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Celestron AZ 102 refractor telescope review – through the eyes of a beginner
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Celestron AZ 102 refractor telescope review – through the eyes of a beginner
SUMMARY
The Celestron AZ 102 refractor telescope from Costco is a starter telescope that produces solid views of a range of deep sky and solar system objects. It requires some maintenance and benefits from upgraded components.
PRODUCT DESCRIPTION
The Celestron AZ 102 refractor telescope has a 4-inch aperture and fully coated objective lens. It has a 660mm focal length and a focal ratio of f/6.5. It has an erect image, 90 degree, Amici prism star diagonal.
It comes with a 20mm Kellner eyepiece for low magnification (x33) and a 10mm Kellner eyepiece for medium magnification (x66).
It ships with a manual alt azimuth mount on an aluminium tripod.
PERFORMANCE TESTING
I purchased the Celestron ‘AZ 102’ refractor telescope from Costco, Australia, for $350 Australian dollars (US $235) in 2023. I have used it for 18 months, observing a full range of objects from suburban Melbourne, Australia, at latitude 37 South.
The model tested was Celestron item number 22159-DS. From information on the internet, it seems almost identical to the Celestron ‘Omni AZ 102’ available from Costco USA and previously available from Costco Canada, possibly as Celestron item number 22157-DS or 22158-DS (check the box).
It should not be confused with the current ‘Omni XLT 102’ refractor telescope available from Celestron as item 21088 which has a 1000mm focal length and f/9.8 focal ratio, on a German Equatorial mount.
MECHANICAL PERFORMANCE
As my first telescope, I was pleased with the attention to design and construction wFhich made it feel like a proper telescope rather than a toy.
The optical tube assembly felt solid. The long dew shield conveniently blocked stray light from streetlights and neighbouring houses. The lens cap fitted well and had a smaller opening for reducing the aperture to 2 inches for looking at brighter objects. The focuser was simple and smooth to use.
The red dot finder was easy to install, calibrate and use. With no magnification, it suited me as a beginner looking at and navigating around the brighter objects.
The mount and tripod were easy to set up and adjust. The adjustable height allowed for viewing in a comfortable seated position or standing. The angled mount arm allowed viewing from the horizon to almost straight up above. Slewing the telescope using the fine motion control rods was smooth.
The light weight of the overall setup made it easy to carry around when moving it to different locations in my garden to look at different objects throughout the night. The removable accessory tray provided additional stability and was a handy platform for holding the eyepieces and other items.
OPTICAL PERFORMANCE
The telescope generally produced good views of deep sky objects. Open star clusters, bright globular clusters and bright nebulae were clearly visible and pleasing to the eye.
The brightest stars, double stars and inner planets were prominent, but showed some central blurriness, chromatic aberration and diffraction spikes which reduced their appeal. This issue was partially addressed by using the aperture mask to decrease the amount of light entering the telescope.
The outer planets looked beautiful, though slightly blurry. The coloured textures or Mars were discernible. Saturn’s rings were clearly seen. The brighter moons of Jupiter and Saturn were visible. Uranus and Neptune appeared as serene points of light.
The craters and features of the moon looked suitably sharp, detailed and well contrasted when using the aperture mask to reduce the glare.
The correct image orientation produced by the Amici prism diagonal was ideal for me as a beginner. Up was up, down was down, and left and right were as expected. The Amici prism is sometimes described as a cheap component suitable only for terrestrial viewing, however it allowed me to easily and confidently navigate the night sky as a beginner.
DAMPENING TIME
The dampening time for the view to settle after a tap test was around 8 to 10 seconds with the telescope placed on a grass lawn and higher on a concrete surface. As a beginner, I found this acceptable at low and medium magnification, but frustrating at high magnification when I used additional accessories. The maximum comfortably usable magnification I therefore achieved was around x110.
ACCESSORIES
The included smartphone adaptor allowed my standard smartphone to be attached for taking photos. I found it difficult to align the smartphone camera lens with the eyepiece, but when aligned it worked well. The apparatus with phone attached seemed a bit heavy for the telescope and I had to be careful to attach it tightly to the eyepiece and not bump it for fear of it falling off onto the ground.
The included Bluetooth remote paired easily with my phone’s camera and worked well. It was a welcomed accessory as it allowed photos to be taken without touching the camera and introducing vibrations.
