[Misled]

Yes, it's a portrait lens. It's not a macro. It is a very nice lens but won't do what we really want it to for a reef tank macro. You can look into a Sigma 105mm f2.8 or a Tamron 90mm f2.8. Both are highly reguarded and very nice lenses and also can be found on ebay and CL. You can also look at B&H dot com and Adorama dot com for used equipment. Neither lens will auto focus on the D40, but for macro shooting you're better off in manual anyway.