105mm f/2.8 EX DG OS HSM
Produced in their legendary Aizu facility in Japan, Sigma presents their 105mm f/2.8 EX DG OS HSM prime lens. Building on 50 years of innovation in precision optics design and craftsmanship, the 105mm is a mid telephoto macro lens and direct successor to the widely acclaimed Sigma APO Macro 105mm F2.8 EX DG lens. Building on the success of its predecessor, the 105mm encompasses several advanced optical and design features which help to reduce various aberrations and loss of focus. Deep, clear and sharp images are produced as a result, making this lens a great value mid power offering to any budding photographer.
The Lens Design
Design features make up the foundation of the Sigma 105mm lens. The most prominent feature is Sigma’s dedicated Optical Stabiliser system which is new to this model. The system offers an effective blur correction over 4 stops, helping to stabilise the image and counter shake. It is also linked to the viewfinder, allowing for more accurate previews and thus in focus images. The lens features Sigma’s in-house developed inner focussing system, which both eliminates the need to extend the barrel, reducing light loss, and the need to rotate the front lens. In staying fixed, the front lens can accommodate a hood (used in conjunction with the supplied hood adapter) that helps to counter light related issues such as glare. The inner focussing system also allows for the use of Circular Polarising filters. The lens also features Sigma’s exclusive Hyper Sonic Motor (HSM) which works to auto focus images in a fast, accurate and silent manner. Combined with the Optical Stabiliser system, the lens has an extraordinarily efficient focus over long distances. The lens is manufactured to Sigma’s high standards with a splash proof body constructed from strong but lightweight polycarbonate, layered in a hard-wear paint finish.
The Sigma 105mm is a true macro lens, capable of capturing an object on its sensor at the exact same size as the object exists. This 1:1 magnification capability gives the lens an unrivalled ability to create scaled and realistic images. With an F-stop of 2.8, the lens is still capable of auto-focusing at a 1:1 magnification, very useful considering the often close-up style of photography that this type of lens is used for. Also when close-up, the 105mm focal length allows a user to increase the working distance between them and a subject giving the added benefit of reducing unwanted shadow formation in the composition.
The Optical Composition
In all forms of lens construction, Sigma puts the highest emphasis on the quality and craftsmanship of the internal optics. As a result, the 105mm incorporates a set of cutting edge and unique optical features which work to create bright and sharp images, even at extreme close-up perspectives. Two out of sixteen lens elements are manufactured from Special Low Dispersion (SLD) glass, renowned for its high resolution and light transmission properties. The SLD glass helps to counter various spherical and optical aberrations which are commonly found in macro lenses, such as chromatic aberration. The SLD elements also reduce field curvature and ensure high rendering performance at all shooting distances.
The lens incorporates a 9 blade diaphragm which constructs a desirable blur (bokeh) effect on out of focus areas. The diaphragm also smoothes out intense back lighting, making them appear as rounded highlights as opposed to areas of over exposure. This effect helps to over emphasise the foreground subjects and smooth out the background, creating a well balanced image. Finally, Sigma applies Super Multi Layer coatings to all lens elements, which work to create an optimum colour balance by reducing the damaging effects of ghost and flare. The coatings also help to maximise light transmission to the DSLR’s sensor.
A Lens Most Applicable For......
With a medium focal length of 105mm and macro 1:1 magnification, this Sigma lens is a perfect match for any photographer who would like to compose close-up or portrait images. Quick and accurate auto focussing combined with a dedicated Optical Stabiliser, mean that close-up and handheld images can be composed with accuracy and ease. The greater working distance accommodated by the 105mm focal length and the silent nature of the HSM, also make the lens ideal for taking close-up images of insects and other wildlife, subjects that by nature are easily scared off. The superior splash proof design helps protect the lens outdoors, when in pursuit of such nature. Finally, the first class optics allow for close-up subjects to be displayed in stunning clarity, opening up a previously unattainable world for photographers.
A range of separately available Sigma APO teleconverters can be used in conjunction. The converters substantially increase the focal length of the lens and in doing so allow users to increase their working distance from a subject while still maintaining a 1:1 macro magnification.