[HN Gopher] The tiniest yet real telescope I've built
___________________________________________________________________
The tiniest yet real telescope I've built
Author : chantepierre
Score : 242 points
Date : 2025-12-12 07:35 UTC (15 hours ago)
(HTM) web link (lucassifoni.info)
(TXT) w3m dump (lucassifoni.info)
| Nition wrote:
| I always love the moment in blog posts like this, where the
| writer with their esoteric knowledge of the project will say
| something like "I almost considered reflaboring the exahenge, but
| of course it would be a ridiculous prospect for a project of this
| type". And then always, inevitably, there is the followup edit;
| "I reflabored the exahenge."
|
| Too rarely in life are things made better than practical
| consideration would dictate, just because of dedication to the
| craft.
| chantepierre wrote:
| Your comment brings me back to my first mirror making
| adventure, I was absolutely overwhelmed by the jargon and
| acronyms used by the mirror making community... a few years
| later I internalized it and use it as if it was common
| knowledge. I should put little explanations or details in my
| posts.
| awesome_dude wrote:
| A friend of mine once told me - learning a new field is all
| about learning the language of that field
| eru wrote:
| That's a big part of it, but far from everything.
| awesome_dude wrote:
| I'm not really sure - I deliberately stopped there
| because the concepts related to that field are a part of
| the language learnings.
| jiggawatts wrote:
| What they hear:
|
| _" Exorcise the lattice hoard to siphon the new
| incarnation."_
|
| What we said:
|
| _" Purge the web cache to download the new version."_
| lukan wrote:
| That metaphor would here be pretty accurate, though.
| BobaFloutist wrote:
| I think that's probably not an accident.
| macintux wrote:
| A friend of mine asked me why we have such precise
| terminology in IT; I asked her why English has so many
| different words for "chair".
| Nition wrote:
| There was enough there for me to get the basic idea, which is
| fine I think. Can't really expect every niche post to have
| all the details necessary for a general audience and it's fun
| to get a glimpse into these worlds anyway.
|
| Thanks for sharing the post!
| aa-jv wrote:
| I just love the fluent use of terms, and the whole ontology of
| the subject itself just seems so appealing to me. For a moment,
| I felt like others feel when listening to me and my colleagues
| discuss kernel build issues or other software challenges -
| befuddled, bemused, enchanted.
|
| I guess, if/when I retire to that remote mountain hideaway, I
| might just get into this hobby. The idea of grinding my own
| mirrors to look at dew on the spiderwebs of the neighborhood is
| just so appealing.
| dekhn wrote:
| History is made by people who reflabor the exahenge.
|
| I build microscopes instead of telescopes (as a hobby). I can't
| tell you how many times I've taken a mostly working system and
| stripped it down to make some important change that affects
| most of the design to get only a tiny incremental improvement.
| Sometimes that improvement makes all the difference (for
| example, being smart when 3d printing a piece that carries
| something heavy so it doesn't deflect) and sometimes it's just
| an itch I need to scratch. Eventually, I learned to make two: a
| microscope that gets built and used, and then a microscope that
| is a prototype. Then I'm not tempted to take the daily driver
| and pull the engine.
| taneq wrote:
| Well yes, but are you wiggling the giblet or are you flensing
| the grobbulus? Because the latter requires specialised
| equipment and a flensing trampoline, whereas the former
| requires a 1mm Allen key and possibly a hard whack on a
| nearby surface while nobody's looking.
| dekhn wrote:
| Flensing trampolines are out of my budget, so it's just
| giblet wiggling for me.
| cadr wrote:
| Ooh! Tell us about microscope making as a hobby!
| dekhn wrote:
| Uh, OK. So a few decades ago a scientist I respect built
| his own scientific tool from parts
| (https://www.nature.com/articles/35073680) and I was really
| blown away by that idea, especially because most scientific
| tools are very expensive and have lots of proprietary
| components. I asked around at the time (~2001) and there
| wasn't a lot of knowledge on how to control stepper motors,
| assemble rigid frames, etc.
|
| Although my day job is running compute infra, I have a
| background in biophysics and I figured I could probably do
| something similar to Joe Derisi, but lacked the knowledge,
| time, and money to do this either in the lab, or at home.
| So the project was mostly on the backburner. I got lucky
| and joined a team at Google a decade ago that did Maker
| stuff. At some point we set up a CNC machine to automate
| some wood cutting projects and I realized that the machine
| could be adapted to be a microscope that can scan large
| areas (much larger than the field of view of the
| objective). I took a Shapeoko and replaced the cutting tool
| with a microscope head (using cheap objectives, cheap lens
| tube, and cheap camera) and demonstrated it and got some
| good images and lots of technical feedback.
