18-250mm f/3.5-6.3 DC Macro OS HSM
Produced in their legendary Aizu facility in Japan, Sigma presents their 18-250mm f/3.5-6.3 DC Macro OS HSM zoom lens. Building on 50 years of innovation in precision optics design and craftsmanship, the 18-250mm is a versatile super zoom lens and direct successor to the widely acclaimed Sigma 18-250mm F3.5-6.3 DC OS HSM. Evolving from the success of its predecessor, the 18-250mm sets a new generation’s high zoom ratio by achieving improved image quality, a significantly reduced size and an advanced close focus capability. With its ability to cover such an extreme range of focal lengths, this lens makes a great all-round offering to any budding photographer.
By using the innovative Thermally Stable Composite material, the 18-250mm is 25% lighter than its predecessor Click here to view larger
The Lens Design
Design features make up the foundation of the Sigma 18-250mm lens. Measuring 7.4cm x 8.7cm and weighing just 470g, the 18-250mm is both more compact and 25% lighter than its predecessor. Sigma have achieved this incredible weight reduction by using a new lighter material called Thermally Stable Composite (TSC) instead of much heavier Polycarbonate. This innovative material has a thermal shrinkage level equivalent to aluminium and has little contractility, even when subjected to sharp temperature changes.
The 18-250mm features Sigma’s dedicated Optical Stabiliser system (OS). The system offers an effective blur correction of 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. Working alongside the OS is 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 petal design hood (included) 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. All the above features combined give the lens an extraordinary ability to produce in focus images whether at close or long ranges.
The final design feature on the 18-250mm lens is a greatly improved bayonet mount. Sigma manufacture the mount from speciality treated brass, the result of which create a more solid and rust resistant connection between camera and lens.
From Macro to Telephoto
By covering such a broad range of focal lengths, the 18-250mm lens is capable of taking many different types of images and therefore accommodating many different types of user. With a fixed minimum focusing distance of 35cm throughout the entire focal range and a maximum reproduction ratio of 1:2.9, the lens performs well at taking close up images regardless of the distance between subject and lens. At the lower focal length settings (18-30mm) the lens acts like a Macro and reproduces detailed wide angled images of close up subjects. Then simply zoom in a little and the lens automatically turns into a standard-medium range telephoto. Finally, increase the zoom to the maximum focal lengths and it becomes a full telephoto lens allowing you to pin point a specific area within a landscape or scene and reproduce it in stunning close up detail. Higher F stop numbers as well as OS technology enhance the performance of the lens for long distance photography.
One SLD and three aspherical lens elements counter various optical aberrations and increase light transfer to the sensor Click here to view larger
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 18-250mm incorporates a set of cutting edge and unique optical features which work to create bright and sharp images, at all focal lengths. One out of a total sixteen lens elements, is manufactured from Special Low Dispersion (SLD) glass, renowned for its high resolution and light transmission properties. It works in conjunction with three aspherical lens elements (one double sided) to counter various colour and optical aberrations throughout the zoom range. The configuration also ensures that all levels of distortion are corrected. The resulting images speak for themselves in terms of sharpness and resolution.
The lens incorporates a 7 blade diaphragm which produces 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......
Packing so many focal lengths and optimising features, the Sigma 18-250mm replaces the need to carry several lenses making it the ultimate “all in one” DSLR lens. The compact size, 25% weight reduction and a zoom lock function, make the lens extremely portable and ideally suited to travel as well as general day use. With ability to instantly switch from a telephoto to macro lens and assisted by various features, it is suited to a wide range of specific uses from close-up wildlife photography, landscapes as well as long distance pursuits. The OS system and HSM also ensure that the lens performs well when composing handheld shots both near and far. If you are tired of carrying around and continuously interchanging your lenses to get the right shot, then the Sigma 18-250mm is a perfect all round solution for you.