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Review of a discarded 2003 National Geographic Society 50mm Refractor
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Review of a discarded 2003 National Geographic Society 50mm Refractor
MSRP (2023 Model): $27.99 from eBay stores with accessories
One of the more interesting things for an amateur astronomer to encounter in the wild is an unexpected telescope. Whether through the exchange of money in a garage sale, thrift store, through gift or trade, or as in the case of my experience with this telescope – finding it after it was discarded by a prior owner, discovery is what we live for.
Section 1: Discovery and Identification
For comparison, the “Classic” variant of this telescope does have differences vs. the “Modern Era” version of this telescope. While the basic quality, design, and likely value remains unchanged, there are differences which are cosmetic in nature and not felt to make a substantial difference between the classic and modern era variants:
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Classic 2003 National Geo. Telescope (as advertised, not as found) |
Modern Era 2023 National Geo. Telescope |
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Dew shield: ~60mm |
Dew shield: ~100mm |
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Adhesive focuser knob covers (missing on the telescope in this review) |
Painted plastic focuser knob covers |
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Found with a 4mm “High Power” eyepiece and a diagonal mirror. |
Accompanied by two eyepieces (4mm & 20mm), a diagonal mirror, a 2x Barlow lens, instruction manual, planisphere, and an aluminum, tabletop tripod that can be classified as Alt-Az |
With no labels, box, or manual to reference, I set about using the claimed 18x to 180x magnification from box images to determine a focal length through back-calculation using the formula FL/EP (Focal Length/Eye Piece) = Magnification. Somewhat surprisingly given the claims on the box, the math worked out the same in both cases. With a telescope like this, it is judicious to trust, but verify, rather than take any claims at face value. This “Classic” National Geo. Telescope (CNGT) appears to be a 50mm F/7.2 (360mm FL) device.
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“Low Magnification” 18x = FL/EPlow FL = 18*EPlow FL = 18*20 à 360mm |
“High Magnification” 180x = Barlow * FL/EPhigh FL = (180/Barlow) * EPhigh FL = 90*4 à 360 |
Section 2: Preparation for Use
An interesting statement is found on the box:
“People use telescopes for all sorts of different things – you can use one to explore the craters of the moon and the rings of Saturn. Scientists use huge contraptions in space, like the Hubble telescope, to view objects normally undetectable by telescopes on Earth. Even wildlife biologists use telescopes – for observing wildlife, not space objects!”
- Rear of CNGT box marketing claim
After reading that, I found myself eager to try it out. As someone who identifies as one of the people who use telescopes referred to on the box, I decided to use this telescope for all sorts of different things, just like the box said was possible. Since the original tripod, Barlow lens, and low power eyepiece were not included in the discovery of this telescope, I made the following substitutions:
· There was no way to mount the telescope, so in place of a standard rings/dovetail configuration, a mitered piece of wood was hot glued to the underside of the CNGT optical tube, meeting Losmandy dovetail specs.
· In place of the tabletop Alt-Az aluminum tripod, a Skywatcher EQ6R-Pro mount was used to hold the mitered wood mounting plate. Counterweights proved to be too much mass for the scope to balance, so a counterweight was created from three oranges and a counterweight extension bar.
· An Apple iPhone13 was used to attempt capture through the 4mm eyepiece with varying results.
· For reference images, a ZWO 30F4 guide scope with ASI290 was used by hot-gluing a spare SVBONY guide scope dovetail onto the dew shield. Images were captured by ASI software. No image stacking or post-processing was done, reference images are raw, single frame captures.
· I wanted to substitute out the eyepiece, but this scope uses 0.965” hardware throughout the visual train and I actually do not have any of that size to substitute.
In its found state, the telescope was basically unusable, so I disassembled, cleaned, and put it back together, hoping for the best. A photo of a tree before and after illustrates the difference that the cleaning made. Despite the improvement, hope was initially low.
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Before |
After |
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Section 3: Apparatus as Used
With the accessories (including the battery, guide cam, mount, laptop PC for capturing, and oranges) added to test the scope, the system MSRP had increased significantly over the $27.99. The intent was to rule out any effect that substandard gear might have on the system in order to achieve the cleanest results possible. Photos were taken of the setup during daytime and nighttime sessions, the equipment was the same, but results were completely different by session.
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Daytime observation |
Nighttime observation |
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Section 4: Results
Upon completion of cleaning and reassembly, I set about attempting to make visibility tests in daylight first, to familiarize myself with a telescope that was initially an intuitive, yet very uncooperative device.
