Celestron’s PowerSeeker 127EQ is the perfect example of why our website exists, and why some Amazon reviewers are not knowledgeable enough to review complicated telescopes.
The PowerSeeker 127EQ is possibly the worst telescope I’ve seen amateurs recommend frequently, probably because they see its specs and think it’s a great deal.
But specs aren’t everything, and in actual use the PowerSeeker 127EQ is so horrible, that I considered not buying anything from Celestron ever again. Celestron mentions that this scope can achieve up to 450 power, which is too high for a 5ʺ telescope, or any telescope. An advertisement like that should be an immediate red flag for anyone looking to purchase a decent telescope.
If this information hasn’t convinced you already not to buy a 127EQ, read on.
Overview Of Powerseeker 127EQ
The 127mm Bird-Jones Optical Tube
The 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 127EQ’s tube is only twenty inches long – 500mm. How does one fit a Newtonian optical system (not a Cassegrain, which folds the light path into a smaller physical package) into that small of a tube?
The answer is that the 127EQ 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 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 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 127EQ’s corrector is just a Barlow lens inserted into the focuser drawtube – not a proper corrector lens. It doesn’t fix the spherical aberration inherent in the roughly f/3.5 spherical primary mirror. It makes the light cone a little steeper, which in theory would correct the system to maybe half a wave – bad at half the tolerance required for a good telescope, but somewhat usable. But due to the positioning of the corrector, this isn’t possible.
To make matters worse, the PowerSeeker 127EQ’s primary mirror isn’t even a precise sphere, it’s a random shape that came straight out of the polishing machine.
The 127EQ primaries I’ve tested have had rough surfaces, really weird shapes, all sorts of microscopic holes and hills which damage the image, and 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.
Thanks to the corrector lens being permanently installed in the focuser, the 127EQ is extremely difficult to collimate.
You can remove the corrector and collimate it with a laser or the like, then re-insert the corrector, but this is a complicated procedure and heaven help you if you need to collimate it in the field. You’d think that the inability to collimate the scope would be the final nail in the coffin for the 127EQ delivering a decent image, but no…
Problems With Accessories
Normally I don’t have much to say about a telescope’s accessories as they are typically functional at the very least. But the 127EQ’s are of note because they’re so bad.
For low power, the 127EQ comes with a 20 mm erecting eyepiece. Apparently, you’re supposed to look at terrestrial objects with an equatorially-mounted Newtonian, because that makes sense. Aside from the utter bizarreness of doing so (a dedicated spotting scope is far superior), the eyepiece will be at extremely awkward angles and an equatorial mount is very difficult to maneuver to point at terrestrial objects. Putting that aside, the 20 mm eyepiece is made of plastic, and the apparent field is something like 30°. The erecting optics absorb a good chunk of the light going into the telescope. It feels like I’m staring down a soda straw!
For high power, the 127EQ comes with a 4 mm Ramsden. The last time a Ramsden had any place in the amateur astronomer’s eyepiece box was the 1960s, when a Kellner or Orthoscopic was rare and sought after. This was when most people were using 4ʺ reflectors and 60 mm refractors as serious observing tools.
The 4 mm Ramsden has a tiny eye lens, provides basically the maximum power a good 5ʺ can take (250x), and the field of view is under 40°. Again, it’s like looking through a soda straw.
It also throws up so many aberrations that even if the aforementioned issue wasn’t, it’s basically unusable. A beer bottle would make a more effective eyepiece.
The 127EQ comes with a 3x Barlow lens made of plastic to achieve the 450x magnification that’s advertised on the box. It probably costs fifty cents to make and has the optical quality of something you’d find in a cereal box. Need I say more?
The 127EQ’s finder scope is a 5×24 with plastic lenses and an internal aperture stop, making it slightly more effective than sighting down the tube.
About The Mount
The 127EQ’s mount is actually a decent EQ-1 mount. It’s almost made entirely out of metal and capable of holding the 5ʺ OTA to some extent, though a more stable mount would be better. Unfortunately, it could be the best mount in the world but still not make up for the flaws of the telescope itself.
What's The Bottom Line?
Do you want to know how bad the Powerseeker 127EQ is?
I spent a few days doing everything possible to get my 127EQ to work. I’ve owned dozens of telescopes. I’ve serviced hundreds. I know what I’m doing, and after all my efforts I was still presented with images worse than any telescope I’ve ever looked through.
There are better options than the Celestron PowerSeeker 127EQ in its price range. There are better options than the 127EQ well below its price range. Please don’t buy this telescope for yourself or anyone you know. If you’re given one, save the mount and haul the tube and accessories to the trash.