Hello, I bought this lens recently and I was wondering why such a landscape lens would have washer and Waterhouse stops at the same time. Is the position of a diaphragm something flexible? These two are quite apart. Could be the Waterhouse a later add-on? Does anybody have an explanation or guess about that? Have you seen this before? The serial number is 7456 and is engraved on lens' border as well. I did not evaluate carefully the focal length but it is about 300 mm. Lens diameter is 55 mm.
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