Isaac Kunen

Professionally, I’ve built Snowflake’s Snowpark, Tableau Prep, SQL Server’s geospatial support, and more. Recently, I’ve been learning physics at the UW and teaching at North Seattle College.

Personally, I’m a father, a husband, a cellist, a photographer, and a tinkerer.

All opinions expressed here are mine alone: you can’t have them.

2 minute read

Not too long ago, I bought a telescope. I guess that makes me an amateur astronomer.

If you buy a camera, you are a photographer. If you buy a flute, you own a flute.
- Bob Kolbrener

So maybe I just own a telescope.

I certainly need some help when it comes to choosing things like eyepieces, so I was thrilled to come upon a very thorough list of eyepieces assembled by Starman1 (Don) over at Cloudy Nights.

But a spreadsheet is one thing—a viz is better. My take at an explorative viz is online over at Tableau Public. (I wish I could figure out how to embed something here, but all I can manage is a screenshot.)

eyepiecesGo ahead and tweak the parameters to find the eyepiece you're looking for. Some details on how I built it are below the fold.

Build Details

 

Don's data are pretty clean, but I did have to massage them a bit:

  • A lot of missing values were null, but some were listed as "?". I normalized them all to null so I could treat numeric values as numeric.
  • There are some eyepieces available in multiple formats that I had to split up and pivot.
  • There were some zoom and multi-focal-length eyepieces that I had to figure out how to handle.

All of this was straightforward to see and handle using Project Maestro. I'd recommend it even if it wasn't my baby.

I did have to make a few choices in the viz:

  • My two primary axes represent the things that seem most important to me: focal length and the amount of the sky you can see. As focal length increases, the magnification decreases, and the resulting trend towards larger FoV is clear. Still, there is a wide variation depending on eyepiece construction.
  • I used mark size to indicate eye relief. This is super important to me because I wear glasses; anything less than about 20mm makes it hard.
  • Color indicates price; everyone cares about price.
  • I had to decide how to handle zoom eyepieces. I show them as their average focal length. Full details are in the tooltip:
    tooltip

Suggestions for improvement are welcome. Enjoy!

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