|
| As I now had more time, money, and knowledge (thanks,
| Google!) I thought about what I could do to make scientific
| grade microscopes using 3d printer parts, 3d printing and
| inexpensive components. There are a lot of challenges, and
| so I've spent the past decade slowly designing and building
| my scope, and using it to do "interesting" things.
|
| At the current point, what I have is: an aluminum frame
| structure using inexpensive extrusion, some 3d printed
| junction pieces, some JLCPCB-machined aluminum parts for
| the 2D XY stage, inexpensive off-the-shelf lenses and
| industrial vision camera, along with a few more adapter
| pieces, and an LED illuminator. It's about $1000 material,
| plus far more time in terms of assembly and learning
| process.
|
| What I can do: the scope easily handles scanning large
| fields of view (50mm x 50mm) at 10X magnification and
| assembles the scans into coherent fullsize images (often
| 100,000x100,000 pixels). It can also integrate a computer
| vision model trained to identify animacules (specifically
| tardigrades) and center the sample, allowing for tracking
| as the tardigrade moves about in a large petri dish. This
| is of interest to tardigrade scientists who want to build
| models of tardigrade behavior and turn them into model
| organisms.
|
| Right now I'm working on a sub-sub-sub-project which is to
| replace the LED illuminator with a new design that is
| capable of extremely bright pulses for extremely short
| durations, which allows me to acquire scans much faster. I
| am revelling in low-level electronic design and learning
| the tricks of trade, much of which is "5 minutes of
| soldering can save $10,000".
|
| I had hoped to make this project into my fulltime job, but
| the reality is that there is not much demand for stuff like
| this, and if it does become your job, you typically focus
| on getting your leadership to give you money to buy an
| already existing scope designed by experts and using that
| to make important discoveries (I work in pharma, which does
| not care about tardigrades).
|
| Eventually- I hope- I will retire and move on to the more
| challenging nanoscale projects- it turns out that while you
| can build microscopes that are accurate to microns with
| off-the-shelf hardware is fairly straightforward, getting
| to nanoscale involves understanding a lot of what was
| learned between the 1950s and now about ultra-high-
| precision, which is much more subtle and expensive.
|
| Here's a sample video of tardigrade tracking- you can see
| the scope moving the stage to keep the "snout" centered.
| https://www.youtube.com/watch?v=LYaMFDjC1DQ And another,
| this is an empty tardigrade shell filled with eggs that are
| about to hatch, https://www.youtube.com/watch?v=snUQTOCHito
| with the first baby exiting the old shell at around 10
| minutes.
| cadr wrote:
| Having it automatically follow tardigrades is so cool! It
| sounds like great fun. Did you make the ML model for
| tracking them?
|
| I've wanted to make this the Openflexure Microscope
| (https://openflexure.org/projects/microscope/) but it is
| behind the backlog of all sorts of other things.
| dekhn wrote:
| Yes, I took an existing vision model that could run at
| realtime on my laptop, and fine-tuned it with a few
| hundred manually labelled images of tardigrades.
|
| I don't like the openflexure design at all. I mean...
| obviously it works for a lot of people, but I just don't
| want a flexure based stage. I like real 2-axis stages
| based on rolling bearings, basically cloning the X and Y
| parts of this:
| https://www.asiimaging.com/products/stages/xy-inverted-
| stage...
|
| UC2 is another cool project: https://openuc2.com/ but I
| found their approach constraining.
|
| Frankly I think you could just buy an inexpensive 3D
| printer that had an open firmware, and replace the
| extruder with an objective, a tube, and a camera, and
| you'd have something up and running cheaper for less
| time.
| chantepierre wrote:
| Hello, author here ! Other interesting builds or projects going
| on in the french amateur telescope maker community :
| - Sunscan, by the STAROS team : a fully integrated open-source
| solar imaging kit : https://www.sunscan.net/fr -
| Eric Royer's binocular 24" dobson :
| http://www.astrosurf.com/topic/124758-bino600/ - The
| Slim400 by Laurent Bourrasseau :
| https://www.cloudynights.com/forums/topic/920950-the-slim400/
| - Astrowl, an electronically enhanced astronomy kit :
| http://www.astrosurf.com/topic/151807-projet-astrowl-de-visuel-
| assist%C3%A9/ - The smallest, an open-source 6"
| portable dobson : http://www.astrosurf.com/topic/176898-un-
| dobson-150-f5-facile-%C3%A0-imprimer-et-assez-compact/
| - A dedicated astrophotography power supply :
| https://github.com/Antiath/Open-Power-Box-XXL
|
| Of course there are many others but those are the one on the top
| of my head now
| 9Mfhf34U wrote:
| Do you have an RSS feed just for the astronomy posts on your
| blog?
