Zhumell’s Z100 is about the lowest price telescope we would highly recommend for an adult user. It offers nearly all the features of a larger reflector except in a much smaller package and much lower price.
The Z100 is similar to the Orion SkyScanner, which we have also reviewed, but the focuser and finder are installed in more convenient positions for the user, the Z100 has a built-in handle, and the eyepieces included with the Z100 are a little higher quality.
The Zhumell Z100 Optical Tube
The Z100 is a 100mm (3.93”) f/4 Newtonian reflector. At such a fast focal ratio, you’d expect there to be coma and you’d indeed be right. It’s not noticeable with the stock 17mm and 10mm eyepieces, but with a lower magnification eyepiece like a 25mm Plossl you’ll start to spot it at the edges of the field of view.
Additionally, at f/4 precise collimation is critical for optimal performance with any reflector. Unfortunately, the folks at Zhumell have declined to offer this crucial feature and the primary mirror sits in a static, non-collimatable cell. Thankfully the scope holds collimation pretty well over time, but the lack of adjustments is mildly concerning to say the least, and be prepared for Zhumell to not be of much assistance in replacing or fixing an out-of-collimation scope.
The Z100’s secondary mirror is collimatable, but you shouldn’t ever need to touch it. The spider vanes in at least some Z100s are not perfectly aligned with the scope’s optical axis, which can result in some weird ghosting/flaring effects – however this is not guaranteed and little more than a minor nuisance when viewing bright objects.
The Z100’s focuser is a 1.25” rack-and-pinion consisting partially of plastic. It works adequately. The scope attaches to its tabletop Dobsonian mount using a short, metal Vixen dovetail.
The Z100 comes with two eyepieces: A 17mm Kellner (24x) and a 10mm Kellner (40x). These eyepieces are certainly decent (though they do lack rubber eyecups, which I find annoying) and are made entirely of metal and glass – no plastic to be found, unlike the eyepieces supplied with many cheaper telescopes. The 10mm is, however, rather short on eye relief and its short physical length may result in your nose bumping into the telescope while viewing.
The Z100 can certainly take more magnification, however, and an eyepiece like the oft-cited 6mm “goldline” (which would provide 67x) would certainly be a good addition. The scope could theoretically take up to 150-200x but in practice the complete inability of the user to collimate the scope will probably limit you to below 100x (additionally there are few good eyepieces of a short enough focal length to provide such a magnification, and even a 6mm with a Barlow is only going to give you 134x).
The Z100 also includes a standard red dot sight, which works just fine for this telescope.
The Z100 comes on a fairly utilitarian tabletop Dobsonian mount, which it attaches to via a plastic Vixen dovetail saddle. The mount is made mostly of particle board with some sort of laminate glued on, but the azimuth bearings are in fact real Teflon pads. The altitude bearing is not of the conventional Dobsonian design but works nonetheless. Additionally, the mount has a small cutout for use as a handle.
If you don’t have a sturdy enough table or bar stool to set the Z100 on, the bottom of the mount has a ¼ 20 threaded hole so you can attach it to most photo tripods.
What can you see?
The Z100 will offer great views of the Moon and decent views of Venus, Mars, Jupiter, and Saturn. Venus will show its phases, Mars its ice caps and maybe a few dark areas at opposition, and Jupiter and Saturn will show their moons and cloud belts – Jupiter’s Great Red Spot is also visible, as are Saturn’s majestic rings and the gap between them known as the Cassini Division. Uranus and Neptune are also visible as tiny bluish dots, but are a bit tricky to locate.
A small, inexpensive refractor like the Meade Infinity 70AZ may do a slightly better job on the planets than the Z100, but the Z100’s larger aperture makes it superior for viewing deep-sky objects, and it’s also far more lightweight, compact, and portable than a refractor.
Outside the solar system, the Z100 can show you thousands of double stars, hundreds of open star clusters, and a decent collection of galaxies, nebulae, and globular star clusters. However, you are mostly limited by the scope’s small aperture, lack of ability to take high magnification well, and the quality of the skies where you live.
While the Zhumell Z100 isn’t perfect, you really aren’t going to be finding perfection in a sub-$200 or even sub-$300 telescope. For the price it performs really well and a beginner will get a lot of enjoyment out of it. I would definitely recommend this scope.