CV 90mm external viewfinder

[thmk]

Hello,
I just got a CV 90mm external viewfinder for my Bessa T and I wonder what the inner markings are for. The finder itself can be parallax corrected manually so now I wonder why there are 2 "frames" to be seen. Can anyone help me out?

Cheers
Thomas-Michael

 

[thmk]

Stupid me... I knew I missed something - the search function!!! 😀 I was so happy that it arrived before the weekend. Maybe time for some vacation...

Many thanks
Thomas-Michael