Part of the Nikkor's additional weight is undoubtedly down to its slightly
faster optical performance at the telephoto end. It sports a focal ratio of
f3.5~5.6, compared to the f3.5~6.3 of the Sigma and Tamron models.
In terms of build quality, the Nikkor also feels (and looks) to a much
higher standard than its cheaper rivals. It's more solid with smoother
mechanics delivering a greater impression of confidence in use. That said,
the Sigma and Tamron models aren't bad, but place the three side by side
and the Nikkor is definitely the classiest.
We're pleased to report all three employ internal focusing with non-rotating
end sections - important for anyone who uses polarisers, although obviously
the Nikkor's wider thread will incur higher-priced filters. Thankfully,
all three lenses were supplied with hoods.
The Nikkor's SWM motor resulted in almost silent operation, compared
to the quite audible focusing motors of the Sigma and Tamron lenses; the
Tamron in particular was the noisiest of the three and you could especially
hear the gearing when manually focusing. While the Nikkor was by far the
quietist though, it was only slightly faster at focusing than its rivals.
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