DIN objectives adaptation for microscope?

General
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FJIMG_20210121_090234
FJIMG_20210121_0902341836×3264 812 KB
FJIMG_20210121_090242
FJIMG_20210121_0902421836×3264 804 KB

DIN threaded JIS objectives are also cool alternative. And there are quite a lot of them on ebay and in old biological labs onshelf.