All three of the lenses are Exakta mount, yes - 58 f2 Biotar, 50 f3.5 Tessar and 35 f4.5 Meyer Primagon. The converter is something made by Canon back in the 60s and named "Lens Mount Converter E". I gather they made converters for other mounts as well, but I'm not sure which.I like this picture a lot!
Are your two aus Jena lenses Exacta mount? Just curious what type of adapter/converter you used on your F-1.