Tuesday, December 20, 2022

Is More Better? Mars on 12/18/2022.

Seeing was below average this evening, but I decided to see if stacking significantly more images of Mars would produce a better picture than a large, but smaller number. The “lucky imaging” approach captures many frames at tens of frames per second. These frames are then stacked using packages such as AstroSurface, Registax, Autostakkert, etc,. Each of these packages ranks the captured frames by quality. The user then selects the percentage of the frames they wish to stack and process. However, the benefits of stacking decline as the number of frames increases. Stacking 1000 frames rather than 500 makes for a much higher quality image, but as the number of frames increases, the incremental improvement (i.e., the impact on the final image) shrinks.

The first image is from a large stack. I combined several AVIs captured sequentially to produce a large stack of almost 70,000 frames. I selected 45,000 frames for stacking. The second image is derived from 14,000 frames selected from a stack of 25,000 frames.

The differences between these images is subtle. The saturation of the first image (after color balancing), is a little more accurate. Moreover, subtle atmospheric limb clouds (the blue-white haze) are visible. These are missing from the second image. With more frames, I was able to back off wavelet adjustment and reduce the edge “rind” on the left limb of the planet. Achieving similar detail levels on the second image emphasized this rind.

My conclusion is that more is very subtly better. Would this conclusion be the case with a bigger aperture? I hope to test that out next year.

Images captured with a 5 inch Mak and Mallincam SkyRaider SLP.







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