I suspect the issue is more that all of them suffered from balsam separation and those with clear glass have been re-cemented. Usually by some joker like myself who doesn't have the proper equipment to ensure the alignment is as good as new, which can be an issue re-cementing a 5-glass block like mine (my pics are quite sharp so I guess I didn't mess up too badly).
It might be a safer bet to go with a Protar VII if you want a vintage triple-convertible.
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