Overview Of The 127mm Bird-Jones Optical Tube
The Celestron PowerSeeker 127EQ is a 127 mm 5ʺ f/7.87 (focal ratio) Newtonian with a focal length of 1,000 mm. If you do some basic math, you’ll immediately notice something odd. The PowerSeeker 127EQ’s tube is only twenty inches long – 500mm. How does one fit a “Newtonian” optical system (not a Cassegrain, which actually “folds” the light path into a smaller physical package) into that small of a tube?
The answer is that the Celestron PowerSeeker 127EQ is not a Newtonian. It’s a Bird-Jones. Bird and Jones were two amateurs in the 1950s who sought to create a simple telescope with a spherical instead of a parabolic primary mirror, with a corrector lens/Barlow in front of the secondary mirror. This design, in theory, can work well, and some properly executed Bird-Joneses do in fact work quite well. But the Celestron PowerSeeker 127EQ is anything but properly executed.
Unlike the classical Bird-Jones style, which puts the corrector lens just in front of the secondary mirror, the 127EQ’s “corrector” is mounted in the focuser. This means that it will move whenever you dial in the focus, thus assuring the correction is basically never spot-on.
Even if the corrector being mounted in the focuser was not an issue, the Celestron PowerSeeker 127EQ’s corrector is just a Barlow lens inserted into the focuser drawtube – not a proper corrector lens. It doesn’t actually fix the massive amounts of spherical aberration inherent in the f/3.5 spherical primary mirror, which by default should prevent the telescope from forming a sharp image at even very low magnifications. Rather, the corrector-Barlow simply makes the path of the light rays through the telescope a little steeper, which in theory might be enough to provide a pretty decent – if not the sharpest – image. But due to the constant displacement from its ideal positioning thanks to being mounted in the focuser, the 127EQ’s corrector at best enables the scope to deliver images that are barely acceptable for a telescope of its size and price. At worst, the views are a completely mushy, unusable mess.
To make matters worse, the PowerSeeker 127EQ’s primary mirror isn’t even a precisely manufactured sphere; it’s a random shape that came straight out of the polishing machine. The PowerSeeker 127EQ primaries I’ve tested have had rough surfaces and all sorts of microscopic holes and hills that damage the image, as well as many other complicated flaws. These are all caused by the fact that nobody actually bothers to test these things before throwing them in the telescope. If Celestron performed any quality control on the PowerSeeker 127EQ, after all, it might not have been created in the first place. The primary mirror also appears to be secured to its support with solid gobs of epoxy, which warp and distort the mirror due to the stress they induce on the glass. This further hinders the already-low capabilities of the telescope.
The Celestron Powerseeker 127EQ is rather difficult to collimate with the corrector lens in the focuser, as the corrector makes the reflected image of the primary and secondary mirrors look rather tiny. The corrector lens also inhibits the function of a laser collimator. Thus, to collimate the 127EQ, you must first remove the corrector lens, which requires taking apart the focuser, carefully unscrewing the ring that holds the corrector, and avoiding getting fingerprints (or grease from the focuser drawtube) on the corrector lens, then re-assembling the focuser temporarily to collimate. After collimating the scope, you then have to take the focuser apart again, re-install the corrector, making sure to put it in the right way, and then re-assemble the focuser. In addition, the collimation screws on the Celestron PowerSeeker 127EQ have next to no travel and are easily stripped. Collimating the 127EQ was hard enough for me to do in the shop; a beginner attempting it out in the cold and dark will find it impossible.
Problems With Celestron Powerseeker 127EQ Accessories
If you thought the Celestron Powerseeker 127EQ’s optics were bad, the eyepieces are actually worse by every stretch of the imagination.
The low-power eyepiece included with the 127EQ is a 20mm Kellner with a permanently installed “erecting prism to flip the image right-side up, and it provides 50x. 50x is a bit of a high magnification for “low power” with a 5” telescope, especially one with poor optics. The erecting prism is included so that Celestron can claim the telescope is capable of terrestrial viewing, and it comes at the expense of sucking up quite a bit of the light entering the telescope, blurring the image due to its extremely low quality and providing a field of view reminiscent of a drinking straw. As a result, you’ll struggle to locate targets (a problem worsened by the next-to-useless included finderscope) or fit them into the field of view.
