A Universal Afocal Adapter

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.

Shooting afocal with an iPhone and the TV-76mm 'scope
Shooting afocal with an iPhone and the TV-76mm ‘scope

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.

Afocal adapter 3D CAD files

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.

Spatter Cone

Watching the current eruption at Kilauea where the western vent fountains and churns leaves one with a practical understanding of how a spatter cone or spatter rampart forms. The blobs and globs of lava land around the vent where they cool. This builds up a substantial edifice around the vent.

Splatters of lava from the western vent Halemaʻumaʻu
Splatters of lava from the western vent Halemaʻumaʻu

The process is illuminating to watch in this current eruption. Every few minutes a large spash or jet of lava escapes the boiling caldron in the middle. The lava spashes across the ground around the vent. At first bright orange, the splash slowly cools and fades to deep red, then dark at it solidifies. The spatter cone is just a little bit bigger.

The spatter cone grows and changes shape daily. Visiting the eruption after a couple weeks one finds the cone drastically reshaped and much larger. Occasional a side will collapse and the process begins anew.

While it might seem fun to get a closer look at the current vent, this idea is also a quick way to die, the gasses and heat would quickly kill anyone who approached too closely.

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Yet Another Volcano Run

Once was not enough, I had to do it again. The allure of lava too much I planned yet another run across island in the middle of the night to see the lava at Kilauea.

The western vent spilling lava into the lake at Halemaʻumaʻu
The western vent spilling lava into the lake at Halemaʻumaʻu

This time Deb would come along, mistakenly agreeing to to 0130 alarm clock and possibly regretting it as she climbed out of bed. Thus we drove through the night passing through the park gates a little before 4am.

A larger crowd greeted us this time. The parking lot was lamost half full and there were more folks passing us on the walk out to the viewpoint.

This trip would feature a bit of moonlight over the caldera rather than the dark skies of two weeks ago, a quarter moon in the eastern sky. I had hoped for a few thin moonlit clouds to use in the compositions, but this did not happen. The morning was completely cloud free over the caldera, and nearly calm, the plume rising striaght up from the lava.

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Volcano Run

The usual plan… A 2am departure from the house, a 4am arrival at Hawaiʻi Volcanoes National Park, at the lava while it is still full dark, enjoy the show through the dawn, then go find breakfast.

Lava Fountain
A lava fountain at the western vent in Halemaumau, Oct 16, 2021

Exiting the vehicle after the long drive I was greeted by a serene silence and bright stars. Orion and the Pleiades were bright and directly overhead. I had to pause and just breathe in the damp forest smells, gazing upwards to the heavens.

There were another half dozen vehicles in the large parking lot at Devastation Trail. I was not going to be alone at the viewpoint, but it was not going to be crowded either. Reports online have mentioned large crowds in the evening, with even the Park Service recommending a morning visit.

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SO2 Monitoring Station

Living with active volcanoes about is made a bit easier if they are properly monitored. The entire island of Hawai‘i is liberally equipped with sensors of various types… Seismographs, tiltmeters, GPS stations, cameras, and gas monitors.

Weather and SO2 monitoring station
A remote weather and SO2 monitoring station

I came across one of these last instruments on a recent visit to Hawai‘i Volcanoes National Park, the new Kahuku Unit at the south end of the island. While walking in the gorgeous natural scenery of the park, this engineer was instantly attracted to a spindly frame of tubes standing in an old corral.

The Kahuku Cross Fence station is part of the NPS maintained Hawaii SO2 Network with stations throughout the park. The data is provided to rangers and posted on the park website to advise visitors of volcanic gas hazards while visiting the volcanoes.

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Mauna Loa Concerns

Like most armchair volcanologists on this island I have been monitoring Mauna Loa more closely lately. The deformation graphs in particular have been? Interesting. I have even gone so far as predicting that we will not get through the year without a Mauna Loa eruption.

An intense earthquake swarm on the NW flank of Mauna Loa
An intense earthquake swarm on the NW flank of Mauna Loa, March 30, 2021

The area of concern has been the western rift zone, exhibiting steady and shallow seismic activity for the last several years. More concerning is the rate of inflation shown in the GPS data, This seems to have doubled in rate around last October.

Then comes today.

An intense seismic swarm is currently occurring beneath the NW flank. Still fairly deep. a few kilometers below the surface, but getting shallower. Magma is definitely moving, a sizable mass moving upwards and emplacing itself higher in the volcano.

This may come to nothing in the near term. Like many seismic swarms it may stop. Just part of the process towards a future eruption some years from now, or never. Or we may be seeing the first step in a new eruption. I will hold to my prediction of an eruption sometime in 2021.

Sit back and watch.