月球南极莫雷环型山不同取样度效果比较 Comparing image scales on Lunar South Pole Moretus Crater
分类: 器材 Equipment, 观测报告 Observations
2025-10-05
Lunar Moretus crater - Savio Fong, Galaxy Scientific Group Tai Mei Tuk observatory
月球莫雷环型山 - 方社长，摄于星河科研社大美督天文台
在9月14日一个视宁度颇理想的早上，试以直焦及加上2x巴罗镜拍摄两段月面南极大特写影片，同时以最优化的参数后期处理，按理后者的每像素取样度已超出理论上实效，同时要在曝光时间、增益及帧度等付出代价，但似乎仍有些许增益。奈奎斯特定理指出取样度应是讯息的2倍，一般说法是二维影像要提升至3倍，但很明显目前的每像素0.05"取样度，已远超视宁度、望远镜成像甚至其他如调焦误差等的量度。所以理论归理论，实践仍是最佳方法。
On the morning of September 14th, under fairly good seeing, I captured two close‑up videos of the lunar south pole—one at prime focus and one with a 2× Barlow lens—then processed them with optimized settings. Although the latter setup exceeded the theoretical effective sampling rate and required compromises in exposure, gain, and frame rate, it still showed a slight improvement in details. According to the Nyquist theorem, sampling should be twice the signal frequency, or about three times for 2‑D imaging. Yet the current 0.05″ / pixel scale clearly surpasses the limits of seeing, optics, and focus accuracy. In the end, theory aside, practical testing still proves best.
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Right image
2025-09-14 04:31
Celestron EdgeHD14
SkyWatcher EQ8R Pro
ZWO ASI678MM
image scale 0.11"/pixel
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Left image
2025-09-14 05:08
same setup + Carl Zeiss Abbe Barlow 2x
image scale 0.05"/pixel
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