| chantepierre wrote:
| No, but that should be quite straightforward to add with
| Astro, I will check that. Edit : it seems
| that I now do have one :
| https://lucassifoni.info/blog/tag/astronomy/rss.xml
|
| I am not an RSS user myself, I tested it with an online
| reader and it should be working.
| 9Mfhf34U wrote:
| Cool, thank you very much.
|
| I just tried it, the links don't seem to be working. I get
| sent to https://lucassifoni.info/miniscope-tiny-
| telescope.mdx for example
| fransje26 wrote:
| Thank you for the links and the write-up!
|
| I'll share them with a friend who loves astronomy and who loves
| to organize star-gazing events that he livens up with his
| Unistellar telescope.
| waerhert wrote:
| Very cool, thanks for sharing! Any ideas of adding 2 gimbal
| motors to this for GOTO? MS6010v3 or something lighter would
| seem like a good fit.
| hrldcpr wrote:
| clickable links in case it's helpful for anyone:
|
| - Sunscan, by the STAROS team : a fully integrated open-source
| solar imaging kit : https://www.sunscan.net/fr
|
| - Eric Royer's binocular 24" dobson :
| http://www.astrosurf.com/topic/124758-bino600/
|
| - The Slim400 by Laurent Bourrasseau :
| https://www.cloudynights.com/forums/topic/920950-the-slim400...
|
| - Astrowl, an electronically enhanced astronomy kit :
| http://www.astrosurf.com/topic/151807-projet-astrowl-de-visu...
|
| - The smallest, an open-source 6" portable dobson :
| http://www.astrosurf.com/topic/176898-un-dobson-150-f5-facil...
|
| - A dedicated astrophotography power supply :
| https://github.com/Antiath/Open-Power-Box-XXL
| aidenn0 wrote:
| You wrote up "of course I refigured it" as if refiguring
| mirrors is something any reader would know how to do. I (and I
| suspect most of HN) does not; have you (or others) written on
| this topic?
| chantepierre wrote:
| Sure ! Here are a few links :
|
| https://stellafane.org/stellafane-main/tm/index.html
|
| How to make a telescope, by Jean Texerau, which was the
| absolute bible of this field : https://rexresearch1.com/Astro
| nomyTelescopesLibrary/HowMakeT...
|
| Here is a talk (in french, but maybe the auto-subtitling
| would work?) I recorded that overviews the whole process
| (2h30 though, and lacks info on the Bath) :
| https://www.youtube.com/watch?v=Wt7lBLS0ueg
|
| Here is Gordon Waite's youtube channel which actually shows a
| lot of the moves :
| https://www.youtube.com/@GordonWaite/videos
|
| Best resource on the Bath (french, but should translate well)
| : https://gap47.astrosurf.com/index.php/technique/optique-
| inst...
| aidenn0 wrote:
| Merci!
| clusterhacks wrote:
| Wow, thanks for the link to Texerau. I had no idea a pdf
| was floating around and have wanted this book for some
| time. You video looks interesting, especially the part
| around Ronchi and Focault testing. I have 'Understanding
| Focault' but have to admit that reading it doesn't give me
| confidence.
|
| One question I always think about is how much time and
| effort a "one-time" mirror maker should plan on making to
| exceed the quality of a generic 8" or 10" F/5-F/7 available
| from the Chinese mirror makers.
|
| Zambuto seems to imply that whatever magic happens for his
| mirrors might be in very long, machine driven polishing to
| smooth out the final surface imperfections that cause
| scatter. With his retirement and with few mirror makers in
| the US, it seems like options for buying "high end" mirrors
| in the 6"- 10" size are very limited. I have been debating
| an 8" F/7 and would love to just purchase a relatively high
| quality mirror, but most of the mirror makers seem more
| taken with significantly larger mirrors.
| groos wrote:
| I'm sure he didn't explain it because almost nobody knows
| what it is (or even how to interpret the interferograms he
| showed) and learning to figure optics takes years and entire
| books are written on the subject.
| isolli wrote:
| Very nice! But you won't beat this ;)
|
| > Optical Engineer Rik ter Horst shows us how he makes very small
| telescopes (at home) which are intended for use in micro-
| satellites.
