This started as a twenty-five second exposure, ten frames per second at 1/500 sec. drift scan.
Two hundred thirty-six frames, aligned and stacked in registax at 50% quality. I wanted as many frames as possible, and the quality was good overall. After stacking and expanding the image and processing with wavelets, I opened the saved image in Photoshop. Here I ran a Gaussian Blur to remove the blockiness introduced by high values of wavelets. Then two iterations of unsharp masking sharpened the image and preserved the details. I cropped the result to just display Copernicus. This holds up even enlarged 500%, and you can see the three central peaks in the crater. Right-click and select view image for the full size.
The close-up of Copernicus has been enlarged 400% and unsharp masked four times to bring out the crater walls and peaks.
Here’s a view from the Lunar Orbiter: