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Review by Klaus Schroiff, published July 2005
Introduction
The Tokina AF 12-24mm f/4 AT-X Pro DX is a representative of Tokina's pro-grade AT-X Pro
(Advanced Technology - Extra Professional) lineup which is especially renowned for outstanding
build quality. The optical design of the lens is a joint effort by Tokina and Pentax. However,
both manufacturers followed a different approach for the mechanical implementation.
The announcement of the Tokina generated some attention because straight f/4 zooms are quite
rare and the specifications of paper look certainly pretty interesting. It is a designated
DX lens which means that it was designed for a APS-C image circle typical for most of
today's DSLRs (except the EOS 1D series). When mounted on a EOS 1D (1.3x DSLR) the borders
start to darken from about 16mm onward.
Depending of the target camera its field-of-view resembles a 18-36mm to 20-40mm lens in
classic terms (35mm film). So far the lens is available for Canon and Nikon APS-C DSLRs.
In the scope of this report a Canon EOS 350D was used for testing.
Typical for all Tokina AT-X lenses the build quality of the lens is excellent. No wobbling whatsoever.
The outer shell is made of high-quality polycarbonate whereas the zoom mechanism is made of metal.
The lens has a crinkle finish similar to some Nikkors giving it a pleasant feel. A weight
of 570g and a size of 84x90mm it's fairly typical for such a kind of zoom. The filter size is 77mm.
The optical construction is made of 13 elements in 11) groups, including 2 aspherical elements
and an SD element. The min. focus distance is 0.30m resulting is a
max. object magnification of ~1:8 at 24mm. The lens features 9 aperture blades.
The lens does not extend during zooming and the front element does not rotate - using
a polarizer is possible without any problems even with attached hood (flower-shaped).
The lens uses a standard micro-motor for auto-focusing. The focusing speed is acceptable - regarding
the ultra-wide character of the lens the motor doesn't get much work anyway. Noise-wise it is
noticeable though not really obtrusive.
Switching between manual and auto-focus isn't done via a small switch as typical for most lenses
but via a focus clutch mechanism by moving the focus ring back and forth. This can be done in
any focus position. Quite nice actually.
Move your mouse pointer in/out of the image to engage the focus clutch mechanism.
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