The 18-270 has a built in motor, so it will AF on the D40.
With that being said, the more zoom length you have, the harder it is to engineer and still have high quality light transmission. Nikon did an amazing job with the 18-200; there was a reason none of the majors made a lens with that much zoom other than as a professional lens until this century.
I haven't actually seen samples of this lens IRL, so I can't comment on the image quality.
With that being said, the more zoom length you have, the harder it is to engineer and still have high quality light transmission. Nikon did an amazing job with the 18-200; there was a reason none of the majors made a lens with that much zoom other than as a professional lens until this century.
I haven't actually seen samples of this lens IRL, so I can't comment on the image quality.
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