- Large aperture standard zoom lens.
- Minimum Focusing Distance : 38cm / 15.0inch, Focal Length : 24-70 mm.
- ELD and SLD glass provides excellent correction of all types of aberrations.
- Super Multi Layer Coating reduces flare and ghosting, Equipped with HSM ensuring quiet and high speed AF.
- The rounded 9 blade diaphragm creates an attractive blur.
Product Description
-------------------
This large aperture standard zoom lens covers focal lengths from
24mm and is housed in compact construction. The latest optical
design provides an overall length of 94.7cm /3.7inch. It is ideal
for general photography such as snaps, portraiture and
landscapes. The Super Multi Layer Coating reduces flare and
ghosting. ELD (Extraordinary Low Dispersion) glass, two SLD
(Special Low Dispersion) glass elements and three aspherical
lenses provide excellent correction of all types of aberrations.
Superior optical performance is ensured throughout the entire
zoom range. This lens incorporates HSM (Hyper Sonic Motor),
ensuring a quiet and high speed AF as well as full time manual
focusing capability. This lens has a minimum focusing distance of
38cm/15in and a maximum magnification ratio of 1:5.3. The rounded
9 blades diaphragm creates an attractive blur. It is possible to
attach the included petal-type hood to block out extraneous
light.
From the Manufacturer
---------------------
Compact large aperture standard zoom lens equipped with HSM for
the latest digital SLR cameras
-----------------------------------------------------------------
This large aperture standard zoom lens covers focal lengths from
24mm and is housed in a compact construction. The latest optical
design provides a compact construction and is ideal for general
photography. ELD (Extraordinary Low Dispersion) glass, two SLD
(Special Low Dispersion) glass elements and three aspherical
lenses provide excellent correction of all types of aberrations.
This lens incorporates HSM (Hyper Sonic Motor), ensuring a quiet
and high speed AF as well as full time manual focus capability.
This lens has a minimum focusing distance of 38cm/15in and a
maximum magnification ratio of 1:5.3. The rounded 9 blades
diaphragm creates an attractive blur.
Excellent optical performance
-----------------------------
ELD (Extraordinary Low Dispersion) glass, two SLD (Special Low
Dispersion) glass elements, two molded glass aspherical lenses
and a hybrid aspherical lens provide excellent correction for all
type of aberrations. High image quality is assured throughout the
entire zoom range.
Large aperture standard zoom lens with compact construction
-----------------------------------------------------------
The lens has a compact construction with an overall length of
94.7mm (3.7"). It is ideal for many situations such as portrait,
landscape and general photography.
F2.8 large aperture over the entire zoom range
----------------------------------------------
This lens offers a large aperture of F2.8 over its entire zoom
range. It provides freedom of creative expression and is ideal
for photography indoors or in dim lighting.
Hyper Sonic Motor
HSM (Hyper Sonic Motor)
-----------------------
HSM indicates lenses equipped with a Hyper Sonic Motor, driven by
ultrasonic waves. HSM ensures a quiet and high speed AF as well
as full-time manual focus override by rotation of the focus ring.
Inner focusing system
---------------------
The polygonal shape of a conventional iris diaphragm causes
outo-focus light points to appear polygonal. A rounded diaphragm
is designed to produce rounded outo-focus light points when
opened to near maximum aperture. This creates attractive bokeh
effects in many situations, such as when photographing a subject
against an out-of-focus surface of water from which light is
being reflected.
No Super Multi-Layer Coating (left). With Super Multi-Layer
Coating (right).
Reduced Flare and Ghosting
--------------------------
Sigma's own Super Multi-Layer Coating suppresses flare and
ghosting by preventing reflections within the lens. All DG and DC
lenses in the current Sigma range feature this original
technology. In digital cameras, flare and ghosting may also be
caused by reflections between the image sensor and lens surfaces.
Here too, Sigma's Super Multi-Layer Coating is highly effective,
assuring images of outstanding contrast.
Petal-type hood
---------------
This lens is equipped with a Petal-type hood to block out
extraneous light and reduce internal reflections.
Lens Construction
-----------------
In a conventional lens, focusing requires an extension of the
entire lens or the front lens group. However, to better
accommodate autofocusing mechanisms and closeup photography, a
need has arisen for lenses that do not change their length during
focusing or suffer from focus-dependent variation in aberration.
Therefore, Sigma has developed focusing systems that only move
elements within the lens barrel. These incorporate smaller and
lighter moving lens elements which help improve auto-focus speed.
With their unchanging barrel length and small variation in the
center of gravity, these lenses also enhance balance and
stability for the photographer. Furthermore, since the front of
the lens does not rotate, polarizing filters can be used with
extra convenience.
Lens Construction 14 Elements in 12 Groups Angle of View 84.1
-34.3 degrees Number of Diaphragm Blades 9 Blades Minimum
Aperture F22 (Rounded diaphragm) Minimum Focusing Distance 38cm /
15.0in. Maximum Magnification 1:5.3 Filter Size Diameter 82mm
Dimensions Diameter 88.6mm x Length 94.7mm / 3.5in. x 3.7in.
Weight 790g / 27.9oz.
MTF Chart
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( https://images-na.ssl-images-.com/images/G/01/electronics/lenses/Sigma/SIGMA_24-70mm_mtf_img5_lg._V401491246_.gif )
MTF (Modular Transfer Function) is one of the measurements that
evaluates a lens' performance, and it contrasts sensitivity at
different spacial frequencies. The horizontal axis is in
millimeters and shows the distance from the center of the image
toward the edges, and contrast value (highest value is 1) is
shown in the vertical axis.
The readings at 10 lines per millimeter measure the lens'
contrast ability (red lines), repeating fine parallel lines
spaced at 30 lines per millimeter measure the lens' sharpness
ability (green lines), when the aperture is wide open. Fine
repeating line sets are created parallel to a diagonal line
running from corner to corner of the frame, are called Sagittal
lines (S) and sets of repeating lines vertical to these lines are
drawn, called Meridional (M) line sets.
Distortion
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View Larger Image
( https://images-na.ssl-images-.com/images/G/01/electronics/lenses/Sigma/SIGMA_24-70mm_distortion_img6_lg._V401491243_.gif )
effective distortion: When you take a picture of a lattice
pattern, it will appear as the blue dotted line shows. the red
line illustrates how the lattice pattern will appear in the
actual picture when any lens distortion is taken into account.
relative distortion: In this chart, the horizontal axis shows the
ideal image height (the distance from the center to the edge of
the image [mm]). The vertical axis shows the extent of
distortion. The extent of the distortion is represented by how
much Y, which is the actual image height, grows (or shrinks)
against Y0 which is the ideal image height.
Extent of distortion: D[%]=(Y-Y0/Y0)x100
When you take the picture of a square object, if the distortion
a show a minus value, the image will be seen as expanded
(Barrel distortion). If the distortion a is a plus value, it
will be seen as a recessed (pincushi on distortion). When the
distortion value is close to 0, the appearance of distortion is
very minimal.
Vignetting
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View Larger Image
( https://images-na.ssl-images-.com/images/G/01/electronics/lenses/Sigma/SIGMA_24-70mm_vignet_img7_lg._V401491241_.gif )
The horizontal axis shows the image height (the distance from
the center to the edge of the image [mm]). The vertical axis
shows the a of light in the image (based on the a of
light in the image center being 100%). If the peripheral a
of light is lower than the center, the four corners of the image
will be darker (vignetting).