How does this viewfinder work?

[siggy]

I disassembled a Zeiss Ikon Contina cause I thought maybe there was a light meter in there. Well, turns out there are just a bunch of mirrors. What is the purpose of these?

[John Farrell]

The mirrors project the brightline finder frame into the viewfinder. The frame shows the area which will be included in a photograph.

[siggy]

Aha, so it's just to get light for the lines.. For a sec there I thought it could have been a crude rangefinder.

Thanks!

[bobm]

It's what's known as an "Albada" finder and a variation of it was still being used on the Olympus XA3 for one, in the mid eighties.