chantepierre

Hi ! It is quite easy, with 2 tilt screws at the secondary cage, and the primary cell floats on three heavy duty springs. I can shake it and nothing moves, this is my first criteria. I collimate with a cheshire tool but always finish on a star at medium power (since this telescope realistically does not reach high power, since it would need 2mm eyepieces which are the opposite of wide field views). I use it with Explore Scientific 17mm 92 degree, and a 13mm APM XWA 100 degree eyepieces, and do star collimation with a 6.7mm eyepiece.

So most of the use is at 25x, to frame huge objects like NGC7000 or the largest extensions of M31

To me, there are two models that stand out from the crowd :

- The Hadley, a 4"1/2 f/9 dobsonian telescope, which is a smaller aperture but easy to build and to find optics for, and very mature : https://www.printables.com/model/224383-astronomical-telesco...

- The "open smallest telescope" from a friend, which I show here, a foldable 6inch f5 dobsonian : https://lucassifoni.info/blog/2025-best-6-inch-f5-150-750-po... and can be found on Printables : https://www.printables.com/model/1325533-ost-open-smallest-t...

Both are very cool projects, the smallest shows more for deep sky but costs a bit more in optics, and the Hadley has a very mature community.

Hi, thank you !

I am using DFTFringe ( https://github.com/githubdoe/DFTFringe ) with a Bath interferometer (specifically this model which is super handy : https://www.printables.com/model/986094-multi-bath-interfero... ) and this 3-axis table which is bulky but simple to build ( https://www.printables.com/model/860316-xyz-platform-for-bat... ).

I am also trying to automate the XYZ table, capture and analysis like WavefrontPro does, I have a POC going on that bases itself on a CLI-only build of DFTFringe + outside orchestration with Elixir. My goal would be to control everything with a gamepad and automate the whole test session. Here is a video : ( https://www.youtube.com/watch?v=ii2eGb7vbk4 ). But I need to throw the code away and rewrite it.

After this year's Paris marathon, I ran the same per-minute graphs, and they match perfectly the "overall study" graphs with more than 9 million finishes in the article. I also added graphing by age category and gender. I don't want to deduce too much but I think it showed that young men are the most "competitive" (what I mean by that is targeting a specific time) since there are the clearest "goal time" peaks in the graphs.

There is no rest. There is just (properly done) a continuous output from start to finish, or a very slight increase of output (negative splitting), but effort to maintain it feels exponential. In terms of feeling, it’s a 32km « dynamic run » where you should feel good, then the hardest 10k you can pull off just after that. If paced properly there should not be a « wall » but at all levels you pass people walking who disintegrated around 30km. Even people with sub-elite/elite bibs sometimes explode.

A half is more intense but way easier, you’re just sub threshold but for a time short enough that you cannot really not make it.

Yeah you're right, I hear it more like "this is a week long hike, not a sprint" as if a marathon included rest. In any length of racing there's no tomorrow. But I'm doing tongue-in-cheek pedanticness here and will stop that right now !

It makes me smile when runners use "X is a marathon, not a sprint" to hint at an effort that accumulates over time and an optimal use of energy.

I do it too because it's a common expression, and a marathon is of course longer than a sprint, but both have in common that properly raced, they are absolutely brutal efforts that leave you without a single additional drop at the end. The effort length and instantaneous power output changes, of course. Maybe "it's a marathon build, not the race" would be more precise at the loss of nearly all its expressive power (but with a lot more pedanticism points) :-p .

Nice project !

"German mode" is an interesting idea !

I routinely use "load bearing" in conversations and writing, both seriously and ironically (like a "load bearing just" or "load bearing paint").. maybe I should stop.

I felt that but find it worked way better by invoking it with `claude --effort max` only

The hydrogel textures (not maurten but naak, but close enough), for me, allow while racing to swallow a full 40g gel in half a second without feeling the sugary taste a lot, which is nice. Compared to thick syrup-like gels, it’s a way better experience in a marathon.

But I only buy for actual races, rest of the time, I do my own 1:0.8 mix with a bit of thickener, in soft flasks. Much more cost effective.

Converting an app that started per-client deploy, single-tenant, cloud-ignorant and mono-node to multi-tenant, multi-node, cloud storage and a cluster of a few nodes.

On one hand, I regret not having thought it could find a market and I now have to do this and plan a migration.

On the other, I saved a lot of time going to customers instead of building the boring side first... So I don't know what to think of it.

I find that most of the development work is now "ops" instead of user-facing features (either addition, removal, or polish) and am a bit perplex at this.

Here is a 6in f/5 travel truss dob kit by my friend :

https://www.printables.com/model/1325533-smallest-telescope-...

Wallace, my 6” f/2.8 :

https://www.printables.com/model/997327-wallace-6-f28-telesc...

And my tiny but mighty 3” f/4 : https://www.printables.com/model/1475113-76300-pocket-dobson

Wallace is built, but Gromit, a 16.5” F/3, is under progress. Working on the mirror and CAD :)

Re : running relaxed, it is said that the real marathon is the training you put in, and the race itself should feel like a celebration. I am not anywhere near elite level but felt that for a lot of races. The hardships of the training enables a state of deep calm, joy and feeling like you are flying the morning of the actual race. Nights before races are often very bad, like a last storm before everything clears and your mind is finally empty when you get into the corral. Then, with a clear mind, you proceed to run with joy despite being physically tired by the training and sleepless night.

Hi, I could send you the link but as outlined in the post, this specific mirror was very out of tolerance..

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/AstronomyTelescopesLibrary/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...

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...

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.

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.

Absolutely, second hand is the most direct path to getting a telescope.

Thanks, it's heartwarming. It's my current longest living attempt at a blog

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

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-...

I will correct the article, I've found great λ/6 or better spheres on Ali, but have yet to get a well corrected mirror. But starting from a λ/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 :)

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...

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.

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...

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.

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.

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