Tuesday, May 25, 2021

Lunar Eclipse Imaging - Prep

Finally, an eclipse again - this time a lunar eclipse. I planned early and ended up preparing 4 different ways to image it:

  1. Closeup - using a tracker and Lunar Eclipse Maestro
  2. Ultra wide angle timelapse
  3. With the Unistellar eVscope
  4. Manual widescapes

Turned out that I had a lot to prepare:

1. Closeup
The first challenge was that Lunar Eclipse Maestro only runs on MacOS and not beyond Mojave. But Xavier Jubier (the author) told me that I can run it in a VM.

Enter VirtualBox from Oracle. Luckily I found great instructions on how to install MacOS Mojave on VirtualBox. Beyond that I had to:

  • Pass the required USB ports to the VM. Which is fairly easy, you have to connect the USB devices and then select those devices to be available in the VM.
    Note: DON'T select the external hard drive that runs the VM or the keyboard USB ports here!!!
  • The time on MacOS was constantly off. I had to install guest additions to fix that. Also, the calendar was by default set to "Persian" - had to change it to "Gregorian".
Not being able to use my TOA-130 scope (I couldn't image the eclipse from our backyard but ended up driving up to Lick Observatory) I borrowed a 500mm lens from borrowlenses.com. And that was way too heavy for my Vixen Polarie. So, I ended up upgrading to an iOptron SkyGuider. The fast and accurate polar alignment using an iPolar and the load limit made it a great fit.

Figuring out the SkyGuider was a breeze (though first I received one where the iPolarie wasn't focused properly which made polar alignment impossible).  Having a counterweight and a sturdy ballhead was great for stability. I kind of wish that there was a mobile version of the polar alignment software - that would make the SkyGuider even more portable. Though most of the time when I take tracked images, I have a laptop with me anyway.

As always, battery power of the Nikon's concerned me: the batteries probably wouldn't last the entire night and I would need to remember to change them. A couple of months ago, I tried out the power supplies from Pegasus Astro. But they failed to power the D750 cameras (it worked on the D7000). When I tried these out again, I connected one of them directly to a 12V battery (by accident!) and ... it worked!!! Seems like the power of the power supplies from Pegasus Astro isn't powerful enough for the D750. But that was great. I purchased another batter coupler and could not power both Nikon's from the 12V battery!

Setting everything up in our backyard.


2. Wide angle
As so often, I wanted to take a timelapse using the 14-24mm Nikkor lens. I wanted to start the timelapse at midnight and end when the moon sets at 6am. In this time, the moon moves from 151° Azimuth / 22° Altitude to 243° / 0° = 90° horizontal and 22° vertical. Using a field of view calculator, the D750 covers 90° horizontal and 67° vertical at 18mm focal length. So, I'll use that.
As the brightness will change significantly (lunar eclipse and dawn) I will use the "holy grail" function of qDslrDashboard to adjust the exposure time and ISO automatically. As always, I will use the LRTimelapse Pro Timer for shooting.

3. Unistellar eVscope
Being able to watch the eclipse up close on a tablet should be convenient. Especially when it will be cold and we can do it from inside the warm car!

4. Manual Widescapes
Finally, I will use my 135mm and the 85-300mm lens for manually composing and shooting. Just using a tripod and remote shutter.

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