Call or go online to KEH.com
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My wife uses D2X's. We have several really Nikkor AFS zooms (28-70, and a 35-105), a 28 WAL, standard 35mm, and a really good 2.4 50mm. They can get expensive, so make sure you go into detail with a rep.
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You can also set the D5000 to "fine", and use a 35mm and then crop the image. Same thing with a 50,or even a zoomer. It's the image pixel count that presents any problems.
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The best bargain is usually a 28-70 zoomer.
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PS... The Keh staff are very well qualified.