UPGRADES
When I upgraded the Amici star diagonal to a higher quality prism diagonal, the views became noticeably sharper and the diffraction spikes and chromatic aberrations became much less of a problem. When I upgraded the Kellner eyepieces to Plossl eyepieces, the views became even sharper again and higher in contrast and detail. With these changes, the resulting views of most objects were delightful.
Star testing showed pleasingly symmetric, concentric diffraction rings when defocussing in each direction. This suggested that the objective lens was of high enough quality to support high quality optical components. Excellent views were later achieved when I tried some premium eyepieces.
MAINTENANCE
After a few nights of enthusiastic use, the fine motion control rods became loose. This was addressed by ensuring the ends of the attachment screws were well centred in their grooves and tightening them at the start of each session. However, with repeated tightening, the head of the supplied hex key became dull and ineffective. After replacing it with a harder steel hex key and tightening the screws extra firmly, the control rods did not become loose again.
After a few months, the altitude gear did not engage at times, making it difficult to track objects vertically using the fine motion control rod. I fixed this by ensuring the optical tube was well balanced on the mount, re-lubricating the altitude gear friction pads and adjusting the gear bolt tension.
After a year, the focuser action became a little coarse. I fixed this by re-lubricating the rack and pinion after accessing its housing with a screwdriver.
A review of internet content suggests I am not the only person who has experienced these issues. There are also a number of fixes posted online.
I do not have enough experience with other telescopes to say whether this level of maintenance is common to similar telescopes at this price point.
CONCLUSIONS
I think the Celestron AZ 102 refractor available at Costco is a starter telescope for a beginner. It is affordable, easy to set up and easy to use. It provides solid views of a range of objects at low and medium power. It can accept upgraded optical components for even better views.
The mount has some potential mechanical issues that can be overcome with maintenance. I would recommend this telescope only for people who are willing to do this themselves or with assistance.
Beginning with this telescope has allowed me to experience and grow into the hobby. With the upgraded components and maintenance issues now sorted, I have a telescope that I really enjoy using.
- CollinofAlabama, Jon Isaacs, scotsman328i and 14 others like this
18 Comments
That's a nice review! Seems like it has many good things going for it, for a starter telescope!
Easy to use mount with slow motion controls is very important as you know!
Clear skies!
Those EPs are typical for Celestron, and are worthless. A 32mm (20x) and a 10mm (66x) Plossl plus a good quality 2x Barlow (41x & 132x) and prism diagonal would maybe cost Celestron $40 more to include and would eliminate the issues that would frustrate a new user.
I agree with your recommendations.
I found this telescope performed well with a 32mm Plossl, giving beautiful wide field views.
Pierre:
A nice review. I have some experience with this scope and I think you covered the important points. I am glad you found the mount adequate. For me, I have higher expectations..
I think reviews of scopes like the Omni 102 are more important than reviews of high end scopes. High end scopes are going to be very good and the differences will be subtle. Scopes like this, people are going to be buying them as first scopes and they really have no idea of what's good and what's bad. A review like yours helps them understand.
I was recently given some astro gear with the idea of that I would give it someone. One of the scopes was the Celestron 102mm F/6.5. I recently gave it to a family friend. The mount was more robust than the stock mount, the eyepieces were Plossls and I had two diagonals, a 1.25 inch mirror and a 45 degree correct image. He is just getting started but I think it's a good fit for him.
Jon
P.S. I think you have the 20mm and 10mm eyepieces reversed.
"It comes with a 10mm Kellner eyepiece for low magnification (x33) and a 20mm Kellner eyepiece for medium magnification (x66)."
I wanted one of these tripods and couldn't pass up one that was missing some parts at a thrift store for $10. The slow motion is driven by worms, but the driven gear is slip-clutched to the axis. This means the scope could always be grabbed and moved without manually unlocking a clutch. This is a beginner-friendly feature, probably also intended to prevent damage when someone inevitably grabs the eyepiece or the tripod is knocked over. It also means the gears can be plastic because if the clutch is adjusted correctly, the gears can never experience much force. But this design might also contribute to the slow damping.
Thanks for your encouraging words, Jon.
I agree that the mount and tripod could be upgraded to address a number of the issues.
Yes, the eyepiece details are incorrectly reversed. It should be "It comes with a 20mm Kellner eyepiece for low magnification (x33) and a 10mm Kellner eyepiece for medium magnification (x66)." I will see if the editor can amened it as a typo.
I was curious to learn if the price had changed, Cosco says $259.99 but are out of stock. The mount looks the same, so Kikrum might be able to find a spare when someone nearby puts it on CL or FBMP. Costco says it weighs 44 pounds My old f/10 4" celestron weighed that.