|
| https://www.youtube.com/watch?v=HxwhCmO90UQ
| danhau wrote:
| Came here to link this, but you beat me to it :)
| jcims wrote:
| You both beat me. :D
| chantepierre wrote:
| Rik's monolithic Cassegrains are the perfect example of the
| blend of amateur and high-end professionnal work in
| astronomical optics, thanks for linking it ! His amateur work
| is incredible, like this 16" CDK :
| https://www.cloudynights.com/forums/topic/558284-a-400-mm-f1...
| jiggawatts wrote:
| Dayyum, those shots are incredible! I've seen worse pictures
| from professional telescopes.
| tejtm wrote:
| This coming year ... if the crik don't rise (as it does with
| some regularity). Some of you may be able to take a picture of
| yourself with one of Ril ter Horst lenses as it will be
| launched in a 2U cubesat named OreSat1 by Oregon's Portland
| State University undergrads.
|
| https://www.oresat.org/home
|
| pictures would be captured by hand held groundstations
|
| https://www.oresat.org/technologies/ground-stations
| amelius wrote:
| Nice video, except it could use some, you know, actual images
| made by the lens they talk about.
| VLM wrote:
| Its the usual Youtube thing where there's multiple videos.
| The one linked is the bibliography popular science utterly
| non-technical spin. There's a three part technical series, a
| fun two hours viewing, and the end of the third technical
| video goes has some performance shots. It performs really
| well for a tiny little thing, like per gram or per cubic
| centimeter the performance is excellent. Its a cool
| technology and when I saw it I immediately wondered if it
| would be possible to make a microscope the same way out of
| single solid cylinder of glass. I don't think so; but it
| would be cool. It would also make an interesting, although
| probably very expensive, binocular technology.
| ggm wrote:
| When did buying a mirror on Ali overtake grinding your own? I
| guess when Ali became Edmund scientific ie mirror grinding hasn't
| been a thing since I was in shorts (the 70s)
| chantepierre wrote:
| We buy pre-dug mirrors on Ali to refigure them, or dig and
| figure our own all the time. See Ali as a supplier of
| prepolished blanks :) . The l/6 I mentioned in the post are l/6
| spheres, so they also need figuring.
| mapt wrote:
| Mirror grinding is still a thing. Just not a thing that young
| people generally do. Distribution got easier and real estate
| got more scarce. Those of us who have garages, have filled them
| up.
|
| In my understanding it's gotten considerably easier over the
| years with better availability of diamond and CBN abrasives,
| and with more electronic control of the grinding hardware.
| Slumping glass and bonding a thin sheet to ceramic foam reduced
| the costs and weight a great deal as well. Mastering these
| techniques make it easy to start a small business rather than
| to do a one-off in your garage, though.
|
| As a sidenote: The Celestron RASA astrographs are so effective
| and so inexpensive of a wide-field instrument that it's a lot
| harder to justify the DIY activity that existed in the 2000's.
| chantepierre wrote:
| There is quite a vibrant community of young people grinding
| mirrors, it just has displaced to Discord. The "Observational
| astronomy" discord server has a lot of late-teenagers and
| young adults grinding. Our french Astro-FR server has people
| in their thirties grinding. But as you pointed out, garages
| are sparse and people seem to take shortcuts : finding bad
| pre-polished mirrors as blanks, slumping glass sheets to
| shape and continuing with fine grinding...
| buescher wrote:
| If you just want a serviceable telescope, you haven't been able
| to really save any money by grinding a mirror for decades,
| unless you're a madman like Dobson who scrounged blanks in the
| form of things like porthole windows. But that's not why people
| do it. I haven't built a non-trivial telescope but it is not
| too unusual for amateur telescope makers to figure mirrors to
| precision that you can't easily buy, i.e. not for amateur
| prices. Where he talks about Ali mirrors being l/6 or better?
| That's really good for randomly buying something unspecified
| cheap on Ali. l/6 is lambda/6 which means the surface error of
| the mirror is less than 1/6 a wavelength of light. Utility
| optics are typically l/4. Really fine stuff is l/10 or l/20.
| chantepierre wrote:
| I will correct the article, I've found great l/6 or better
| spheres on Ali, but have yet to get a well corrected mirror.
| But starting from a l/6 sphere instead of a flat glass blank
| saves so much time !
