[REL] OLC 'Gold' MkIId

[Hitman]

That's what they had on the German subs. Funnily enough, I think I read somewhere that they didn't have it on the American subs, which makes it's inclusion in SH4 a bit odd... or maybe what I read was wrong.

Yes, split prism stadimeters where in the ealier german attack periscope models (Never AFAIK in the observation ones), and you can still see a nice example in the Vesikko. Later models lost the split prism in favour of binocular view, which is a more relaxed experience for the eyes and allows cathing finer details.

But I digress. IRL, as I understand it, the Germans lined up the top of one image with the bottom of the other by turning something on the scope (which caused the images to move together/apart, and also rotated the discs on the Range/AOB finder). Once aligned they'd read the range from the Range/AOB Finder disc and then rotate the prism in the scope so that the two images are side by side instead of one above the other. They'd then twist the thingy again and align the two images bow-to-stern, and then read off the AOB.

Exactly