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CNGT (90x) |
ZWO 30F4 Guide scope |
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Daytime Target 1: Trees
Recognizable as trees through the eyepiece. |
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Daytime Target 2: Clouds
Strangely, blue sky looked exactly the same as clouds through the eyepiece. |
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With my daytime imaging done, I made a plan to image at night and waited for the sun to set, hoping that the cloud cover would break up and the nighttime conditions would be the environment where the CNGT could prove itself, or at least let it do whatever it could do to the best of its abilities given the environment that it would be operating in (indicated by the blue star).
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CNGT (90x) |
ZWO 30F4 Guide scope |
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Nighttime Target 1: Moon.
Craters, mare, a clear limb, and terminator were all visible. The iPhone-EP captures do not do justice to the image that was visible in the eyepiece. Being a 0.965 EP tube, there was no option to move the ASI290 for imaging. |
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Nighttime Target 2: Jupiter
2-3 of the main moons were visible at most times, and the iPhone-EP captures are not representative of what was actually visible. This was, by far, the biggest surprise of the night. |
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I was very surprised, given how the daytime tests had performed so poorly. Nighttime viewing was a totally different experience and appeared to be from a totally different hardware setup.
There were three distinct experiences in this telescope.
1) Looking through this particular sample of this line of telescopes during the daytime, as found, was the closest thing I have seen to a cataract simulator. I have new sympathy for people that have sight disorders after using it. Daylight viewing does not justify picking it up when coming across it for free, but it is impossible to attribute at least some of the flaws to the condition it was in.
2) Once cleaned, daylight viewing was vastly improved, but still very bad.
3) At night, the scope really surprised me. It was able to reach focus on both the moon and Jupiter, despite a terrible 4mm EP and a very loose, coarse focuser.
Section 5: Conclusion/Summary
I would like to revisit the box’s marketing statement:
In thinking about these claims and the wording specifically, it should be noted that they are made about telescopes in general terms, and not the telescope actually contained in the box, or the one I found, assuming it came in the same or a similar box. So it is, that this telescope must be judged on its own merits, both against the claims made by National Geographic’s marketing team and in general.
· Can it be used to see the craters of the moon? Probably not when found in the condition mine started out in. After cleaning, the telescope clearly resolved craters on the moon.
· Can it be used to see the rings of Saturn? I have my doubts, but it was able to clearly see Jupiter and it’s at least three of the major moons (Jupiter’s location in Dec 2023 was very helpful). Sky conditions were such that Saturn was not an option. If a person had significantly better skies than were available for this review, it would be an interesting test.
· Can you observe wildlife? Trees are living things, so, yes, it was able to see a tree. The strength of this scope is not daylight observing and the equatorial mount chosen for this review is a suboptimal way to observe wildlife. I really can’t comprehend how this telescope was so bad in the daytime and such a pleasant surprise at night.
To buy or not to buy.
I would like to have found a complete setup in the wild to test further. The scope, as tested for this review, would be one that I would be willing to give to a person that I did not like, but even then, I like astronomy too much to spite someone away from the hobby. For free, this telescope was worth picking up and providing a day’s worth of entertainment, but I would rather spend $27.99 on other equipment.
Conclusion: Do not buy, whether in “Classic” or “Modern Era” trim.
- John O'Hara, deepwoods1, bob irvin and 10 others like this
30 Comments
It's too bad you didn't have a .965-1.25" diagonal to try out with it. Once you throw out all the cheap accessories and strap it to an expensive mount and camera, dirt-cheap refractors can be surprisingly fun. I use a $60 70/400mm for polar alignment with SharpCap, but a lot of nights I enjoy leaving it on a lot longer and imaging through it.
I'm guessing your daytime view was spoiled by all the blue. My little refractor can't focus blue at all - I can capture the horsehead with it, but Altinak is enormous. So all the blue of the sky was probably spread out defocused across the field, killing any contrast for the parts of the image it actually could focus well. Wildlife observation may work better if there's no blue sky in the background, although with a mirror in the train instead of an erecting prism it would be annoying.
The focal ratio of 7.2 gives the scope a chromatic aberration value of 3.66 between the Sidwick limit (2.88) and the (stricter) Conrady limit (5) for minimal CA.
