Orion XT4.5 has the potential to become a disappointing purchase or telescope that you will use for a lifetime. This scope has unique ergonomics and optics, so you have to be careful about what you are getting with XT4.5.
The most separating factor of Orion XT4.5 is its optical tube length. It is 900mm, which is around 35.4 inches. This optical tube length is particularly long for a reflector that has a 114mm(4.5″) aperture, and this is purposely done by Orion. The reason is that the primary mirror of XT4.5 is spherical and not parabolic.
If you are a beginner, you probably don’t know what this means. In short, a spherical mirror is low-quality, and a parabolic mirror is high-quality.
To reduce the problems that come with a spherical mirror, Orion lengthened the optical tube to an unusual level. The resulting optical quality is surprisingly good, and it turns out this type of optical design has serious advantages.
The optical tube is unusally long.
Advantages of a Long Optical Tube
Firstly, the brightness and contrast levels are no less than any other 4.5″ telescope, if not better.
Secondly, the planetary performance of this telescope is exceptional for this price range. The long optical tube increases the ability to focus at high magnifications, therefore getting some detail from objects such as Jupiter, Mars, and Saturn is effortless.
Thirdly, the collimation process is much easier. Collimation is an alignment process you regularly will have to do, and thanks to the 900mm tube, it is much easier than other reflectors.
Disadvantages of a Long Optical Tube
The main disadvantage is the narrow field-view. Finding the object you want to observe in the night sky is not easy with Orion XT4.5, especially with the low-quality finder that comes with it.
The narrow field view also lowers the quality of deep space observations. Although sharpness and brightness are on point, remarkably large star clusters, galaxies, and nebulas are not as pleasing to observe as other Dobsonians.
Overall, although the primary mirror is spherical, the optical performance is pretty good. If you are going for some planetary and Lunar detail, XT4.5 is a no-brainer. But keep in mind there are some sacrifices made in the deep space performance area.
The mount has an altazimuth design. It only moves up, down, left, and right, and the motions are smooth. The base is solid enough to carry the optical tube, and the springs attached help with friction adjustment.
The base is well-built.
Overall the mount is pleasing and doesn’t bring up any complaints. A Dobsonian mount is hard to screw up anyway.
Ergonomics of XT4.5 is another factor that makes it unique. As I’ve mentioned before, the optical tube is 900mm(35.4″) long, and the eyepiece is located at the top. So as you might understand, you will have to bend down to observe, or you will have to lift the scope up.
You can easily solve this problem with a stand or table that is at the proper height. But keep in mind that you will have to carry this object wherever you go observing.
By the way, although this is a problem for adults, it is an advantage for kids. They will have much of an easier time observing since they won’t have to bend down all the time.
The eyepieces that come with Orion XT4.5 are surprisingly good. They are high-quality Plössl’s and have 25mm and 10mm apertures. The 25mm eyepiece provides a wide-field, 36x image, which is ideal for deep space observations. The 10mm eyepiece provides a narrow, 90x image, ideal for planetary detail.
The finder is hard to use.
The finder is especially important with Orion XT4.5 since it is hard to find objects with these optics. Unfortunately, because of that, the 6×26 finder is even more disappointing. It is hard to use due to the small lens and fuzzy image quality. A red dot finder would have been much better.
The focuser is mostly plastic, but it doesn’t bring up any problems in terms of smoothness and stability. I am OK with a plastic focuser instead of a metal one as long as it drives the price down.
Finding and focusing on the objects is especially hard with Orion XT4.5, and this is enhanced by the low-quality finder. This is the most serious problem you will have with this scope.
The 900mm(35.4″) optical tube length is not for everyone. You will always need an additional base for this scope. It is ideal for kids, though.
The deep-space performance of Orion XT4.5 is especially low due to its narrow field view.
Orion SkyQuest XT4.5 is not for everyone. It is one of the go-to’s in terms of planetary and Lunar performance, and the build quality is as good as it gets. But the ergonomics of the long optical tube is not pleasing if you are an adult, and the deep space performance is disappointing due to the narrow field-view.