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Maximum reproduction ratio

1:6.6 maximum reproduction ratio -> 10mm object will take up 1.515151515151 (sorry had to do that) mm on the sensor.

DX sensor on D40 23.7mm -> 3008 pixels so 1.51 mm -> 192 pixels -> about 1in for a 200dpi print.

So with the 50mm 1.8 AF-D lens if you shoot at the closest distance (about .5m) a 1cm object can be printed at 1in decently. Not that you would want to use this lens that way...
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