Tech
Specs
Focal
Length: 24-105mm
Dimensions:
4.3 x 3.5 in.
Weight:
31.2oz.
Maximum
Aperture: f4
Minimum Aperture: f22
Diaphragm
Blades: 9
Front
Element: non-rotating, non-extending
Optical
arrangement: 19 elements in 14 groups
Autofocus
Mechanism: Sonic Drive
Closest
Focus: 17.7 in
Maximum
magnification: .22x
Filter Size: 82mm
Background
At
Photokina 2012, third party photographic lens maker Sigma has
reinvented its business model with a new Global Vision, whose focus
is, among on other things, producing optics that can go toe-to-toe
with the manufacturer products instead of serving as a poor man's
alternative. To that end, Sigma has churned out a lot of drool-worthy
gear in the past two years. However, there was a major hole in
Sigma's revamped lineup: a fixed aperture standard zoom for full
frame. Cue the lens we're reviewing here today: the Sigma 24-105 f4
DG OS HSM Art. With a long history of making fast to semi-fast fixed
aperture zooms, Sigma has a lot of background in such optics and,
with a new Global Vision, a stronger drive than ever to make
class-leading products. So, does the 24-105 f4 OS Art deliver the
goods? Well, read on to find out!
Build
Quality: 5/5
The
Sigma 24-105 f4 OS Art is built to the standards that were, even just
a few years ago, reserved for manufacturer optics. Constructed out of
Sigma's exclusive Thermally Stable Composite (TSC) material, which
feels a lot like metal but whose formula is a closely-held corporate
secret, the lens has a decidedly solid feel to it. In addition, the
lens is inner focusing, which means that there is no moving/rotating
of the front element when focusing, which is good for people who like
to use polarizing filters. As for the rings, both zoom and focus
rings are rubberized, highly textured, and come across as having that
'just right' balance between ease of movement and lack of slop. For
some people, the dual cam inner design may be of a concern but, at
least in-hand, there's no wobbling whatsoever. However, I cannot
vouch for this lens when shot in harsh conditions as it not marketed
as weather resistant.
Survivability
This lens is focused by a built-in motor and stabilized by electronic gyros which will die eventually. To protect your investment, buy factory new and register your warranty with Sigma, which will fix your lens for free should something go wrong during during the warranty period and for a cost out of warranty so long as parts are available.
See also: Weather Resistant Sigma Lenses
AF Performance: 5/5
Focus on the Sigma 24-105 f4 OS Art is as fast, accurate, and silent thanks to Sigma's Hypersonic Motor (HSM) technology, which is the company's version of a ring type sonic-drive AF system. As for tracking, the lens had no problems with birds in flight (see samples) on the D700. As with all ring-type AF, the lens has full time manual override, which allows for instantly overriding the AF simply by turning the focus ring, no need to flip switches. In reality, the AF/MF switch is more of an AF/AF Disable switch.
At 24mm
At 35,mm.
At 50mm.
At 70mm
At 105mm
Optics: 5/5
Sharpness (Note: on DX, consider the mid frame here to be the
corner)
By looking at all the test images, a pattern emerges: the
Sigma 24-105 f4 OS Art is as good as it will get right out of the
gate at f4 across the focal range and frame, which means that
stopping down will only increase depth of field as sharpness won't
noticeably improve. Needless to say, that's a very, very good thing.
For nit pickers, there is some slight softening in the corner of the
frame on a FF sensor when viewed at 100%. For the non-pixel peepers
out there, this will be impossible to notice in real life shooting
and presentation.
Stabilizer
Mechanism
The Optical Stabilization (OS) feature is different than
everything reviewed here in that there is no absolute way to quantify
how well it works since the amount of camera shake is determined, by
and large, on the inherent steadiness of the photographer's hand and
shooting technique. That said, I was easily getting steady pictures
of ½ second long at 105mm. Additionally, the stabilizer is
absolutely silent in operation
Vignetting
There
is some shading with the Sigma 24-105 f4 OS Art wide open at f4, with
it being most pronounced at 24 and 105mm. A stop down, the shading
decreases dramatically and disappears by f8. At middle focal lengths,
vignetting disappears by f5.6.
Distortion:
There is some distortion here, but nothing out of line
as for what one can reasonably expect for such a lens.
CA
Nil here.
Macro
While anything but a dedicated macro lens (.22x is its
maximum magnification), the Sigma 24-105 f4 OS Art is still pretty
good for capturing larger macro subjects, like flowers, especially
with today's cameras and all of their megapixels, which allow for a
lot of cropping. The above images are the full picture (albeit at a reduced resolution) with a 100% crop.
Flare/Ghosting
This lens is remarkably resistant to flaring.
Astrophotography
Infinity focus is not
exactly infinity here, which means that you will need to fiddle with focus on a bright star with live view at full magnification.
Bokeh
With its 9-blade, rounded design, out of focus blur (bokeh) is buttery smooth.
Value:
5/5
Ah, here's the tough
one as, at $900 new, the Sigma 24-105 f4 OS Art is not cheap by any
means. On the other hand, when one looks at the manufacturer
equivalents, this lens looks decidedly economical as the equivalents
from Canon and Nikon, (Sony has no equivalent) both are a lot
pricier. For both Canon and Nikon shooters, you get a dust seal at
the mount on both of your camera makers' lenses (and an extra 15mm
for Nikonians) but the question is this: do you plan to shoot in
conditions that would warrant the rubber gasket at the mount that
will add $250 and $400 to the price of the Sigma, respectively?
Competition
To
put it plainly, the standard zoom lens is the most crowded segment on
the market for the simple reason that such lenses are just so doggone
useful. The direct competitors in the mid aperture stable from the
manufacturers already addressed, there are a lot of other
alternatives, too. For starters, there are the 24-70 f2.8s that are,
again, made by just about everyone (Sigma makes one, too). Obviously,
these lenses trade about 30mm of reach for an extra stop of aperture.
The extra brightness is often offset with the cost of losing the
stabilization, which often results in a wash at the checkout. The
exception here: Tamron, which makes a stabilized 24-70 f2.8. Current
models aside, there are out of production lenses in this focal range
in both f2.8 and f4 versions, some with and other without
stabilization, on the used market. Again, there's a tradeoff for that
lower price: questionable support from the manufacturer. Long story
short, if your old lens breaks, there may not be any parts with which
to fix it, which will essentially turn your lens into an expensive
paperweight.
My advice: with an AF lens (especially when
paying this much), it's safer to buy new and the main consideration
should be the f2.8 vs. f4.
Conclusion: 5/5
There's no doubt about it: the Sigma 24-105 OS Art is quite a lens. Sturdy build, excellent mechanics, great optics, and all at a bargain price when compared to manufacturer alternatives combine to make this lens a very attractive buy. In the end, the main consideration when buying a standard zoom comes down to this: a shorter f2.8 or a longer f4 with a stabilizer. If you decide to go with the f4 optic, there's no reason not to buy the Sigma 24-105 f4 OS Art as it really does represent a package that can cover 95% of the photographic applications of the people reading this review. Needless to say, I can't wait to see what Sigma has over the proverbial horizon!
Samples:
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