Some inexpensive small achromats, like the (misleadingy named) "Galileoscope" kit, have 50 mm objectives with an f/10 ratio that gives near apochromatic performance with CA=5.06. Given the small size this scope would have done well to copy this pattern.
I have a Svbony 502 ‘kids’ refractor with the same basic specs. That is, an air spaced, 50mm x 360mm f7.2, The difference is that the native visual back is 1.25 inch, so not .965.
This refractor is still available from Svbony’s ebay store for $30 with free shipping. Ordered mine for less 3 months ago with additional discounts.
The objective is pretty good right up to 90x with a 4mm EP. The most comfortable high power however is 60x with a 6mm Expanse 68 degree EP.
It comes with a 45 degree correct image diagonal which I replaced with a 90 degree RACI diagonal.
This is actually a useable featherweight 50mm telescope, as long as you put some work into accessorizing it with better visual end diagonal and eyepieces.
Of course the table top tripod and its connection to the telescope were discarded and a vixen compatible homemade cradle were substituted. The included finder and its studs were also removed and discarded.
With a 25mm plossl it is its own finderscope at about 14x at 3+ degrees true field size.
I also shortened the R&P focusing tube to 6 inches from the as supplied 9 inches to prevent vignetting of the objective. This means you can roll the focusing tube all the way out the back since it does now not have a stop, but there is no reason to ever do that.
I've bought and tested a ton of different f/7 50mm lenses off Aliexpress and all showed these crazy amounts of scatter. Think Zane Landers reviewed one of these travel 50mm scopes and found it was internally aperture masked to 20 or 25mm, I'm guessing to improve the objective. There's a lot you could do with a (pair of) f/7 50mm but none of the mass produced objectives seem to measure up. Nice try, thanks for sharing your results.
(Edit: One very funny thing you could do with this scope is replace the objective with one from Edmund Optics. They are $180 but you'd secretly have a tiny refractor that can do 116x on planets/Moon.)
They should be ashamed of themselves for putting their name on such trash. I know it's hard to sell magazines these days, but putting out that kind of thing really smacks of desperation.
Wonderful review.
I particularly would like to see how this would work with a 31 Nagler; the gold standard low power ep for telescope reviews. Some would say that this is impossible but I don't think so. You already have a glue gun so I think a funnel could be modified to allow the ep and "adapter" to slide in the focuser. Of course you will have to replace the oranges with Clementines to compensate for the weight but the EQ6-R will probably work OK. (Astrophotographers on CN would recommend a stronger mount for the 6 pound lead because as some say..."50% capacity is the rule of thumb but I am always happier with 12.5%.) Anyway, at 12X, were it not for the somewhat constricting effect of the repurposed Rubbermaid funnel, you would have an impressive 7.06 degree field of view. With this you could see all of metropolitan Oil City Pennsylvania in the field of view. Or at least all you wanted to see of Oil City Pennsylvania. (Don't get on me. You can see many fine oil industry historical sites in and around Oil City. I am not making fun of it. Really. Not.)
Well great review. If you want I could send you a 2X .965 Barlow if you want to build on your fine research. Do you think ScottinNC would DPAC test it?
I think that that would be fun to do, but I don’t believe I have a step down adapter that would allow my gear to work on a 0.965” focuser, if that’s indeed what this scope has.
Readers might be interested in a review of the very similar Celestron Travel Scope 50.
http://scopeviews.co...avelscope50.htm
Sometime after reading that review I came across one of these scopes for sale on eBay, stripped of the case and all accessories, for about $12. I couldn't resist.
When the scope arrived, I made two of the changes described in the article: I knocked the ridiculous baffle out of the drawtube, and I spray painted the drawtube's interior flat black. I didn't saw off the end of the drawtube, though. Thus modified, the scope works at about f/10.
Since I didn't have any 0.965-inch accessories, I ordered a used 15x microscope eyepiece (about 17mm focal length, for a magnification of about 22x with the scope) and a correct-image 45° diagonal. The seller for the diagonal reneged, but after I complained to eBay I received two of the diagonals.
The quality of the image cast by the objective was great, as I expected. It was the diagonals that surprised me. I've owned a number of 1.25-inch 45° correct-image diagonals, and every one of them has noticeably degraded the image. One of the tiny 0.965 diagonals was just as bad, but the other, to my delight and astonishment, was sharp.
The modified scope, with its microscope eyepiece and cheapo diagonal, was so good that I bought a solar filter for it and took it to Albuquerque last November to view the annular eclipse. The view was terrific. Here's what the scope looked like.
