sabbath999
Contributor
The D40 does not allow one to control the aperture with the aperture ring on the lens. So some lenses will not work, but I *think* they would have to be the old manual lenses.
I assume you mean they won't work with an underwater housing?
"Non G" lenses work just fine on a D40, as do virtually all other Nikon lenses... they just don't meter or autofocus. Virtually every Nikon lens that will fit an original circa 1960 Nikon F will "work" on a D40 (manual focus and exposure... non-AI lenses need to be stopped down as well, but technically they do "work" although the non-AI tabs can munch the top of the camera if you are not careful... so better to stick with lenses made in the mid 1970's or later). G or not G, doesn't matter, they work fine (again, though, no meter). The only ones that simply will not work are a couple of really rare and bizarre fisheyes that extend back into the body and require a mirror lockup, and those awful Pronea lenses.
Third party lenses may or may not work. Sigma's HSM lenses work great. The new Tamrons with internal motors work great.