Jupiter). The longer eyepieces are needed for viewing large objects such as various asterisms, galaxies, and nebula. Some of these objects span 2 or 3 degrees of sky (or more) - which is really big (the sun and moon are 0.5 degrees.) Some objects can only be fully viewed at very low magnification (such as afforded by binoculars), so don't make the mistake of assuming that high magnification is always better. If you attend a star party, expect to find binoculars (usually mounted on a tripod) in use. The Pleiades star cluster, for example, is best observed at lower magnification. The eyepieces that come with the scope (and the accessory kit) are 1.25" diameter, but the scope can also accept large, very nice (and expensive) 2" eyepieces - just remove the 1.25" adapter which comes with the scope. The tripod mount is good, but will wiggle a bit in the breeze, especially at higher magnifications. It helps to add some weight - the tripod has a small shelf which lends itself to this purpose. A couple bags of rice or beans will do, but I bought a 20-lb theatrical-grade sandbag (double zippers keep sand out of my optics, and sand doesn't attract bugs or rodents). Put that weight on your tripod and don't touch the scope while viewing (take your hand OFF of the focus knob) and you should have a steady view, even in breezy conditions. Stiff winds may require additional measures, such as springs attached to the legs and anchored to stakes in the ground. I was told by someone at a Star Party that this mount is not well suited for long-exposure deep-field photography. As it tracks objects across the sky, the mount makes slow adjustments, but it does not adjust azimuth (side-to-side) and altitude (up-and-down) at the same time, but in succession, in a stair-step pattern. The eye won't notice, but a long-exposure photo will see blurring. Alas. But I have not verified this info. In any event, it should work fine for short-exposure shots, like the moon (you will need a camera adapter, of course). The motorized mount goes through batteries pretty fast, especially if it is tracking something all the time. The default power source of eight (standard alkaline) AA batteries will probably last a night, but I would not push it to two nights if I had been tracking the whole night before. You can hook it up to a car battery and it will run forever. I use a wheelchair gel battery - they are smaller and lighter than car batteries, and will take the deep-cycle use (charge and deplete, charge and deplete). Buy a trickle charger and use it when the battery is not being used, to keep the battery fresh and extend its life. Or you can get the Celestron Power Tank. You can use an AC adapter if you have access to AC - any adapter that puts out 12 volts DC at 2.5 amps or more with a 2.5mm barrel plug (negative on outside, which is standard) will work just fine (you can have all the extra amps you want - it won't hurt anything). There are scads of suitable adapters on Amazon that are a whole lot cheaper than the one Celestron sells. This is a Newtonian scope, and Netownians are subject to collimation errors, meaning that the two mirrors are not precisely aligned. I recommend the Celestron Collimation Eyepiece (Celestron Model 94182, available on Amazon). This will allow you to quickly and easily (and accurately) calibrate your scope for an absolutely perfect image. Some people do this each time they transport their scope, because any sort of vibration can cause the mirrors to drift (though it seems to be a rather minor problem for this sc