Good review, you grasped the role of the Omni AZ pretty well - a starter telescope that by itself is a keeper and can grow with you into the hobby. While the included accessories are low quality, they are usable and as you dig deeper into the hobby you'll inevitably buy higher quality accessories anyway. I'd note that many or most of the more expensive refractors aimed at advanced users include almost no accessories. And the other telescopes aimed at beginners aren't including Televue eyepieces either.
I don't contend the Omni AZ is the most financially efficient way to get into the hobby, but it is still efficient because it's a good complement for a bigger telescope like an SCT or Dobsonian when you've graduated from beginner status and it's time to upgrade. I do contend that a refractor is the most user friendly way to start the hobby because they are very user friendly and this one in particular helps you avoid lots of beginner mistakes and hurdles.
Costco.com tells me it is out of stock at my local warehouse, but that they are available for shipping.
BTW- the 44# is shipping weight. Celestron doesn't list this model, but it is very similar to the Starsense Explorer DX 102AZ scope which is 5# OTA & 9.2# mount, so maybe 16 pounds total.
Pierre C,
Welcome to Cloudynights.com, although you are making your own way into amateur astronomy quite well. I agree that a 4" short focal length refractor is a good way, inexpensive way to get into astronomy. I recall using one to find the Flame Tree Nebula, NGC 2024, in the first decade of this century.
FWIW, I purchased a C130SLT tube and had some of the same problems you're having. First, I agree with Jon Isaacs that your mount is not really up to snuff. You'd be better off with the SkyWatcher AZ-5 with large steel legs. But you'll need to get a set of tube rings and dovetail bar for your refractor regardless. Go ahead and buy those now. Even on your too-small mount, they'll make a world of difference reducing your vibration times. Also, if you want to keep this mount and see how far you can go with it, try something like this. This won't make your mount any better, but will further add stability to something you already own. These two additions (rings/dovetal bar and tripod leg support) might even make things a lot more functional for you. These are upgrades that should cost very little. Good luck.
Thank you for taking the time to craft such a well written review - such a benefit to newcomers like myself.
Got the same scope from Costco in November 2022. The most frustrating thing I just couldn’t figure out at first was the altitude slow motion control not working right, or mostly not at all.
Finally dawned on me that the OTA had to be balanced exactly. The too short vixen rail it comes with makes this difficult and I was fortunate to find a set of 100mm tube rings that solves the getting it balanced problem.
I have a better AZ mount now and relegated the Celestron to lighter and shorter refractors.
I think it was fine for the money since Costco finally had it on sale for $160 at end of season that year.
I enjoyed your review. I have an almost identical ‘scope, the Celestron StarSense 102AZ. I bought this telescope because I had advised my sister to buy this model as a starter instrument, and I wanted to have the same ‘scope so that I could tutor her by distant remote communications. I was surprised at the optical quality that this telescope achieves. I did replace the red-dot finder, which I thought was cheap and flimsy, with a Celestron StarPointer Pro, about a $50.00 US investment, and I replaced the included diagonal with a better one, and I used medium-quality eyepieces from my collection instead of the simple ones supplied with the ‘scope. With this arrangement, Jupiter was fairly sharp, its equatorial bands clearly visible at 120x. I think the upper limit for this telescope is around 180x. It’s a fun telescope. I seldom to never use the app-driven PushTo feature of this instrument. It’s fun to “Go Galileo” and use the telescope as a tool to learn my way around the night sky, star-hopping from one object to the next. I’m glad you’re enjoying yours.
What a timely review for me personally, I had been looking around for a used telescope idly for a while, I managed to find this same scope used about two weeks ago for $120 Canadian on Facebook Marketplace. It was missing the red dot finder and the accessory tray but otherwise was in great shape.
I second your finding that the mount seems fairly light duty for its intended purpose, it takes 5-10 seconds for the view to stop shaking if you or the wind touch the setup. Mind you that is with the tripod at full extension and no accessory tray (not sure how much that would sturdy it up really).
Of course after I picked up the telescope it was raining and overcast most days, I really only got to take it out one night so far. I had quite a hard time trying to find my way around, I put most of that down to:
1) No finder scope
2) Likely not finding the "sweet spot" for the cheap 10mm & 20mm kliner eyepieces that came with it.