For high magnification, the 127EQ comes with a 4 mm Ramsden. The last time a Ramsden had any place in an amateur astronomer’s eyepiece box was in the 1960s, when a Kellner or Orthoscopic was rare and sought after. Like the included 20mm eyepiece, the 4mm Ramsden has a tiny field of view. Worse, however, it has a tiny eye lens and next to no eye relief – meaning you’ll need to jam your eyeball into it to see much of anything – and provides 250x, which is too much for even a quality 5” telescope (which the 127EQ is a far cry from). It’s also generally low quality and would provide a mushy image anyway even if there were not too much power for the scope to handle.
The included “3x Barlow” is a plastic-lensed abomination that exists to provide the “450x” Celestron claims the telescope is capable of (in actuality, very few telescopes are capable of, let alone used at, 450x). It is completely useless and should be discarded.
For a finderscope, the Celestron PowerSeeker 127EQ comes with a 5×24 unit with a single plastic lens and a plastic eyepiece. The lens is stopped down to an aperture of less than 10 mm in order to provide a usable image, depriving it of light-gathering power. The bracket is also next to impossible to align with the telescope, meaning that the finder is almost always pointed askew and thus completely useless. You’re better off removing the finder itself and using the bracket as a peep sight.
About The EQ-1 Mount
The EQ-1 mount provided with the PowerSeeker EQ telescopes is actually fairly respectable in terms of build quality and operation. However, it is completely incapable of supporting a telescope as large as the Powerseeker 127. Not only is the mount incredibly wobbly with the 127mm optical tube placed atop it, but the included counterweight is literally not heavy enough to balance the telescope. As a result, when operating the 127EQ, you have to always lock up the mount axes somewhat to prevent the whole telescope from moving around of its own accord, thus also guaranteeing that motions will be jerky and less-than-smooth as you move the telescope around the sky, exacerbating the stability issues we’ve already mentioned. Between these issues and the terrible included finderscope, it is hard to get the 127EQ pointed at pretty much anything besides the Moon.
Should I buy a Used PowerSeeker 127EQ?
No, not even for $1.
At the same price as the 127EQ, and even well below it, there are a lot of telescopes that will beat it in almost every conceivable way, providing sharper and brighter views, sturdier mounts, and an overall more enjoyable user experience.
- Zhumell Z114: Tabletop Dobsonian mount provides ease of pointing and maximum stability. Great optics and decent accessories.
What can you see with the Celestron PowerSeeker 127EQ?
The Celestron PowerSeeker 127EQ’s low-quality optics are a permanent handicap, even if you upgrade the accessories. If you can manage to get the scope collimated and deal with the frustration of aiming it, expect to see the following.
- Mercury – An ill-defined smudge. It’s unlikely you’ll be able to resolve its phase.
- Venus – The phase is easy to see, albeit with a lot of glare surrounding the planet caused by the corrector lens and low-quality eyepieces.
- The Moon – A fairly decent view, but nowhere near as detailed as the sights delivered by a telescope with quality optics.
- Mars – An ill-defined blob even when it’s close to Earth. You might just be able to make out an ice cap and maybe a dark smudge.
- Jupiter – The moons are obvious (but then again, they’re obvious in a pair of cheap birding binoculars too). The two equatorial cloud belts are visible, albeit low in contrast. The Great Red Spot, normally a pretty easy catch with a careful eye and almost any half-decent telescope, is not sharply defined enough to spot.
- Saturn – The rings are visible, though fuzzy, and maybe a couple of moons can be spotted. The Cassini Division in the rings cannot be seen, and you won’t be able to glimpse any of Saturn’s fainter moons besides Titan and Rhea.
- Uranus and Neptune – Assuming you can even find them, the PowerSeeker’s optics are bad enough that you can’t distinguish either planet as a clear disk.
Many of the most exciting star clusters are visible, but lack crispness.
Emission nebulae: The Orion Nebula looks okay but the Trapezium star cluster is mushy. The Lagoon is a wispy cloud, with bloated, ugly stars inside it. The Swan is ill-defined.
Galaxies are troublesome to find and lack anything resembling detail.
Forget most planetary nebulae; they’ll be blurred beyond recognition.
Splitting any remotely close double star with the 127EQ is impossible.
Pricing and Availability
The price of the scope was roughly $130 when this Celestron PowerSeeker 127EQ review was first published in 2019. However, the price has since skyrocketed. On Amazon, the scope is frequently available, with many of the listings coming from pricey third-party dealers. For the most up-to-date retail pricing, go over to the HighPointScientific listing (*not an affiliate link).