Nikon 15mm f/5.6
WARNING! WARNING! Even if you are not Will Robinson....this link goes to a dubious website....only for adult, discerning, minds.
Cool enough I'd want it even though it would rarely see the light of day in actual use.
Still. That kind of Cool Factor... That can DO things to a man's wallet. I think we'd all understand, either way.
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My concern would be that the widest aperture is only f/5.6. It might be difficult to focus in low light conditions.