really wide angle zoom targeted at digital users.
doesn't look substantial until you mount it on your camera.
This lens is every bit as big as the Nikkor 17-35mm AF-S. The
butterfly lens hood is built in, and does not remove.
degrees (35mm); xx-xx degrees (D1)
Sigma quietly introduced this wide angle lens in Japan, the grapevine
quickly brought word of it long before it showed up in US stores.
The 1.5x angle of view multiplier built into the Nikon bodies has
digital SLR users craving for wide angle support, and almost every
D1 photographer I know has both the Nikon 14mm f/2.8 and the 17-35mm
f/2.8 AF-S. Yet they still feel constrained at the wide end. Thus,
a zoom that filled the gap at the wide end was widely welcomed.
has been making high quality, unusual optics for some time. One
of my earliest non-Nikon purchases was the 14mm
f/3.5 (now replaced in Sigma's lineup by an almost identical
lens that has a larger maximum aperture of f/2.8). And I used
the 17-35mm Sigma for a brief time before passing it on to my
mother. I knew I'd be looking at the 15-30mm the minute I heard
lens has a maximum f/3.5 aperture at 15mm, f/4.5 at 30mm. The
minimum aperture is f/22 at 15mm and almost f/32 at 30mm. Focusing
reaches as close as 11.8 inches (0.3m). Depth of field markings
are provided for f/5.6, f/8, f/11, and f/16. The design has 17
elements in 13 groups, at least one of which is aspherical.
front element does not move during focus changes, though this
doesn't do you any good, since it sticks out like the bottom end
of a plastic cola bottle and doesn't accept screw-in filters.
A built-in "flower hood" attempts to block off extraneous
light, but don't count on it--the front element curvature is so
extreme that the middle of the lens is extremely prone to catching
a wide angle zoom for the D1. This is the Vietnam Memorial
taken at 15mm with the D1x. I used hyperfocal distance to
keep everything from the Bud beer can in the lower left corner
to the Washington Monument in the distance in focus. Sharpness
is good, corner to corner, and light falloff is nearly nonexistent
on a D1 (but visible in the corners of 35mm slides).
Sigma dealers advertise the lens as taking 82mm filters. This
is misleading. The lens cap consists of two pieces, a ring and
a cap to the ring. The front of the ring has 82mm threads, and
if you're using a digital SLR and aren't zoomed out to 15mm, you
can leave the ring on the lens and screw a filter into it. But
vignetting occurs even on the D1 at the widest focal lengths,
and at virtually all focal lengths on a 35mm body if you put a
filter on the front. (There is also a small "slot" at
the rear that can be used to slip in thin gelatin filters cut
focus ring is wide, but uses the same rubber pattern as the zoom
ring, which is narrower and close to the back of the lens. By
feel alone you can't distinguish between them, but it's not a
over a pound (1 pound 6 ounces), this is a substantial lens. It's
also quite large (almost 6 inches front to back and about 3.5
inches in diameter). The size and weight tends to surprise most
people, as they seem to expect something smaller, especially when
they hear that the lens has a variable f/3.5-4.5 maximum aperture.
doubt you'll be manually focusing this lens other than setting hyperfocal
distance--you get almost no benefit from focusing manually due to
the huge depth of field (which is approximately 1.25 feet to infinity
at f/16!)--but if you do, you'll find the action quite stiff. The
lens is put into manual focus by pulling the focus ring backwards
towards the camera body, and this action is somewhat "reluctant"
on my sample.
on my N90s, F100, F5, and D1x is reasonably fast, but slower than
the Nikkor 17-35mm f/2.8 AF-S. I've never seen the lens hunt on
autofocus. The focusing is quiet, but not "silent wave"
aperture ring is very nice, about the best I've felt on a Sigma.
Click stops are definite, but you can easily set almost an infinite
set of intermediary settings.
front element is very significantly exposed, so you're going to
get fingerprints on this beauty if you aren't careful.
is a mixed bag.
a sharpness and contrast standpoint, the lens does a quite fine
job. On a 35mm body, there's visible softening of the corners wide
open, and the lens starts to show softness again (diffraction caused?)
at very small apertures (f/22 and higher). In the mid-range apertures
the lens is pretty darn sharp from corner to corner. On a D1x, the
lens is sharp at everything but the widest and smallest apertures.
Sigma's excellent performance with previous wide angles, I expected
no rectilinear distortion. After all, the 14mm renders pretty darn
straight lines, even when you place them at the frame edges of a
35mm body. Unfortunately, at 15mm this zoom shows significant barrel
distortion even on a D1x (I haven't done any architectural work
with a 35mm body and this lens, but I would expect the same). What's
"significant?" It might be as much as 2 percent on a D1,
slightly higher on a 35mm body.
expected light falloff in the corners, but this common wide-angle
problem is fairly well controlled on this lens except at the maximum
aperture. What little falloff there is I find pleasing enough not
to be bothered by it. And most of the falloff is at the very edges,
so D1 users won't see much, at all.
extreme front element curvature produces a penalty you need to be
aware of: flare. If any stray light hits that big hunk of
glass, contrast is greatly reduced, making most images unusable.
Worse still, direct hits of light on the element sometimes produce
a strange bit of flare--essentially a hot spot in your image (the
depth of field is so great at smaller apertures and close focus
distances, that at times it can be at the front element, meaning
the light hitting the lens is rendered in the image!). This isn't
just a matter of sun being in the frame. On my D1x, any hot spot
that is rendered "beyond white" has a tendency to produce
a flare spot.
what happens when you don't shade the front element of the lens
in some circumstances. Note that the sun is not in the
frame, but causes the flare in the upper left corner. Note also
the curious colored flares off the bright highlight at the bottom
of the sculpture (green, then pink, then diffused). And, no,
the building isn't massively distorted--that's the Hirschorn
Museum of Modern Art, which is a round building.
Update [1/14/05]: Sigma has continued to bring out new lenses that make the 15-30mm less interesting. Most obvious, the 12-24mm Sigma, which, unlike Nikon's lens of the same focal lengths, can cover the 35mm frame as well as the smaller sized sensor in the Nikon DSLRs.
quality issues. A bit of barrel distortion, edge
sharpness issues on 35mm bodies at the extremes, and contrast/flare
control problems keep this from being a top-of-the-line lens.
If you're expecting this lens to be equivalent to a wider Nikkor
17-35mm AF-S, downgrade your expectations a bit
Lens Cap. Because it slips over the built in hood,
the unique cap has a tendency to come off in my tightly packed
camera cases. Moreover, that strange cap on the cap sometimes
pops off, leaving the front element exposed.
For it's price, this lens performs quite well. When I consider
my star ratings on performance, I consider the cost/benefit, and
this lens delivers well on the positive side of the ledger.
Near Nirvana. Until Nikon introduced the 12-24mm DX, this
lens was the widest zoom you could get to combat the 1.5x angle
of view reduction. If you're scrimping on dollars but need wide,
this lens is your clear choice.