Telescope Toy Story

You know the story. Andy’s sixth birthday brings him Buzz Lightyear, displacing Sheriff Woody. The other toys share Woody's grief until (as always) they confront and surmount the challenges. And they lived happily ever after. 

Right now, 14:23 hours 05-July-2026, we are in the trope’s “save the cat” pages of the script. 

[Earlier versions of this narrative were posted to Cloudy Nights discussion “New 70mm Maksutov from Spectrum Optical Instruments” started by Jim Riffle on December 3, 2022 in the Cats & Casses Forum. My comments there are #321, #323, and #335.] 

Back left: white: Explore Scientific 102-mm doublet refractor
Front left Astronomers Without Borders 130-mm Newtonian 
At right: Spectrum Optics Tour Star Pro Maksutov-Cassegrain.

The Newt Rebellion

June 27: For the past couple of weeks, I have been getting out more with my “tabletop Dobsonian” from Astronomers Without Borders. It is a Newtonian reflector 5 inches (130 mm) in diameter and it comes without a tripod but it does have a Vixen mount for universal compatibility and I put it on a ES First Light Pan-Tilt Mount.

The AWB dob needed collimation (aligning the primary and secondary mirrors) but it was not too far off and it pretty much stayed that way night after night. The time before last, I tweaked it again and made it dead-on to within a gnat's whisker. The next afternoon (June 28), the Spectrum Optics Maksutov Cassegrain telescope arrived from Astronomics and I set it up. 

Left: AWB 130 on ES First Light Mount.
Right: Meade StarPro 70 mm.
They got along fine.  

Set-up was easy. I intended to take out the AWB reflector to compare the views. When I looked in the collimation eyepiece, the view was horrific: the entire primary mirror was two-thirds off center, ten times more wrong than it ever had been. I adjusted the three primary screws at the back. That was ineffective. I adjusted the three secondary hex bolts up front. The changes were not the ones I sought. I loosened the main mount of the secondary mirror mount. It only got worse. I took the AWB 5-inch reflector and two cases of small tools into the house. 

Unexplained Sightings 

June 29. After the unusual failure of the 130-mm Newtonian from Astronomers Without Borders, I took out the Explore Scientific 102-mm doublet refractor. To other stargazers, I identify this as “my grab-and-go.” On its mount, with accessories, the package is 20 lbs (9 kg) and it always works. Tonight, the red-dot LED finder scope would not come on. 

Click. Click-click...pause...wait... do it again... 

Easy enough, I got another battery. Nothing. Click. Click-click...pause...wait... do it again… Batteries fresh from the pack seldom fail, therefore the LED on the finder must be dead. (Later, I checked the battery and it still had high potential at 3 volts.)

Next, I chose a Celestron 51630 Star Pointer from inventory. With dabs of white-out, I match-marked the On-Off and Up-Down and went out and ran errands. A couple of hours later, I went to the telescope to check the alignment on the red dot finder and the On-Off switch was broken: it clicked Off but rotated fully through On without clicking On. and there was no red dot.

Explore Scientific 102-mm refractor.
Note at right on the eyepiece mount 
is a Stellarvue Correcting Prism with fine focus.
(I think that taking this off the ES-102 and putting it
on the Mak-70 was a point of contention among the scopes.)

Portland Cement on a Horta

July 3. I filled out a request slip and gave my tool check to the guy at the crib for an AstroTech Multiple Reticle finder the same as I use on my AstroTech 115 mm  Extremely-low Dispersion Triplet refractor. Then I found a new base to fit both the ES 102 telescope and the new finder. I settled on the closest match and superglued the plastic bases to each other. 

Homepage ad from Spectrum Optics
At $159 it was very competitive in its class.
Astronomics had these for $100. 
So, I bought five for four friends and myself. 

Right now, the mount for the finder is narrower than the draw of the clamp attaching it to the stand. So, now, I am looking for shims. Passing up scrap aluminum and plastic, I tried folding and rolling paper, then turned to plastic soda straws before cutting to lengths a cardboard stylus for cellphones. To hold the shims, I used SuperGlue gel. It is not a permanent repair but it will work until I get new finders from Explore Scientific. Now, I can use the grab-n-go for all of the deep space objects in my southern skies from 10:00 PM to 2:00 AM and continue to test the Maksutov against the near competitors in my shed.

[Sunday. July 11. 23:30. Like the Official Dog in Eric Frank Russell's "Alamagoosa," the patch failed under gravititic stress. The telescope is back in the shed under wraps "until I get new finders from Explore Scientific."]

