Telescope Making – A Darker View

A Battery Caddy for the AM5

The ZWO AM5 telescope mount is a great piece of kit… It integrates very well with software allowing easy computer control, just click and go. The mount tracks wonderfully allowing excellent astrophotos. It is small, does not require a counterweight for smaller ‘scopes, and precise polar alignment is a breeze.

A 3D printed battery caddy on the side of a ZWO AM5 telescope mount

The mount is not without issues… Without a camera integrated into the system the GOTO accuracy is awful, using the mount as a visual mount is frustrating. You really need to have at least a guide camera and the ASI Air computer connected to allow to plate solving and automatic correction of the position at the end of each slew to a new target.

Another issue is that the mount has no concept of cord wrap. It will happily spin around and around as you wander across the sky. In equatorial mode this is not an issue, in alt-azimuth mode this runs the risk of damaging your equipment if you do not notice the power cord getting wrapped up on the mount in the dark.

Yes, I did that.

Binocular Solar Filter

One of the things I brought back from Oregon Star Party was a set of solar filters for binoculars.

A simple set of solar filters for my Nikon binoculars

The filters were from DayStar Filters who had a booth at the star party. I spent a while chatting with the gal running the booth and enjoying the hydrogen alpha views through the ‘scope they had set-up. The Daystar SS60 Hydrogen alpha ‘scope they had on sale was rather tempting.

Battery Corrosion Again

Leaking alkaline batteries, the bane of our portable, battery powered existence. All too many times I have found myself repairing electronic devices damage by leaking batteries, or just junking the gear when the damage is too severe.

Corrosion damage in the base section of a Celestron 8SE mount

This time the device in question was just a bit too valuable to dispose of despite fairly extensive damage.

A Celestron Nexstar 8SE telescope.

Holoholo – A 10.1” f/4.5 Travel Telescope

Living in the islands provides excellent observing for an amateur astronomer such as myself, but there are drawbacks. I do miss the large star parties, getting together with hundreds of other observers to see other telescope setups, to learn, and to share the sky.

The 10" f/4.5 travel scope Holoholo — The 10″ f/4.5 travel scope Holoholo

Thus I have made a habit of traveling to the mainland once in a while to attend one of the larger star parties. This year I will again attend Oregon Star Party. It has been a while, the last time was 2017, the year of the total solar eclipse.

Traveling from the islands to a star party makes it a challenge to bring a large telescope. Last time I borrowed an 11”, not a bad solution, it worked, but it was not my ‘scope. This time I was determined to realize a long considered idea, to build a substantially sized travel telescope. Thus Holoholo was designed and built, a 10.1” f/4.5 travel ‘scope.

A Simple Helical Crayford Focuser

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.

A simple helical crayford telescope focuser — A simple helical crayford focuser

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.

Testing a Mirror

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″.

A textbook Foucault knife edge test image on a 6″ f/4 mirror

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?

Working on it…

Schematics, notes, and tools scattered beside the work area... — Schematics, notes, and tools scattered beside the work area…

Building More Walls

With the big wall completed along the driveway, and a bit of a break over a hot muggy summer, I am again building walls.

Back Yard Wall Excavation — Excavating for a series of terrace walls in the back yard.

This is not the sort of wall between people, I detest those, but rather a real rock wall, terracing the backyard to make the space available for landscaping and other projects. This puts into action a plan that has been brewing for years.

Part of the impetus is that I have a source of rock secured, a very large pile of very nice rock found in a Waimea backyard. One of my co-workers casually mentioned he needed to rid himself of a pile of rock, to which I quickly asked… How much rock?

Getting a Mirror Re-Coated

The classic Cave Astrola telescope has become my roll-out, quick observing session ‘scope, often found in my driveway. I have also used it a few times at darker sites when I expect the weather to be damp or dewy as a Newtonian is more protected.

The restored 8" f/6 Cave Astrola under a dark sky at Kaʻohe — The restored 8″ f/6 Cave Astrola under a dark sky at Kaʻohe

While the restoration job was finished some time ago, I never got around to re-coating the optics. Meanwhile the telescope has seen good service on many occasions as I enjoyed this fun-to-use instrument.

The optics did need some attention… The primary mirror from the Astrola appeared to have not been re-coated since it was made in 1978. Thus the aluminum coating was over 40 years old. While the coating looked bad, it was still serviceable, producing reasonable images.

Still, the loss of light due to the old aluminum coating was probably reducing the effectiveness of this 8″ telescope to something more like a 6″ telescope. I had meant to get it re-coated some time ago, but we know how these things work.

Cave Astrola Restored

Restored Cave Astrola 8" f/6 — A restored Cave Astrola 8″ f/6 Lightweight Deluxe