DIY equatorial mount

A DIY Equatorial Mount Using Harmonic Drives

As an amateur astrophotographer will tell you, you just don’t get to capture the really interesting objects without spending a ton of money on some decent pieces of kit. Telescope aside, there really is a surprising amount of complexity, weight, and associated costs with the telescope mount alone, let alone one that is capable of any sort of programmable tracking. [Alan (Jialiang) Zhao] clearly wanted to up their game, and having suffered some of the shortcomings of their Sky-Watcher HEQ-5 pro Equatorial mount decided to go ahead and build an open-source mount, Alkaid, which hopefully works a bit better for them.

In simple terms, the difficulty of photographing an extremely dim, distant object (or one that is larger but diffuse) is that the camera sensor needs to spend a significant amount of time signal-averaging, to gather enough lightSheet of parts freshly water cut from aluminium plate for anything to be seen at all, through the noise. But, this ball of rock we sit on is rotating constantly, so the only solution is to track the object of interest, to compensate. This is referred to as equatorial tracking, and allows the rotation of the Earth to be compensated for during a long exposure.

The design of each of the two axes revolves (sorry!) around the use of a NEMA-17 stepper motor with a 27:1 planetary gearbox, driving into a harmonic reducer gearbox. Harmonic drives (aka strain wave drives) are pretty neat, working on the principle of a fixed, but circularly distorting ring gear that transmits torque from the inside surface to the outside, with almost no backlash. They are expensive parts, but for a super smooth movement, this is what you want. The huge output torque they allow, meant that [Alan] was able to build a mount for a heavy telescope without any counterbalances. Structurally, the whole thing is constructed from 10 mm thick aluminium plates that were cut with a waterjet and subsequently milled to finish. Continue reading “A DIY Equatorial Mount Using Harmonic Drives”

Astrophotography On The Game Boy Camera

The Game Boy Camera was the first digital camera that many of us ever interacted with. At the time it was fairly groundbreaking to take pictures without film, even though the resolution was extremely low by modern standards, and it could only shoot two-bit color. It’s been long enough since its release that it’s starting to become a popular classic with all kinds of hacks and modifications, like this one which adds modern SLR camera lenses which lets it take pictures of the Moon.

The limitations of the camera make for a fairly challenging build. Settings like exposure are automatic on the Game Boy Camera and can’t be changed, and the system only allows the user to change contrast and brightness. But the small sensor size means that astrophotography can be done with a lens that is also much smaller than a photographer would need with a modern DSLR. Once a mount was 3D printed to allow the lenses to be changed and a tripod mount was built, it was time to take some pictures of the moon.

Thanks to the interchangeability of the lenses with this build, the camera can also capture macro images as well. The build went into great detail on how to set all of this up, even going as far as giving tips for how to better 3D print interlocking threads, so it’s well worth a view. And, for other Game Boy Camera builds, take a look at this one which allows the platform to send its pictures over WiFi.

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Watching A Spacewalk In Real Time

If you go to, say, a football game, you probably don’t get to see as much of the game as close as you do when you stay home and watch on TV. But there’s something about being there that counts. That’s probably how [Sebastian Voltmer] feels. While we’ve all seen video of astronauts and cosmonauts spacewalking, [Sebastian] managed to take a snapshot of a pair of spacewalkers from his telescope.

Of course, this wasn’t your ordinary department store Christmas gift telescope. The instrument was a Celestron 11 inch EdgeHD Schmidt-Cassegrain telescope on a very expensive GM2000 HPS mount. An ASI290 planetary camera took the shot. You can see the gear and more about the photos in the video below.

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Hackaday Links: January 16, 2022

As winter well and truly grips the northern hemisphere, it’s time once again to dunk on Tesla for leaving some owners out in the cold — literally. It seems that some Model 3 and Model Y owners are finding their ride’s heat pump isn’t exactly up to the task of, you know, pumping heat. That this seems to be happening mostly in the northeastern US and southern Canada, where a polar vortex is once again dominating the weather and driving temperatures down into the -30 °C (-22 °F) range, perhaps speaks more to the laws of thermodynamics than it does to the engineering of the Tesla climate control system. After all, if there’s not much heat outside the car, it’s hard to pump it inside. But then again, these are expensive machines, some of which have had extensive repairs to address this exact same issue when it cropped up last year. It seems to us that owners have a legitimate gripe with Tesla about this, and they may be getting some help from the Feds, who are taking an interest in the situation from a safety standpoint. After all, no heat likely means fogged up windows, and that’s hardly conducive to a safe trip. But hey, that’s what self-driving is for, right?

Much has been made of the dearth of engineering cameras on the James Webb Space Telescope, and the fact that we’ve been relying on animations to illustrate the dozens of deployments needed to unfurl the observatory and make it ready for its mission. Putting aside the fact that adding extra cameras to the spacecraft makes little sense since the interesting stuff was all happening on the side where the sun doesn’t shine, we did get treated to what was billed as “humanity’s last look at Webb” thanks to an engineering camera on the Ariane 5 rocket. But not so fast — an astrophotographer named Ethan Gone managed to spot the JWST as it transited to L2 the day after launch. Granted, the blip of light isn’t as spectacular as the Ariane shots, and it took a heck of a lot of astrophotography gear to do it, but it’s still thrilling to watch Webb moving gracefully through Orion.

