When you want to see the stars, find someplace dark
Due to a plan that failed I ended up with a borrowed astro camera for a couple weeks. Since I have it I may as well play with it a bit.
The camera is the ZWO ASI2600MC Pro, a one-shot color camera specificaly for astrophotography. I have the ASI1600MM Pro a monochrome camera set up with a filter wheel, but have never really had a chance to use one of the modern one shot color cameras.
Continue reading “Using the ZWO ASI2600MC Camera”For some reason I have gotten along without a focus mask for the TV-76. Need to fix that… Done.
Just a quick project, about half an hour to design and four hours printing. First print a pleasing success, a completely functional part.
A Bahtinov Mask is used to get a precise focus, something I wrote about a few years back.
For this mask I used a public bit of OpenSCAD code from Jens Scheidtmann to generate the mask pattern, just tuning it for the correct sizing and performance with the TV-76. I added my own version of the support collar, making it a bit neater with fillets and properly sized to slip over the TV-76 glare shield.
You can download the SLT file for the mask from Cults3D if you need to print your own.
The part is one of a half dozen parts I have designed and printed over the last few weeks to reassemble the photo rig. A new guide camera mount, a mount for the ASI Air computer, a new glare shield for the guider, etc., etc… The utility of 3D printing a game changer for me.
How simple can a focuser be?
This has been a bit of a design challence for me… Just how small, how simple, can I make a focuser and yet still provide excellent usability. My latest Helix 1-14 design is my best yet.
As my 3D printer design skills improve I applied lessons learned and the unique capabilities of an FDM printer to the problem of a focuser. After a bit of a journey I have arrived at a design I can consider finished. Is it the final design? I may tinker some more, but I am satified for the moment.
The design is based on a few ideas from here and there, products I have seen or used, internet postings from others faced with the same challenge. I am not one for just printing someone else’s design, I rarely do that, I want to do my own, and maybe make it better.
Continue reading “A Simple Helical Crayford Focuser”
As I have observed lately, most of the small telescope mirrors available right now are out of China, most of those produced by one company, Guan Sheng Optical or GSO. If you want a small mirror, say a 6″ or 8″ mirror, there is not a lot of choice, the mirror makers in the US generally do not do anything smaller than 10″.
The GSO mirrors range from decent to pretty bad, with no way of knowing what you will get when you order, just luck of the draw.
But how do you tell?
Continue reading “Testing a Mirror”A couple weeks ago at the volcano I let quite a few folks take imagery of the lava using the afocal technique, simply holding the phone up to the eyepiece. This works rather well as the phone uses a lens much like the human eye, about the same aperture.
The only real issue is holding a phone in just the right spot. Folks wanted video, but holding the phone steady is a real challenge. I had thought of making something to do this many times, last weekend I did it.
A session of playing around in 3D CAD resulting in a couple bits of clever plastic printed with the 3D printer… Done.
There are commercial solutions for this available, quite a few actually. But most of these are intended to adapt to a single phone, using some sort of clamping arrangement that you have to setup for a particular phone. I envisioned something that was more universal, quickly adapting to any phone.
The method I chose was a sliding magnetic platform that holds the phone. Just a simple shelf actually, set the phone on it and slide until you get it lined up. The base piece is printed with a recess into which a steel plate is set. The slider has three 8mm x 2mm neodymium magnets to securely grab the steel plate.
It took a bit of work to cut and file the steel plate to neatly fit the base, a bit of inlay work. Otherwise making the piece is quite easy. The only design issue is that this adapter is setup to fit a single eyepiece, a Televue Panoptic 27mm, and cannot be easily adapted to others.
The 3D CAD files are linked below. I have included the SCAD source file to allow tinkering with the design, possibly adapting to a different eyepiece. Both parts should be printed with support on, the pockets for the glued bits will have to be cleaned out, the resulting rough surfaces just right to recieve epoxy.
At the Keanakakoʻi Overlook I was able to test the adapter with a variety of different phones, both iPhone and Android, graciously lent to me for my experimentation. OK, the owners may have wanted a few lava photos. There was no difficulty using the adapter other than a moment or two needed to line up the camera with the exit pupil of the eyepiece. The result was more than a few smiles.
I wanted a smaller, lighter finder ‘scope for the Astrola, and I wanted right angle to stop straining my neck!
I have been using a big Orion 9x60mm finder on the Astrola, the only telescopic finder ‘scope I have among the Telrads. It is nice, with a bright image that shows many faint fuzzies. It is also huge, and very heavy, it is also straight through, requiring one to crane your neck around to view through it on the Newtonian ‘scope.
A small, lightweight finder was in order, a perfect project for a newly arrived 3D printer.
Continue reading “A 3D Printed Finder ‘Scope”
As an evening pastime in these COVID restricted days I have been delving into the past again. Again reading the work of an amateur astronomer from long ago.
I had previously read through the work of Rev. Thomas Webb, a vicar and amateur astronomer active in the late 1800’s. Webb frequently refers to the work of a yet earlier observer, Capt. William Henry Smyth.
Retired British Navy Captain Smyth was a backyard observer, gazing at the stars with a 150mm refractor from a garden behind his home in Bedford England. His telescope was quite good for the time, made by Tully of London, the best money could buy. This telescope was eventually purchased by the British Government to be used in the 1874 transit of Venus expedition to Egypt and the 1882 Venus transit in Jamaica. It now sits in the collection of the Science Museum, London.
Smyth published two volumes on astronomy in 1844 under the title A Cycle of Celestial Objects . Volume II of this set, commonly called The Bedford Catalogue or The Bedford Cycle, contains descriptions of more than 850 double stars, clusters, and nebulae, serving as a guide to what may be observed with a small telescope. The Bedford Catalogue became the standard at-the-telescope reference for other amateur observers for many decades until it was generally replaced by Webb’s Objects for Common Telescopes.
Continue reading “A View from the Past”