Minute angular changes at the image plane affect the anomoly (generate, exacerbate, or eradicate), thus care should be taken
to ensure solid camera mounting which is capable of being adjusted to attain orthogonality.
The best solutions are painfully obvious: If you are planning on doing high-energy narrowband imaging, test the camera before
you buy it... no problem = no fix needed! If rings appear, ensure the imaging train is solid and stable then, if needed, tweak the
camera angle ever so slightly.
Image Info: SBIG STL11000M CCD, Coronado Solarmax90/T-Max, and 30mm blocking filter attached to an Astro-Physics
105mm Traveler via a TeleVue 2X Powermate. Processing was done in Images Plus and final polishing in Adobe PhotoShop.
in high energy narrowband images
This page is not intended as a definitive work, but merely a scratch-pad for listing a few interesting nuances "discovered" with the
Newton's Rings anomaly, as pertaining to high-energy narrow-band imaging. It may (or may not) be padded out with more
information in the future.
Newton's Rings are an interference pattern optical equipment may fall victim to when presented with an extreme narrow-band signal.
Interestingly, my current camera (a monochrome astro-CCD) does not seem to exhibit the problem unless the image covers a
sufficiently large enough portion of the detector array, making "clean" medium resolution images (1290 pixel diameter on the 4008 x
2672 pixel array) possible. Unfortunately, simple flat-fielding (a technique commonly used to remove gradients or other signal
anomalies), does not seem to be a viable solution for correcting the problem, so high-res images are problematic. Any results listed
here (unless otherwise noted) have been gathered from the aforementioned camera, and results for others may differ.
The rings are very dynamic in nature: Subtle changes in position, focus, seemed to create changes in the patterns. Only recently did
I become aware of yet another facet of the rings: the distortion "map" matches far more precisely from frame to frame than I had
previously realized... but with a twist!
The animation below is comprised of two diffused images taken moments apart with the focus changed. Note the shifting rings (and
using the "dust mote" at the pattern's 3 o'clock position as a reference point). At first glance, it would appear that as the illuminated
area expands (via de-focus) the rings also expand:
But now for my epiphany: the pattern is similar but the rings seem to be 1 step out of sync with one another. I then wondered what
would happen if I inverted the signals of one... making a negative: Voila! Check out the match up on the below GIF... the mapping is
nearly perfect! The pattern map in this example is identical but the rings are polar opposites in levels.