[Tuesday. July 14. 16:03. I bought three replacements from Explore Scientific. (I have another 102-mm refractor like this one but longer.) The trees that they are on do not fit the slot in the telescope. I got out the shoebox with new and used finder bases and found a close match. After sighting and aligning on a nearby chimney, when I go out again, I will have to remember that "center" is down and to the left of the red dot.]

 

The salient problem remains: Why all the failures? 

Notes: 

Astronomers Without Borders branded their entry-level hobbyist instrument in the name of John Dobson, a problematic Vedanta Hinduist who sought to unify religion and science by building large telescopes from scrap parts and taking them to the streets of San Francisco to show people the skies they did not know.  

A Sidewalk Astronomer, documentary film by Jeff Jacobs: 

https://www.youtube.com/watch?v= bVbX19kabNc

Tribute by the Planetary Society

https://www.planetary.org/profiles/john-dobson

Wikipedia of course

https://en.wikipedia.org/wiki/John_Dobson_(amateur_astronomer)

Dmitry Dmitrievich Maksutov was serving in the USSR military when he invented this design. Like the Cassegrain and Schmidt, the Maksutov design benefits from a folded optical path, allowing twice the focal length or half the tube size. Moreover, the "negative miniscus" of the secondary optics corrects for spherical aberration. However, the Maksutov design allows aberrations when the diameters of the component mirrors exceed 100 mm (4 inches). So, these tend to be small and lightweight, which is perfect for hobbyists. Moreover, the telescope is sealed: there is nothing for you to adjust. 

PREVIOUSLY ON NECESSARY FACTS

A Good 70-mm Refractor 

National Geographic 70-mm Refractor Field Test 

A Good Entry-Level Telescope 

New Telescope Familiar Sights 

Setting Up and Using Three Small Telescopes

21-March-2026 General Observing - 14:00 - With a weather forecast of clear and warm (70F) tonight, I took out my usual telescope, an Explore Scientific 102mm doublet refractor. I also unpacked my 5-inch Celestron tabletop Dobsonian reflector from Astronomers Without Borders. I even took out the Sears 6307B/4 60-mm refractor that Laurel found on the street in 2023. My goal was to use this one with my iPhone 15 on a NexYZ adapter to take pictures, at least of the crescent Moon. 

The extra gear was too much weight for the 1962 hardware. I did get to see the Moon at 35X with the 20mm Huygens and then 46X with the 15 mm Kellner oculars. I had other telescopes set up and waiting for use, so I stopped fussing with the camera. With clear nights ahead and no work in the morning, this could be a project. All of us old guys on the astronomy boards started with telescopes like this. (See Mr. Olcott’s Skies: An Old Book and a Youthful Obsession by Thomas Watson, on Cloudy Nights as desertstars.)

I am going to make this joke again: With a 60mm doublet refractor and Huygens eyepieces, I can see what the universe looked like in 1750. 

The AWB Newtonian needed collimation after over a year in storage. The process was the easiest it has ever been. I went in to the archives here under \Astronomy\OtherInstrumentManuals\Collimation and found 63 files. I chose Astro Babys Guide to Collimation. After the introductory materials,  they say on Page 3: 

Rule 1 – Before starting collimation don’t assume that anything is out of kilter and check each element before adjusting anything. About 90% of collimation errors are down solely to the primary mirror so don’t jump in and start meddling with the secondary unless you are sure that there is a problem. Each stage of this guide will show you how to check the various elements – only if they are out

of alignment will you need to make adjustments.[The red is in the original.] 

They continue with a reminder to get all the tools you need before you begin and allow enough time to work this through slowly and do not over-tighten anything. Then on Page 4, they jump right in adjusting things that don’t need attention. “Collimation Step 1 – The Spider Vanes and Secondary Mirror Holder.” So, I put that aside and went to my bookshelf. Philip S. Harrington’s Star Ware: The Amateur Astronomer’s Guide to Choosing, Buying, and Using Telescopes and Accessories.  A quick look at his directions agreed with Astro Baby’s preface. Sighting through the collimating eyepiece and rotating the three adjustment screws and their set-screws, it was easy to put the donut in the center view. 

21:23 - with Meade 5000 14mm 82-degree. Messier 41. 

21:55 Messier 42 - Trapezium sharp. Then, Messier 41, Sigma Orionis, and. Mintaka. 

(There was a lot of playing with the Red Dot Finder on the AWB. I finally got it aligned into agreement with the telescope.)

Put the reflector on a different tripod and put it back in the storage shed with the Sears.

