Derotation in Astrophotography [Field Rotation]

Derotation in Astrophotography is Amazing

I learned something new this weekend.  I learned about a technique in astrophotography called Derotation.  I’m amazed at what a little imagination and scientific skill can accomplish.  Grischa Hahn, had the bright idea to reduce motion blur in photos of the planets.  Especially those with days slightly greater than 9 Earth hours.  Derotation in Astrophotography is a powerful technique and is brilliant.  Derotation is built into his software called WinJupos, is an algorithm which does the following:

  1.  takes the frames of a group of images or video and flattens them out into a cylindrical shape.
  2.  Compares those cylinders to one another and matches them up
  3.  takes each aligned cylinder and recreates the image of the planet.

Is it really 3 easy steps, no and when you add a database of planetary positions, this becomes an indispensable tool in Astrophotography.

 

Jupiter no Derotation
Telescope: Meade EXT-125
Camera: Google Pixel
Jupiter with Derotation
Telescope: Meade EXT-125
Camera: Google Pixel

Here’s a photo on the left of Jupiter I processed without derotation.  I was happy to see the GRS (Great Red Spot) but could not bring out the detail beyond what you see here.

On the right is the derotated picture and the details are much sharper.  I was also able to brighten the photo in the process.

I’ve tasked myself to derotate many of my previous photos of Saturn and Jupiter.  So far with little success.  I’m learning that I need to improve my video capture techniques.  So look out for more of my work in the near future.

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