Product Description

The Sigma 105mm f/2.8 EX DG OS HSM Macro Lens for Nikon DSLR Cameras offers advanced performance of close-up photography. The OS (Optical Stabilizer) system enables handheld close-up photography. A Special Low Dispersion (SLD) lens and one high refractive index SLD lens provide excellent correction for all types of aberration and distortion. A floating focusing system moves two different lens groups in the optical path to different positions. This system compensates for astigmatic aberration and spherical aberration and provides extremely high optical performance from infinity to 1:1 Macro.The Super Multi-Layer Coating reduces flare and ghosting, providing high contrast images. It is also possible to use this lens with Sigma's APO TELE CONVERTERS. The HSM (Hyper Sonic Motor) ensures quiet and high speed autofocus as well as full-time manual focus capability. This lens features a splash proof design for use in harsh conditions and a rounded 9 blade diaphragm creating an attractive blur to the out of focus areas of the image.

From the Manufacturer

High performance, large aperture medium telephoto macro lens with OS (Optical Stabilizer).

High performance, large aperture medium telephoto macro lens with OS (Optical Stabilizer). SLD glass provides good control of aberration and the floating inner focus system ensures high rendering throughout the focusing range. By using Sigma's APO Tele Converter, it is possible to take photos at greater than 1:1 magnification. HSM ensures a quiet and high speed AF as well as full-time manual focus override. This lens has a rounded 9 blades diaphragm which creates an attractive blur to the out of focus areas.

Large aperture medium telephoto macro lens

This medium telephoto macro lens allows you to maintain an appropriate distance from subjects while still getting close up photos. Since the working distance at its closest focusing position is 142mm, shadows of the lens and camera will not affect photography making it suitable for taking photos of subjects, such as flowers, under natural lighting conditions. In comparison to the Sigma 50mm and 70mm macro lenses, the main subjects can be defined with perfectly smooth and blurred backgrounds.

High rendering performance

The lens power layout produces excellent optical performance. High refractive index SLD (Special Low Dispersion) glass corrects chromatic aberration, spherical aberration and field curvature. It ensures high rendering performance at all shooting distances. The Super Multi-Layer Coating reduces flare and ghosting, maintaining quality images with high contrast.

Handheld photography with ease

Sigma's OS (Optical Stabilizer) system offers effective correction of approximately 4 stops. As the stabilization effect is visible through the viewfinder, it aids composition and accurate focusing.

* The OS effectiveness will gradually decrease as the shooting distance becomes shorter.

Floating inner focusing

This lens incorporates floating inner focusing which moves two lens groups separately. This minimizes aberrations which occur as shooting distance changes, and enables stable rendering of the image from infinity to 1:1 magnification. This also corrects image distortion, especially when taking close-up pictures. Since focusing does not change its overall length, this lens is easy to hold and use.

Quiet and speedy AF

HSM indicates lenses equipped with a Hyper Sonic Motor, driven by ultrasonic waves. HSM provides quiet and high speed AF. It is also possible to use full-time manual focus, even if the lens is set to autofocus.

Rounded 9 blades diaphragm

This lens has a rounded 9 blade diaphragm which creates an attractive blur to the out of focus areas. This also creates smooth, rounded out of focus highlights when taking photos which have a strong light source in the background such as lights shining on the surface of water.

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

MTF Chart

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

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

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).