Continued with the ES-102. 

22:29 - Jupiter. wavery; in and out of focus; lots of atmosphere. 

Spent ten minutes lying on the picnic table bench looking up at Leo because it was not distinct at first. The view did not get any better with exposure.

22:32 - a last look at Sigma Orionis; another look around: the Big Dipper was behind the oak tree. I put everything away.

Overall, although I made no personal discoveries it was a good night out following an afternoon of setting up two telescopes that I had not used in over a year. 

PREVIOUSLY ON NECESSARY FACTS

Observation Log (December 28, 2023) 

Virgin Galactic VX01 VX03 

The Structure of Scientific Revolutions 

Tunguska, Chelyabinsk, Berlin, and New York  

The Universe of 1962

Laurel found a Sears 6307B 60mm F=700 (f/11.67) from 1962 on the street. I brought it home and I bought 0.965 inch eyepieces for it from The Surplus Shed. 

 

On 2 August, I viewed the gibbous Moon to align the finder scope (with crosshairs) and to check the eyepieces. I bought a standard set: 6 mm, 12.5 mm, and 20 mm. The telescope came with those, as do many such even today, though more often, just two, 10mm and 20mm. These were Huygens eyepieces, a two-lens design from the 17^th century. I also bought a 16 mm “wide view” Kellner, a three-lens 19^th century improvement. I was cautioned by a friend online at Cloudy Nights that these replacements being plastic were not as good as the original equipment. That was easy to accept. The original 6mm eyepiece was with the scope and it is made of metal and (apparently) glass. However, it had a problem with corrosion or something that would not come off with Zeiss lens cleaner. 

The next night, I split the double star beta Scorpii (Graffias) with the Kellner at 43X. The view was not wide enough to take in all of Messier 7 the Ptolemy Cluster but I was satisfied. I could not locate Messier 80 or M22 which was disappointing. I believe that the optics would do it, but fussing and fiddling with the over-engineered and under-built mount was frustrating. 

I will nod to the engineering, however. Unlike a modern telescope, you focus this well enough with the eyepiece draw tube and then finely tune the focus with the controls. Similarly, the altiude and azimuth are found roughly close and then, with those bolts tight, you adjust the alt-az settings with knobs on the fine tuning engagement. With more practice, I could learn to do it.

 

The next morning I viewed Jupiter’s bands, its polar band – a pleasant surprise; why we call long focal length refractors “planet killers” – and noted that three of its moons were visible. 

I then turned to Messier 42, the Orion Nebula, found it easily, and (another surprise) the Trapezium was clear and bright and sharp.

 

Happy with the experience, I put the telescope away very carefully. My current instruments are much better, of course, but if I had to live with only this, I could. And just to note, I do have two Celestron Huygens oculars with standard 1-¼ inch barrels. Putting them into a 70mm refractor, I kidded online at CN that I was viewing the universe as it looked in 1650. It looked OK.  Better instrumentation is better, of course, but double stars, open clusters, a bright globular were all truly visible and enjoyable.

 

 

PREVIOUSLY ON NECESSARY FACTS

The Andromeda Galaxy 

Xi Scorpii

An Online Class in Astrophysics

Viewing Mars 

 

THE ANDROMEDA GALAXY REVISITED

With a hospital a mile away and schools all around, my northern sky here is worse than it was in Austin. Except for finding Messier 81 three times in ten or more attempts, nothing near the Big Dipper is available even with the aid of a computerized “go to” mount. However, being out at 5:00 AM, I found Cassiopeia readily and was pretty sure that I could make out the smudge of Messier 31 off the sharper vertex of the W. And I did. 

This morning, between 5:18 and 5:38, I viewed the Andromeda Galaxy with an Explore Scientific 102-mm f/6.47 achromatic doublet refractor because that one was closest to the door. The oculars were a 14-mm Meade 4000 series 82-degree, a Nagler 7-mm Ploessl, both of those with and without a basic GSO 2X Barlow. So, variously 47X and 94X with more or less eye relief.

 

If I did not know in advance what I was looking at, I would have classified this as a globular cluster. There was some shape to the smear, longer than round, with some central sparkle. It seemed to have a halo but that could have been atmospheric effect. The centrality of the bright core came out with averted vision, looking away left, right, up, and down, changing between left and right eyes. Several times, I moved a bright star to the center and refocused more tightly. Overall, it was more like Messier 4 which is also spread out and not like Messier 22 which is a tighter circle of light.

