Product Description

18-200mm F3.5-6.3 II DC OS HSM lens is ideal for travel photography with a compact construction and length of just 87.7mm. This lens features FLD (F Low Dispersion) glass elements, which have the performance equal to fluorite glass and SLD (Special Low Dispersion) glass elements providing excellent correction of color aberration.

From the Manufacturer

Compact High Zoom Ratio Lens with OS (Optical Stabilizer)

This 11.1x high zoom ratio lens incorporates Sigma's original OS function and offers a broad shooting range from wide angle to telephoto. The latest optical technology enables easy handheld photography with a compact construction and length of just 3.5”, making it ideal for various scenes such as landscape, general photography and sport. This compact construction guarantees excellent mobility. FLD ("F" Low Dispersion) glass elements, which have performance equal to fluorite, SLD (Special Low Dispersion) glass elements, and aspherical lens elements provide high image quality throughout the entire zoom range. The HSM (Hyper Sonic Motor) ensures fast and quiet auto-focusing.

*Sony and Pentax mounts are not incorporated with OS function.

*For Pentax mount, if the camera body does not support HSM, auto focus will not be available.

Compact whilst keeping high optical performance

The SIGMA 18-200mm F3.5-6.3 II DC OS HSM is the successor to the SIGMA 18-200mm F3.5-6.3 DC OS/ HSM which was launched in June 2007. This lens features the latest optical technology including FLD glass elements and aspherical lens elements, making it compact with a length of just 3.5” whilst keeping high rendering performance. This compact construction guarantees excellent mobility.

Superior image quality

One FLD ("F" Low Dispersion) glass element, which has performance equal to fluorite, and two SLD (Special Low Dispersion) glass elements provide excellent correction for color aberrations. Two glass mold aspherical and a hybrid aspherical lens element ensure excellent correction for all types of aberrations. Together they provide a high level of optical performance throughout the entire zoom range.

*FLD glass is the highest level low dispersion glass available with extremely high light transmission. This optical glass has a performance equal to fluorite glass which has a low refractive index and low dispersion compared to current optical glass. It also benefits from high anomalous dispersion.

These characteristics give excellent correction for residual chromatic aberration (secondary spectrum) which cannot be corrected by ordinary optical glass and ensures high definition and high contrast images.

No Super Multi-Layer Coating (left). With Super Multi-Layer Coating (right).

Super Multi-Layer Coating

The Super Multi-Layer Coating reduces flare and ghosting as well as providing sharp and high contrast images throughout the entire zoom range. 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.

No Optical Stabilizer (top). With Optical Stabilizer (bottom).

Sigma's own unique OS technology

The OS system offers effective correction of approximately 4 stops, making it ideal for handheld photography of various scenes such as travel, general, and sport.

*Sony and Pentax mounts do not incorporate Optical Stabilization.

Hyper Sonic Motor

High speed and quiet AF

HSM indicates lenses equipped with a Hyper Sonic Motor, driven by ultrasonic waves. The HSM (Hyper Sonic Motor) ensures fast and quiet auto-focusing.

* For Pentax mount, if the camera body does not support HSM, auto focus will not be available.

Rounded diaphragm

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.

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.

Specifications

Lens Construction 18 Elements in 14 Groups Angle of View (for SD1) 76.5 - 8.1 degrees Number of Diaphragm Blades 7 Blades(Rounded Diaphragm) Minimum Aperture F22 Minimum Focusing Distance 45cm / 17.7in. Maximum Magnification 1:3.8 Filter Size Diameter 62mm Dimensions Diameter 75.3mm x Length 87.7mm / 3.0in. x 3.5in. Weight 490g / 17.3oz.

MTF Chart

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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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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 amount show a minus value, the image will be seen as expanded (Barrel distortion). If the distortion amount 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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The horizontal axis shows the image height (the distance from the center to the edge of the image [mm]). The vertical axis shows the amount of light in the image (based on the amount of light in the image center being 100%). If the peripheral amount of light is lower than the center, the four corners of the image will be darker (vignetting).