I'll take the scope with me to Texas next month for the total eclipse, but for that I'll need to use 90° diagonal because the eclipsed sun will too high in the sky for the 45° diagonal to be comfortable.
This scope has turned out to be a real treat. The Svbony 502, described by John R. a few posts above, ought to be even better, with its 1.25-inch focuser--and well worth the trouble of modifying the mounting hardware
They have been the bottom of the pile for years.
I doubt their public relations people know one end of a telescope from the other end. Tee shirts, telescopes, coffee mugs, and other assorted promotional flotsam, it is all the same to them, 'How much unit cost if we buy 5K pieces.' That bottom line is the only consideration.
the entire VB is 0.965, but when i posted my adventure fixing up a 60's tasco https://www.cloudyni...40-for-a-tasco/, there were recommendations of 0.965 VBs, but i opted for a simple 0.965-1.25 adapter for it. i did this review back in Dec i think, but the mod was backlogged and the article was released after the tasco was retrofitted. I no longer have the "classic" nat geo scope to use all the 0.965 parts that came with the tasco. life threw the two scopes at me in the wrong order...
many thanks. i was grounded from the glue gun because apparently it is for crafts and not real science. my wife is running low on glue sticks. the EQ6-R was tolerant of the load as it was built, but i felt like i had some room to go heavier. what i needed to do, since i went to the effort of mounting that 30F4 on it was some guiding so i could do long iphone exposures through the eyepieces and stack them in powerpoint or MS Paint. Maybe in time there will be another telescope of this... caliber for me to tinker with.
I found this both really interesting from a technical side yet, I was dying laughing while reading this!
The oranges & hot glue...lol, creative but it worked 
Thank you for this! Really interesting to read about what a kids telescope looked like compared to what we know today. More importantly, it's been a crappy day and reading this just cheered me up
It never ceases to make me giggle when amateur astronomers break out equipment in an attempt to make a $30 telescope resolve something. "The 31mm Nagler, AP diagonal, and the steadier platform offered by the Losmandy G11 made up for some of the shortcomings of the plastic objective and clothes hanger tripod of the original kit. Hopefully, when children find this telescope under the tree, they will also find the $5,000 straight cash absolutely required to make this anything close to capable of resolving the outline of something as small as a mountain. Conditionally Recommended for budding young astronomers who sometimes struggle to carry out their 130mm triplets."
The first telescope I got for my 7th birthday in the 1980s was an earlier version of this Nat Geo telescope in Tasco red. .965 eyepieces, skinny tripod, useless, dim optics, it was at least a start.
gfstallin, $5k, thats hilarious, on my planet, I just need a sheet of black sandpaper to line the tube, drawtube, barrels on the eyepiece and diagonal for good contrast. Total cost $5. These poor scopes are only suitable for ATMers to improve, not little kids, but there will be the little engineer to prove me wrong though. hehe. Admittedly, fast scopes will require a focuser change to get rid of vignetting, and baffles may need to be moved, changed or removed, and lets not forget the doublet will likely need to be respaced to get the SA corrected. Perfect scope for the kid engineer to learn on.
Recently I picked up a Vivitar refractor for a quarter, views appeared color corrected, but hazy, turned out, the manufacturer put the achromat in backwards with the flint facing the sky !
Then there are the diagonals to watch out for, I had one that had a second surface mirror that was astigmatic. It will be getting an old porro prism from a broken 7x35 bino as a replacement. I may be
but you'll be surprised what performance can be had from some of these "junk" scopes, though with the 50mm and smaller class scopes, some of them aren't even achromatic. Celestron, I'm looking at you
, with your telescope, microscope, bino set (model 22010). Give the kids some expensive narrowband filters for free to enjoy sharp images out of their nonachromatic refractor!!!! Or just charge $5 more for an achromat lens 
. Oh and how about adding a 25mm eyepiece too! Now im 
. Roast done haha.
I got too curious about "those telescopes with the National Geographic brand name on them" a couple of months ago when I saw one with an included solar filter and smartphone adapter. When i got it set up per the instructions I actually got a decent look at some sunspots. The main problem was that it was so shaky that 1) I would NEVER recommend that anyone let a child use it for fear he'd go blind, and 2) it wobbled so badly that I could only get fast glances in the eyepiece as it wiggled past. No way to hold it steady. I was somewhat interested in the smart phone adapter since I didn't have one, but it's about the same as holding the phone in your hand but with a slight bit of rubbery texture that improved the grip a little. Now I know.
