Celestron’s PowerSeeker 127EQ is a perfect example of why websites like ours exist, and also of why Amazon reviewers are too incompetent to review anything more complicated than a grilled-cheese sandwich.
It’s possibly the worst telescope I see even knowledgeable amateurs recommending frequently, because they simply see its specs and think it’s some great deal. But specs aren’t everything, and in actual use the PowerSeeker 127EQ is so horrible that I contemplated never buying anything from Celestron again after using one.
Celestron mentions that this scope is capable of achieving up to 450 power, way too high for a 5” telescope (or really any under normal conditions). An advertisement like that should be an immediate red flag to anyone looking to purchase a decent telescope.
If this hasn’t convinced you already to not buy a 127EQ, read on this review of Celestron Powerseeker 127EQ.
The PowerSeeker 127EQ is a 127mm (5”) f/7.87 “Newtonian” with a focal length of 1000mm.
If you can do some basic math, you’ll immediately notice something odd about that: The 127EQ’s tube is only 20 inches long – only half a meter! 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 it’s not a Newtonian.
The PowerSeeker 127EQ is a creation known as the Bird-Jones.
Bird and Jones were two 1950s amateurs who sought to create a simple telescope with a spherical instead of parabolic primary mirror and a corrector lens/Barlow in front of the secondary mirror, which at least in theory worked 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, which put the corrector lens just in front of the secondary mirror, the 127EQ’s “corrector”, if you can even call it that, is mounted in the focuser. This means that it will move whenever you dial in the focus, which means that the correction would only be right a very small fraction of the time with a certain eyepiece and certain conditions.
Even were the corrector being mounted in the focuser not an issue, the 127EQ’s “corrector” is in fact nothing more than a Barlow lens inserted into the focuser drawtube. It doesn’t actually fix the spherical aberration inherent in the roughly f/3.5 spherical primary mirror – it just 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 this “corrector”, this isn’t possible.
To make matters worse, the PowerSeeker 127EQ’s primary mirror isn’t even a precise sphere, it’s just whatever figure it is when it comes off the polishing machine.
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 caused by the fact that nobody actually bothers to test these things before throwing them in the telescope.
Thanks to the corrector lens being more or less 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 of any hope of the 127EQ being able to deliver 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. But the 127EQ’s are of note, because they’re just so bad.
For low power, the 127EQ comes with a 20mm “erecting” eyepiece. Apparently, you’re supposed to look at terrestrial objects with an equatorially-mounted Newtonian, because that makes sense.
Putting that aside, the 20mm eyepiece has a body made entirely of plastic, the erecting optics absorb a good chunk of the light going into the telescope, and furthermore the apparent field is something like 30 degrees. It feels like I’m staring down a soda straw!
For high power, the 127EQ comes with a 4mm 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 a rare, sought-after thing and most people were using 4” reflectors and 60mm refractors as serious observing tools.
The 4mm Ramsden has a tiny eye lens, provides basically the maximum power a good 5” can take (250x), and the field of view is under 40 degrees making it once again basically a soda straw. Also, it throws up so many aberrations that even if the aforementioned weren’t an issue it’s basically unusable. A beer bottle would make a more effective eyepiece.
The 127EQ comes with a 3x Barlow lens made entirely of plastic to achieve the 450x advertised on the box. It probably costs 50 cents to make and has the optical quality of something you’d find in a cereal box. Need I say more?
The 127EQ’s finderscope is a 5×24 with plastic lenses and an internal aperture stop, making it slightly more effective than just sighting down the tube.
About The Mount
The 127EQ’s mount is an actually somewhat decent EQ-1 mount, made almost entirely of metal and actually capable of holding the 5” OTA with only slight wobbliness. Unfortunately, it could be the best mount in the world and it would 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? Do ya?
I spent a few days doing everything possible to get a 127EQ I was given to work. I’ve owned dozens of telescopes. I’ve serviced hundreds. I know what I’m doing, and after all of my effort I was still presented with images worse than any real telescope I’ve ever looked through.
So, to summarize this review of Celestron Powerseeker 127EQ, there are better options than the 127EQ in its price range. There are better options than the 127EQ well below its price range. Please don’t, 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 dump.