The picture above was presented on Universe Today site like an interesting optical illusion: Astrophoto: Moon Optical Illusion by Lupuvictor .
Optics: Celestron C8-Newtonian telescope, plossl 20mm, 2x Barlow
Mount: CG5 (EQ5)
Device: Sony CX105 at 8x optical zoom
Total magnitude: 800x
Location: Baia Mare, Romania
Processing: video captures, FastStone Image Viewer
Copernicus (93 km) is stunning beautiful. I added sharp and contrast to some pictures.It is a beautiful crater, in fact so stunning that last photo cropped, is producing an optical illusion. Sometimes gives the feeling that there is not a dip, but an elevation,a bump. I do not know how many are going to see it that way, but I asked someone, and saw the same as me.
There are several other craters that look like lumps or bumps. In fact, all can give this impression, and look like craters, and bumps as well, depending on the direction from which you think comes the sunlight.
Last picture of the crater Copernicus, is turned upside down at 180 degrees and is a crop.
We analyze the last picture: if you believe that sunlight comes from the southwest, it is seen as a deep crater.If you think the sunlight comes from the northeast, it is no longer seen as a crater, but as a swelling .