I recently got a great deal on a Mitutoyo planapo 5x from Robert O'Toole, bought with the understanding that the front surface was ruined for photography and it was a for parts purchase. I needed it for some basic testing and it's been perfect for that, but there's no question that front surface isn't right. Here's what it looks like in the hand:
Under the microscope the etching is pretty obvious, and actually kind of beautiful:
FoV is about 6mm, shot on my Wild M420 with the Makrozoom lens (hence the CA everywhere) and with my Canon Rebel T6, stacked from 19 shots.
Etched mitutoyo planapo 5x surface
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