Hello,
Many lenses produced back in the XIX century have no indication of focal distance. However it is very common to find samples with "series" and N° 2, 4 ...
Was that a standard shared among lens makers? Can we say that more than often a lens marked as N°2 will work as a normal lens for a quarter plate, or any other statement alike? Any insight about that?
Cheers
Wagner Lungov
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