Digital Camera World » Sigma lenses

Sigma 18-35mm f/1.8: first-ever zoom lens with f/1.8 constant aperture unveiled

jmeyer — Thu, 18 Apr 2013 10:22:54 +0000

The Sigma 18-35mm f/1.8 DC HSM announced today is the first ever zoom lens to achieve a wide constant aperture of f/1.8 throughout the zoom range. Find out all the key specs of this new Sigma lens.

A Sigma 18-35mm f/1.8 price and release date were not available at the time of writing.

Sigma has revealed a new 18-35mm zoom lens with a constant aperture of f/1.8.

The new Sigma 18-35mm f/1.8 DC HSM is the first ever zoom lens to achieve a maximum aperture of f/1.8 throughout the zoom range, according to Sigma.

The previous widest aperture a zoom lens has been able to achieve throughout the zoom range has been f/2.8.

Designed for DSLRs with APS-C size sensors, the Sigma 18-35mm f/1.8 offers a focal range equivalent to 27-52.5mm in 35mm format.

Sigma says the new 18-35mm lens has been designed as a standard lens which is capable of shooting landscapes, portraits, still life photography, even studio photography.

The faster aperture throughout the zoom range will eliminate the need for photographers to keep fixed focal length lenses in their camera bags for brighter images, Sigma says.

The new Sigma 18-35mm lens also incorporates a wide glass-moulded aspheric lens and Special Low Dispersion glass, the latter which compensates for various aberrations as well as field curvature at the widest angle.

The Sigma 18-35mm f/1.8 also features Super Multi-Layer Coating to reduce flare and ghosting, and boost contrast, while a supplied petal type hood provides extra protection.

A Hyper Sonic Motor provides a silent AF function, Sigma says, while the 18-35mm f/1.8 offers a minimum focusing distance of 28cm and a maximum magnification ratio of 1:4.3.

Other features include a 9-blade rounded diaphragm, brass bayonet mount and a newly developed USB Dock that plugs into your computer and attaches to your lens, allowing you to update the lens firmware and adjust parameters such as focus.

Sigma 18-35mm f/1.8 Key Specifications

Sigma unveils ultra-light 18-250mm macro zoom for travel photography

jmeyer — Fri, 15 Jun 2012 10:21:34 +0000

Independent lens maker Sigma has announced a new DSLR zoom lens designed for travellers and backpackers, or anyone who wants an all-purpose zoom lens that’s both light and small.

The Sigma 18-250mm f/3.5-6.3 DC Macro OS HSM is different because it’s been manufactured using a special polycarbonate material called Thermally Stable Composite (TSC).

According to Sigma, TSC enables lenses to be both smaller and lighter. The virtual elimination of internal and external barrel expansion has enabled Sigma to design a lens that’s both smaller and lighter.

For example, the non-macro 18-250mm lens without TSC weighs in at 623g, whereas the new TSC macro version tips the scales at just 470g. Physically the lens is about 1.3cm shorter and about 0.5cm smaller in diameter, and has a filter thread of just 62mm.

This new walkabout lens is designed for DSLR cameras using APS-C/DX-size sensors, and offers a 35mm equivalent focal length of 28-400mm.

Sigma’s optical stabilisation (OS) technology is also included, which should mean sharper handheld shots at lower shutter speeds. The magnification ratio of the macro function is 1:2.9 and all 13 elements that make up the lens are multi-coated to reduce flare and ghosting.

For quieter and faster autofocusing, Sigma has incorporated its Hyper Sonic Motor (HSM) mechanism, which makes it ideal for newer budget DSLRs from Nikon that don’t have focus motors built into the camera body. There’s also a rounded, seven-blade diaphragm that should produce images with a softer and more pleasing bokeh.

The new lens will be available in Sigma, Sony, Nikon, Canon and Pentax mounts, but the first to market will be the Canon version, which is expected to launch in July 2012. Pricing and the availability for other mounts have yet to be announced.