I have just recently started wearing eyeglasses for small text up close, otherwise my vision is great. I found it quite difficult to get a clear view of the stars, almost like I could not quite bring them into focus. The starts were not sharp, they had what I think are diffraction spikes, were misshapen and had somewhat of a halo. The moon was not out for me to take a look at. I have been waiting for it to come at a more reasonable time of night and try again with the much larger target.
I was looking as some low cost but recommended upgrades that could carry over to a better telescope later. So far the list is along the lines of:
1) A dielectric mirror diagonal (SV188P)
2) a zoom eyepiece (Celestron 8-24mm).
3) a mid to high 30's mm eyepiece
4) a 2 X Barlow (GSO shorty)
I have also been looking at some ways to DIY improve the stability of my included tripod:
1) Make an accessory tray, tight against the upper 1/3 of the inside of the legs
2) Make a secondary tray at the lower 1/3 tight against the legs and add weight atop it
3) Get a longer rail and rebalance the scope on the mount.
My house is in a town about 20 minutes outside the city (100K), my backyard is not that bad for light pollution but there are some street lights on the road. I do have access (20 mins or less) to areas that would be quite dark to use on occasion.
I really appreciate this article and if you or others have some suggestions with respect to what I have, I would welcome them.
The accessory tray is only attached to the center of the spreader and does not contribute to steadiness.
I now have other mounts and the Celestron sits unused.
It definitely needs a longer rail. Fortunately I was able to buy tube rings for mine and that makes it easy to balance the scope. But short of that, then yes, replace the 4 inch rail with an 8 inch, (you will need to drill an additional hole in the tube).
On mine, unless balanced just right the altitude slow motion refused to work, but azimuth always worked.
It’s a fairly lightweight refractor for the aperture.
Your four point list of accessories is about the same as what I obtained, except my zoom is a 7-21 Svbony that seems to do a good job for the low price. I think it is currently about $50 for the zoom.
Since I bought an AT80ED the Omni has mostly sat unused.
A great review of a fun beginner's telescope. I still have one around the house here somewhere, but with so many bigger and better scopes already set up and ready to take outside sitting around in our "parlor," I haven't bothered to search through all of my life-long accumulation of telescope "gear." I have always enjoyed using such relatively cheap scopes. It reminds me that compared to what old Galileo had at his disposal, only after producing them from scratch on his own, the views though the 100 mm Celestron must be like having suddenly getting to use the HST instead of ANY backyard amateur scope.
And wouldn't Galileo have been delighted to learn that in fewer than two centuries after he strained so hard, but never managed actually to discover, that those two "ears" coming off of Saturn were actually a beautiful ring, some clever fellow way up north in England would figure out a way to use two different types of glass to produce objectives that when properly made could reduce all that awful chromatic aberration to the point where one could get a much sharper view with higher resolution! Is there really no end to the progress that science brings us?!
My own case is hardly as dramatic as what a returning Galileo would encounter, but I can vividly remember using my first scope, one of those department store, 60 mm wonders -- which actually didn't perform so horribly badly once I figured out what the primary problem was and replaced the scope's junky Huygens eyepieces with a vastly superior Erfle eyepiece pried out of an old pair of 16x50 binocs to fix it. [The views of the Pleiades then gave me goosebumps!]
Of course I quickly came down with a bad case of "aperture fever" from such a glorious experience. That left me dreaming of stepping up to an actual 3-incher, 80 mm, a scope that catches a whopping 78% more light than the one I already had. [I didn't dare imagine stepping up to a 4-incher, 100 mm refractor since those were still at the time quite rare and very expensive, even when compared to just the 3-inchers. So, you can imagine when how happy I was when I finally had an adult job and could thus afford the luxury of buying myself one of the early Celestron C100s! What a fine scope that was!! I think they were actually produced by Carton in Japan, not Celestron here. Now if I hadn't foolishly sold that telescope for a song somewhere along the line, I would gladly rummage through all my old stored optical gear all weekend long to re-find it!
To me... This review looks more like someone from a sales angle.... and less from a beginner.
I've heard of this tactic before...
.
I was born at night.... but it wasn't LAST NIGHT.
I have a Celestron Astro master 102... It's a quick grab scope that I threw into the Semi when I was driving truck... It's a decent telescope...
Mike
As further information, here are some links to some enduring discussions which provide additional thoughts on this telescope, and address some of the issues raised in the comments.
Celestron 102mm AZ review (2015+)
https://www.cloudyni...02mm-az-review/
Celestron Omni AZ 102 Discussions and Input - Owners Only Please (2019+)
https://www.cloudyni...rs-only-please/