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A Milky Way Photo Twelve Years In The Making

Starting projects is easy. It’s the finishing part that many of us have trouble with. We can hardly imagine completing a project after more than a decade, but seeing the breathtaking results of [J-P Metsavainio]’s gigapixel composite image of our galaxy might just make us reconsider. The photograph, which we highly suggest you go check out in its full glory, has been in progress since 2009, features 1250 total hours of exposure time, and spans across 125 degrees of sky. It is simply spectacular.

Of course, it wasn’t an absolutely continuous effort to make this one image over those twelve years. Part of the reason for the extended time span is many frames of the mosaic were shot, processed, and released as their own individual pieces; each of the many astronomical features impressive in its own right. But, over the years, he’s filled in the gaps between and has been able to release a more and more complete picture of our galactic home.

A project this long, somewhat predictably, eventually outlives the technology used to create it. Up until 2014, [Metsavainio]’s setup included a Meade 12-inch telescope and some modified Canon optics. Since then, he’s used a dedicated equatorial mount, astrocamera, and a Tokina lens (again, modified) with an 11-inch Celestron for longer focal lengths. He processes the frames in Photoshop, accounting for small exposure and color differences and aligning the images based on background stars. He’s had plenty of time to get his process down, though, so the necessary tweaking is relatively minor.

Amateur astronomy is an awesome hobby, and the barrier to entry is lower than it might seem. You can get started on a budget with the ubiquitous Raspberry Pi or with the slightly less practical Game Boy Camera. And if you’re just interested in viewing the cosmos, there are options for building your own telescope as well.

[via PetaPixel]

Explore The Cosmos With This DIY Digital Telescope

Getting a closer look at the Moon isn’t particularly difficult; even an absolute beginner can point a cheap telescope towards our nearest celestial neighbor and get some impressive views. But if you’re looking to explore a bit farther, and especially if you want to photograph what you find out there amongst the black, things can get complicated (and expensive) pretty quick.

While building this 3D printed automated telescope designed [Greg Holloway] isn’t necessarily cheap, especially once you factor in what your time is worth, the final product certainly looks to be considerably streamlined compared to most of what’s available in the commercial space. Rather than having to lug around a separate telescope, tripod, motorized tracker, and camera, you just need this relatively compact all-in-one unit.

It’s taken [Greg] six months to develop his miniature observatory, and it shows. The CAD work is phenomenal, as is the documentation in general. Even if you’re not interested in peering into the heavens, perusing the Instructables page for this project is well worth your time. From his tips on designing for 3D printing to information about selecting the appropriate lens and getting it mated to the Raspberry Pi HQ Camera, there’s a little something for everyone.

Of course if you are looking to build your own motorized “GOTO” telescope, then this is must-read stuff. [Greg] has really done his homework, and the project is a fantastic source of information about motor controllers, wiring, hand controllers, and the open source firmware you need to tie it all together. Many of the ideas he’s outlined here could be applicable to other telescope projects, or really, anything that needs to be accurately pointed to the sky. If you’d like to get started with night sky photography and aren’t picky about what kind of things you capture, we’ve seen a number of projects that simply point a camera towards the stars and wait for something to happen.

[Thanks to Eugene for the tip.]

DIY Guided Telescope Mount Tracks Like A Barn Door

Astrophotography is an expensive hobby. When assembling even a basic setup consisting of a telescope, camera, guiding equipment and mount, you can easily end up with several thousand dollars worth of gear. To reduce the monetary sting a little, [td0g] has come up with an innovative homebrew mount and guiding solution that could be assembled by almost any dedicated amateur, with the parts cost estimated around $100. The accuracy required to obtain high-quality astrophotographs is quite demanding, so we’re impressed with what he’s been able to achieve on a limited budget.

The inspiration for this design comes from an incredibly simple star tracking device known as a barn-door tracker, or Haig mount. Invented by George Haig in the 1970’s, this mount is essentially nothing more than a hinge aligned with the Earth’s axis of rotation. A threaded rod or screw, turned at a constant rate, is used to slowly open the hinge so that a mounted camera tracks the apparent motion of the heavens. As a result, long exposures can show pinpoint images of stars and sharp details of deep-sky objects, instead of curved star trails. [td0g] adapted this technique to drive a more traditional telescope mount, using barn-door-like drive screws on both the right ascension and declination axes. A pair of NEMA 17 stepper motors drive 4-mm pitch Acme threaded rods through toothed pulleys 3D printed from PETG.

Speaking of 3D-printed parts, this build is a good example of judicious use of the technology: where metal parts are warranted, metal parts are used, and printed plastic is relegated to those places where it can adequately do the job. [td0g] has placed the STL files for the printed parts on Thingiverse in case you want to replicate the drive.

The non-linear relationship between the threaded rod rotation and right ascension drive rate usually limits the length of exposure you can reasonably achieve with a barn-door tracker. To adjust for this, [td0g] created a lookup table in firmware to compensate the drive and allow longer exposures. He mentions that the drive will operate for three hours before it hits the end of the screw’s travel and needs to be reset, but if he can manage three hour exposures, his skies must be much darker than ours!

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