How wide?
Most of the lenses in this test group are ‘rectilinear’.
That means that straight lines of objects in a scene remain straight in the
resulting image, at least as far as possible. You’re still likely to see some
bowing from barrel distortion, especially at the shortest end of the zoom
range. And exaggerated perspective effects can also make straight lines appear
to curve. These distortions are massively more pronounced on fisheye, or
‘curvilinear’ lenses, like the Sigma 10mm prime lens and Tokina 10-17mm fisheye
zoom.
Even though the two fisheye lenses in the group have a
minimum or fixed focal length of 10mm, similar to many of the rectilinear lenses
on test, they have a much larger angle of view, at 180 degrees on the diagonal.
There are actually two different types of fisheye: circular and diagonal. A
circular fisheye lens produces a circular image at the central region of the
image sensor. Both fisheye lenses on test are of the diagonal fisheye type, which
cover the whole frame, so you get a regular-sized, rectangular image.
A photo shot with ‘rectilinear’
lens
How we tested…
All the lenses in the group were tested on APS-C camera
bodies, but we also used the full-frame Canon EF 17-40mm lens on a 5D Mark II.
We were keen to include this lens, despite it not giving a wide angle of view
on APS-C cameras, as it’s especially good value for a Canon L-series (Luxury)
lens and therefore a tempting proposition if you have a full-frame body or are
thinking of trading up. All lenses were checked for handling, autofocus speed
and accuracy, and all aspects of image quality throughout their aperture ranges
and zoom ranges (where applicable).
Sigma 8-16mm f/4.5-5.6 DC HSM
Rewriting the rule book on rectilinear ultra-wide lenses for
APS-C cameras, the Sigma 8-16mm reigns supreme when it comes to sheer angle of
view. At its shortest 8mm focal length this is 114 degrees compared with the
107 degrees of the Canon EF-S 10-22mm lens. But with the extra comes
compromise.
Sigma 8-16mm
f/4.5-5.6 DC HSM
The lens cap is a two-stage affair, combining a regular
clip-on cap with a sleeve which also has to be removed. You can actually leave
the sleeve on when shooting at the 16mm end of the zoom range, which also
enables the fitting of 72mm screw-in filters or a square filter adaptor. However,
at shorter settings, the sleeve causes extreme vignetting; essentially, you
can’t use popular filters like ND grads at anything other than the longest
setting.
Sharpness proved respectable rather than spectacular but
remains good throughout the whole zoom range, even when shooting with the
largest available apertures. Distortion and colour fringing are fairly well
contained, and vignetting is only noticeable when shooting at 8mm with the
largest aperture of f/4.5. Overall, it’s a good choice if you want to maximise
your viewing angle at the expense of using filters.
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Verdict
·
Price: $650 ·
For: Unbeatably wide angle of view for a non-fisheye lens ·
Against: Filters can only be used at the 16mm end of the zoom
range
|
Sigma 10mm f/2.8 EX DC HSM
Quite chunky for a fisheye prime lens, the Sigma 10mm
delivers a full rectangular image, rather than a small circular picture. It’s
designed exclusively for APS-C cameras so, like all but the Canon EF 17-40mm
lens in this group, it’s incompatible with full-frame bodies. Sigma states a
full 180-degree diagonal field of view but, on Canon APS-C cameras which have a
1.6x crop factor rather than the more common 1.5x as other D-SLRs, it’s closer
to 170 degrees. This still puts it a long way ahead of rectilinear lenses of
the same focal length, squeezing much more into the frame.
Sigma 10mm f/2.8
EX DC HSM
As with any fisheye lens, the trade-off of a larger angle of
view is that barrel distortion is very extreme; it’s this that gives fisheye
images their distinctive look. In practice, the lens works well for giving a
really funky effect in architectural photography, while shooting interiors is
aided by the fast f/2.8 maximum aperture. This makes sharp handheld shots a
real possibility, especially as the depth of field is considerable even at this
large aperture.
Image quality proved sharp right into the corners and colour
fringing was well controlled, while vignetting was only slightly noticeable at
the maximum f/2.8 aperture.
|
Verdict
·
Price: $650 ·
For: Fast maximum aperture of f/2.8; good optical and build
qualities ·
Against: Fisheye effect can wear a little thin, lacking the
lasting attraction of a rectilinear lens
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