Position Angle Corrections

One post-eclipse tip that might be handy. Unless you’re using an equatorial mount, it’s easy for the horizontal alignment for your camera to drift while adjusting your tripod head position during the eclipse.

One result is that your shots appear rotated relative to the true observer zenith (i.e. your local ‘straight up into the heavens’).

You can use the Photo Ephemeris eclipse simulator to correct that as follows:

  1. Setup the simulator for your shooting location on eclipse day and choose C2 or C3
  2. Find a shot that is very close to your chosen contact time, ideally with a well-formed distinct Baily’s Bead
  3. Either visually, or using an onscreen aid, adjust the rotation angle of the photo to match what you see in the simulator.
  4. Assuming you didn’t adjust your head during totality, this angle should be good for all your near/during totality shots and you can apply a batch update

Rough Alignment in Lightroom Classic

You use something like Aequo, which includes an on-screen protractor to fine tune things:

Baily’s Bead at C3 is at ~109°

Fine-tune rotation angle in Develop Module

Double-check with on-screen protractor

Now your shots are consistent with ‘local up’ as seen on the day at your location.


PS. for Partial phase shots, you can use a cusp angle as the reference point, e.g.

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