Your review of a terrible telescope was hilarious, I will share one of my best CL purchases.
I answered a CL add for a "small telescope and planetarium... $14". I thought this would be a pile. The refractor was an EDU 50mm, 1.25 with 3 eps-4,15 and 25 and a 90* diagonal, and a CD. It had a broken LED starfinder. The plastic alt-azimuth mount was awful, and turning left at Orion resulted in the main screw backing out instantly. Right turns only. (The Uncle Milty planetarium is fun though!)
I cleaned the scope and took it out one night to view Jupiter. It was a surprisingly good view! I saw one dust band, and a a hint of the other. Then I noticed an orange spritz behind Jupiter, like a folded paper fan. It was Saturn! I actually got good views of Jupiter through this telescope. Viewing the Moon was a shocker, I had well defined views.
I put the scope away, waiting for someone to give it to. Much later, I answered a CL add for an Apertura AD8. The owner tells me it's new, assembled, but never used, it has become Decor.
We settled on a price and location, I took the EDU 50 with me. As he walked away from the completed deal, I said oh wait I have something for you. I have not heard from him since, though I had invited him out to view from his once proudly purchased scope. I hope he at least got a couple good views for free through the EDU 50. I can almost say he got the better deal.
sometimes it's not about the destination, but the journey and a cheapie telescope joy ride was a nice change of pace.
i had a lot of fun coming up with ways to run this telescope through a controlled test for free and it was such a relief not to have some narrow window of opportunity or equipment constraint that limited me from executing the plan of a specific night-image-timeline. in the end, i would do it again, i just hope the next time i find a telescope, it's at least got a 1.25" VB because that would open up so much more of my test bench and apparatus selection.
Glad I could be a comedian for ya! Regarding your CL scope, I'm guessing you were following directions in a certain book when disaster hit. I am going to guess there were intentions on conducting Sirius observations with the little scope.
I love that you were rigourously testing a toy telescope. I enjoy cheap telescopes, they offer a challenge of making it good. Maybe we'll discover a cheap gem and start a craze.
I've been reading, learning from, and enjoying these forums for years, but never joined until now. I did so because I wanted to comment on your photograph. It is overflowing with love. Love for family. Love for discovery. Love for astronomy. Thank you so much for sharing it.
There is a thread ‘Unusually inexpensive refractors’ that had 1500+ replies in a years time.
There is evidence that sometimes the view from ‘the cheap seats’ ain’t bad.
My personal experience with one particular refractor, a Spectrum AstroLite 60, has been delightful. It is a simple, air spaced 60mm x 500mm f8.3 achromat that can still be had for coffee money (almost) or $51.84 to your doorstep.
This 1.5 lb. wonder is often the first out the door at my house, and that although I also own an AT80ED and AT70ED. It is, I believe, that “cheap gem” you speak of and I can recommend with out too many reservations.
I understand your disappointment in this review. It is important to be able to share your opinions and experiences, but each of us has our own preferences and assessments. It's good that you showed such respect for astronomy despite your disappointments.
I had very low expectations, but I was pleasantly impressed by the lunar performance of the scope. The review was written in a way that I intended to intermix humor by the rigor of the testing, not really expressing disappointment. It was a free scope and otherwise free time on my hands. I thought it was a fun time in a sometimes unforgiving hobby.
No need to spend that much. For $51.84 a Spectrum AstroLite 60 is delivered to your door step. Even though the included tripod is so so, the 60mm x 500mm f8.3 is a lot better than it has any right to be for that price. Not tiny at 22 inches OAL with it's RACI diagonal but is only 1.5lbs. and is effortless to deploy. For planets I use a 6mm Orion Expanse for 83x and screw in the optical block of a shorty barlow for 1.5x and 125x total.
An amusing review! I've tried to fix one of those National Geographic 50mm's too. It's an education. Those cheap scopes tend to be horrible, but they figure some kid will get it and destroy it in a couple of hours. So no big deal.
>What they can do with these is stop them way down with a baffle behind the objective with a much smaller opening so if it says f9 on the box it might actually be f18. That sharpens things up a bit and improves the color.<
(But) The best part is when they finally get some decent optics and it all takes off into a new dimension. These crappy starting scopes are a stage to pass through so you know the good stuff when the glorious images hit your eye and brain.