Addendum: 02 September 2022. Orion 70mm refractor with Meade 25 mm Modified Achromat and with Celestron 32 mm Super Ploessel Wide Angle. Nominally "clear" skies but with much residual moisture from current rainy season. It took some doing from 0340 to 0420. I found M31 naked eye and with Bushnell 12x42 binocular and then needed several attempts to locate it with the telescope. As above but not as large, it looked like a globular cluster, brighter in the circular center with indistinct fading left and right.

 

PREVIOUSLY ON NECESSARY FACTS

 

The Andromeda Galaxy

Viewing Mars 

Recent Astronomical Observing 

The Map that Changed the World 

Forbidden Planet 

When Worlds Collide 

A Good Entry-Level Telescope

Keep the telescope. Throw away the mount and tripod. Keep the eyepieces as curios for historical reference. The average beginner telescope costs about $159 whether from Orion, Celestron, or Explore Scientific. For that money, 70% of the value is in the optical tube assembly (OTA: the telescope itself) another 20% is in the useless junk that goes with it and then 10% is lost to packaging, instructions, and perhaps extras such as star charts. So, what does it take to build a good entry-level telescope?

 

Start with the Mount.

Just as the scabbard called “Avalon” was more powerful than “Excalibur” (the blade it sheathed), the positioning mechanism (“mount”) is more important than the telescope. 

 

The best entry-level mount and tripod that I have is the Explore Scientific First Light Twilight Altitude-Azimuth with slow-motion controls. It costs $349.99. I use it for my ES 102-mm f/6.47 refract0r, my Astronomers Without Borders 130-mm Newtonian, and all of my 70-mm refractors. 

 

I found that the Orion VersaGo E-Series Altitude-Azimuth mount—rated for 11 lbs (5 kg)—is sufficient for the 70-mm refractors. It retails for $99.95 and is currently marked down from Orion at $89.99, which indicates to me that this will be discontinued. I bought four of them, one for each of the 70-mm scopes that I will sell and another for the one that I will keep. It also can carry the AWB 130mm Newtonian which weighs only 5 lbs (2.3 kg).

Orion VersaGo E-Series Mount is $100.

 It is not perfect. The gearing does have sloppy “backlash.” You have to turn the slow-motion controls several twists for them to engage in any direction. Even so, it is better than every other competitor. 

 

Previously reviewed here, 70-mm refractors from 
Bresser, Meade/Orion, and Celestron.

The original Meade alt-az mount did not work at all in left-right azimuth, no matter what the tensioning. The Bresser German Equatorial mount likewise failed to provide even crude adjustment. The Celestron movie camera pan-tilt mount was cheap plastic incapable of any smooth motion. So, for the money, the Orion VersaGo does let you have good control of the viewing field, left-right and up-down.

All Tubes are Created Equal.

Just as we are different individuals who are equal under law, so, too, are these telescopes somewhat different but essentially equivalent. The optics are a given. It is for this reason that Sky & Telescope's  Gary Seronik is a fan of cheap binoculars: the expense is in the gears, not the glass. (See Binocular Highlights reviewed here.)

 

The Celestron 70-mm AstroMaster has a longer focal length: 900 mm or a ratio of f/13. So, it offers more magnification with a given “eyepiece” (ocular). It is important not to be seduced by useless magnification advertised in bright colors on the box of a department store telescope. In her guide, Celestial Sampler, Sue French (a Sky & Telescope columnist), typically views with her 4-inch telescope at 47X. 

 

However 900/12.4 > 72 and 900/32 > 28 and a 2X Barlow will double the larger to modest but sufficient 144X. Those numbers are not importantly different from the magnifications of the competitors. 

The Orion and Bresser are both f/10 telescopes, focal lengths of 700 mm. And the oculars will render images at 56X and 21X (doubled to 113 and a convenient 43X). 

 

Moreover, with a refractor (though not with a Newtonian) you can place a 2X Barlow ahead of the diagonal rather than after it and in so doing enjoy a 3X magnification. Personally, I experienced that observing technique and it can be inspiring if not overly more informative. It does offer mid-range options for 65X or 84X. 

It is a simple fact that different objects viewed under different sky conditions will look somewhat better or worse for marginally more or less magnification. So, you want incremental arrangements.

 

Some Oculars are More Equal than Others.

