Turret finder question

[Ducky]

I know its a turret finder but that's all. On top it says OPTIMUS but no other markings on the barrel. There are 5 turrets with markings 2.8 through 13.5. It has 5 diopter settings from +4 to -4 if I am reading right. There is also a focus ring with feet and mtr. but it turns but does not change focus.
The mounting foot says for, (or tot, or up arrow to, but probably 'for' ) and then Leica.
It came with a fitted unmarked leather case.
I can see clearly through all turrets with the diopter on '0' and the finish is fair.
What the heck do I have here?

 

[Peter_Jones]

Can't help you on who made it, but the focussing should affect it's angle of view to help reduce parallax error. Looks like a useful piece of kit though.

 

[Ducky]

Can't help you on who made it, but the focussing should affect it's angle of view to help reduce parallax error. Looks like a useful piece of kit though.

Thanks, that's exactly what it does. I did not see that at all. The ring is not focal but turns an oval to tilt the foot. Cool. Thanks.