|
| For this specific mirror, I was a bit disappointed, because
| it was specifcally advertised as parabolic, which made this
| project suitable, because coating costs trump all other costs
| for very small builds. Well it was 1.7x too much parabolic,
| and now I have to pay a coating :)
| bluGill wrote:
| The only reason to grind a small mirror is because you want a
| very large mirror and need to practice first. This has long
| been the case, but the definition of large has gotten larger
| over time. Of course there is also the in between states where
| you buy a cheap workable mirror, and then make it higher
| quality. Unless you have a lot of land high on a mountain there
| is rarely any point in mirrors that you have to completely
| grind yourself - the telescope wouldn't be portable and the
| nearby light and atmosphere pollution means large sizes don't
| gain enough. (if you do live in such a place your telescope
| could be massive if you have the years to dedicate - can I come
| by and look through it one night after you build it?)
| chantepierre wrote:
| Small mirrors with a very low F-ratio are also something that
| you need to grind yourself. I have a 6" f/2.8 telescope and a
| 8" f/3.5 hyperbolic + ross telescope, and both aren't
| commercially available while being small mirrors !
|
| Progress on my 16" f/3.2 is currently stalled though.. a
| multi-year project indeed.
| 2b3a51 wrote:
| Roughly similar in size to the ones Newton made for the Royal
| Society as demonstration instruments.
|
| https://en.wikipedia.org/wiki/Newton%27s_reflector
|
| Very nice and I might look for one of these mirror kits.
| LtdJorge wrote:
| Very cool blog, not just post
| chantepierre wrote:
| Thanks, it's heartwarming. It's my current longest living
| attempt at a blog
| seanrrr wrote:
| Very cool project! I always wanted a telescope as a kid but kind
| of forgot about that desire as an adult. Didn't know you could
| build your own like this.
| chantepierre wrote:
| If you want to commit to a build, this one is thought to be
| user-friendly and a great first instrument :
| https://www.printables.com/model/1325533-smallest-telescope-...
| seanrrr wrote:
| Thank you! Will check it out!
| clusterhacks wrote:
| Watch your local craigslist or facebook marketplace. With a
| little patience, you will probably find a good 8" or 10"
| dobsonian at a great price. I picked up a lovely 8" dob for
| less than $200. Most of the generic 8" F/6 dobsonians seem
| pretty decent.
|
| Or check your local library. It may have a smaller Starblast
| table-top dobsonian you can check out - I did that when
| traveling once.
|
| Whatever you do, do NOT buy a small cheap refractor on some
| flimsy mount. They are mostly awful.
| bluGill wrote:
| There are a lot of DIY telescopes out there. I suggest you
| spend several days reading about what others have done (and
| why). Start with an easy build to prove you can - people who
| get something small done are much more likely to finish a
| larger telescope, so start small as a practice run.
| ramblin_ray wrote:
| Nice!! I printed a very similar (but larger) telescope back in
| 2018 with similar results... I didn't research my mirrors well
| and ended up with bad ones. Plus, it wasn't very stable at that
| size. I'd imagine a smaller version would be much more stable...
| Thanks for sharing!!
|
| https://yesteryearforever.xyz/ABSDBS
| chantepierre wrote:
| This is the first time I've seen a build of the ABSDBS in the
| wild, thanks for sharing ! Sadly an 8" f/4 mirror has a very
| narrow range of acceptable optical quality :/. It's too bad you
| ended up with a bad one. Maybe refiguring it would be a great
| followup project though
| jimnotgym wrote:
| What I got from this is:
|
| If you want a working telescope for $small, buy a second hand
| one.
|
| If you want to mess around with mirrors for hours on end then
| build one!
| chantepierre wrote:
| Absolutely, second hand is the most direct path to getting a
| telescope.
| tgtweak wrote:
| So what are these tiny portable ones? I always assumed they were
| digitally augmented or virtual even - is there a minimum size for
| it to be a "real" telescope?
| chantepierre wrote:
| This one is a bit of a joke with my telescope making friends,
| but ticks all the boxes of what I consider a real telescope.
| You can actually buy 76mm entry-level telescopes, but they
| often have an unstable mount and bad optics. Starting at 150mm,
| you already have a lot of punch under dark skies. Visual use,
| live digitally enhanced, or astrophotography are 3 different
| hobbies.
| err4nt wrote:
| So cool! Thanks for sharing. It reminds me of one of those very
| old cameras with the bellows or accordion. I wish I could look
| through it myself to see what you see with it!
| chantepierre wrote:
| This article gives great impressions of what you can see with
| your eyes through various sizes of telescopes :
| https://www.deepskywatch.com/Articles/what-can-i-see-through...
| groos wrote:
| Excellent. I might have a go at this myself. Was there a
| particular AliExpress seller that you got the mirror from?
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