The Bresser 70-mm Callisto comes with 25 mm and 9.7 mm Plössl oculars (“eyepieces”). These are standard, modern designs, two matched pairs of plano-concave lenses. For want of an umlaut, the name often appears as just Plossl or more correctly Ploessl. Even expensive, complex, computer-driven entry-level telescopes arrive with older ocular designs, called “Modified Achromatic” or “Ramsden Achromatic” or “Modified Kellner”, all of which are three-lens arrangements. The Celestron AstroMaster comes with two Kellner oculars, 20mm and 10mm. The Meade StarPro comes with three Kellner eyepieces, 26 mm, 9 mm, and 6.3 mm, and a 2X Barlow lens.
 

·       2020-December-6 Focus on Georg Simon Ploessl 

 

I found better “Super Plössl” eyepieces of focal lengths 32mm (GSO brand) and 12.4mm (Meade 4000 series) to add to the instrument packages. The advantages are better construction: metal barrels, not plastic, blackened inner tubes to eliminate stray reflections, better glass in the lenses and closer specifications in production. 

Better oculars sold by Astronomics (left) 
and Agena Astro Products (right).

Also, the longer focal lengths deliver better “eye relief” a measure of how near or far your own eye must be from the lens to get the best view. With cheaper, smaller lenses you must be uncomfortably close to the eyepiece, with a smaller cone of light, and it is like viewing Grand Canyon through a soda straw. With the wider view of better eye relief, you come close to that very rewarding “walk in space” experience when stargazing.

 

What Can You See With That?

It is an easy generality that most backyard stargazers make the famous “double double” of Epsilon Lyrae the gold standard for performance. I achieved that view with each of these. It depends on the “seeing” the quality of the sky, more than on the aperture of the objective or the magnification of the ocular. Given those parameters, each of these 70-mm refractors at their greatest magnifications will split all four stars into two binaries.

 

Of course, there is more to backyard stargazing than that. Double stars Albireo in Cygnus, Algieba in Leo, Zuben el Genubi in Libra, Graffias in Scorpius, open clusters like Messier 44 the Beehive, and globular clusters such as  Messier 13 in Hercules, as well as Mars, Jupiter, and Saturn and more are all available. 

 

I have been at this for a while, ever since being given my first (adult) telescope for my 65^th birthday in 2014, a Celestron 130-mm Newtonian reflector on a German Equatorial Mount. I  used this blog to gather my thoughts, observations, theories, and opinions.

 

·       2019-December-14 Defending the Hobby-Killer Telescope 

·       2019-December-14 In Support of the Entry-Level Telescope 

·       2021-November-7 70-mm Shootout 

·       2022-May-22 Product Review: Bresser EQ3 and f/10 Refractor 

 

You can find other informed opinions. On the popular discussion boards (Cloudy Nights, Stargazers Lounge, Sky Searchers) every introduction in the Beginner’s Forum that asks “What Should I Buy?” receives an easy 12 to 20 opinions, sometimes running into lengthy arguments between aficionados. The highly regarded Nightwatch: A Practical Guide to Viewing the Universe  by Terence Dickinson (revised fourth edition, 2019) recommends a 6-inch Dobsonian as the ideal beginner scope. It offers a large aperture, is easy to collimate–align the mirrors; a requirement of frequent maintenance for any Newtonian–and with a base of 25 lbs (11 kg) and a tube of 15 lbs is easy to carry in two pieces.

The true costs of a decent beginner telescope
(Don't forget shipping and taxes.)

 

That all being true, a smaller refractor comes to ambient temperature quicker than the tube of a Dobsonian. Until you reach temperature, you will be viewing through a column of shimmering air in the tube. Also, a larger aperture returns a worse view when the atmosphere itself is turbulent whereas a smaller diameter objective transmits a lower ratio of noise-to-signal.

A refractor requires no collimation. (At least, it is very infrequent and should be done by returning it to the seller for proper work). Also, the 1200 mm tube is a stretch if you want to collimate by looking into the alignment tool while adjusting the back screws. It is not clear to me what you do with the tube when it is not mounted. In other words, the refractors can be set on their Vixen bars without affecting the optics. Can you lay a Dobsonian on its side? You do not want to stand it on its mirror. If you stand it on the opening, is it stable? And once set up, how easy is it to move that 1200 mm (four feet long) 50 lbs tube on its box mount? 

 

Currently $460 from Astronomics, 
and several others.

I agree that the 6-inch Dobsonian is a great telescope, all in all. No telescope is perfect. I selected the 70-mm refractor for portability and range of targets based on frequent and easy backyard viewing. 

 

PREVIOUSLY ON NECESSARY FACTS

The Origins of Technical Writing 

Readability is the Only Metric 

Visualizing Complex Data 

An Objective Philosophy of Science