The older lens will fit the d70- they may not meter, but that is also not a problem with a macro setup with a lightbox- just chimp the histogram. Buy as much body as you can afford, but the glass is just as important. The d80 has had great reviews- I have not shot with one. Don't skimp on the glass, it would be like putting walmart tires on your porsche. The older nikon glass is still awfully good- a good used copy of a micro lens would do you well. Leave room in your budget for the tripod, camera plates, flash, lighting, computer programs like photoshop, etc. Just remember, just like computers, as soon as you buy a camera they will release a better one
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