DO or Di? Your lens markings explained

jmeyer — Mon, 02 Apr 2012 13:58:33 +0000

Does your lens has more letters after its name than a retired rocket scientist. What do all these lens markings mean?

You can refer to a lens simply by the name of the manufacturer, the focal length, and its maximum aperture – a Sigma 70-300mm f/4-5.6, say, or Canon 50mm f/1.4. But as lenses have often evolved from decades of development, they usually have a line of additional letters after their names, stamped on the barrel or printed on the boxes.

Some lens markings are about manufacturer branding – defining a more recent range, or a lens that’s built to higher standards than another. Others are to do with the optics themselves, and to highlight specific technologies used in the lens construction.

In the jargon-busting guide below, we’ll translate these lens markings for you.

The ultimate guide to understanding lens markings

AF Stands for autofocus. Nearly all lenses have this feature,  but there’s an increasing trend for niche lens manufacturers (such as Samyang and Carl Zeiss) to offer lenses that can only be focused manually.

AF-S Stands for autofocus-silent. This features on Nikon lenses that use a silent motor to control the autofocus.

AL Stands for aspherical lens. All camera lenses are made up of a number of individual lenses or elements. Many of these elements are spherical – as if cut from a sphere. Aspherical elements are less rounded – and are used in some types of lenses to help minimise chromatic aberration.

APO Stands for apochromatic. This features on Sigma lenses that use super-low dispersion (SLD) lens elements to reduce chromatic aberration.

AS Stands for aspherical (see AL).

Asp Stands for aspherical (see AL).

AT-X Stands for Advance Technology Extra – the branding used on all current Tokina lenses.

D A type of Tokina lens that’s compatible with full-frame SLRs.

DA Stands for Digital Auto. This features on a range of Pentax lenses that (unlike some earlier ranges) don’t have a manual aperture ring. They have a ‘Quick Shift’ mechanism that enables you to override focus manually, even when the lens is switched to autofocus.

DA* Star by name, star by nature. The premium lens range from Pentax, which combines weatherproofing with the advantages of the DA range.

DC This features on the range of Sigma lenses that are designed specifically for use with crop factor SLRs, and which can’t be used with full-frame models.

DFA This features on the range of Pentax lenses that will work with full-frame 35mm film cameras, but which are also optimised for use on crop-factor digital SLRs.

DG This refers to the Sigma lens range that’s suitable for full-frame SLRs (but that can also be used on crop-factor models).

Di Tamron’s ‘Digitally Integrated’ lenses have a full-size image circle, so they are suitable for full-frame and crop-factor SLRs.

Di II Tamron’s second-generation Digitally Integrated lenses are designed for use on popular crop-factor SLRs, and are not suitable for full-frame models.

DO Diffractive Optics is used on a handful of Canon telephoto lenses – the technology allows these long lenses to be made smaller and lighter than equivalents using conventional optical designs.

DT Sony lens with a smaller image circle, designed for use on crop-sensor cameras.

DX Tokina’s and Nikon’s way of marking lenses that are only suitable for crop-factor – or APS-C – SLRs.

ED A lens featuring Extra-low Dispersion glass in one or more of its elements, to help correct chromatic aberration. This abbreviation is used by Nikon, Panasonic, Olympus and others.

EF Standing for Electro Focus. This is the name of the lens mount that Canon introduced  on its first autofocus SLRs back in 1987. EF lenses can be used  on all Canon SLRs.

EF-S Electro Focus Short back-focus lenses were introduced by Canon in 2003. They have a small image circle so they are only suitable for use on crop-factor SLRs. A modified mount means that they can’t physically be fitted onto incompatible (ie full frame) Canon models.

EX Sigma’s designation for its premium lens range.

f/X.X The f-stop number is  the size of the lens’s maximum aperture, measured as a fraction of the focal length of the lens. On some zoom lenses there may be two apertures quoted – f/4-5.6, for example. This means that the maximum aperture gets smaller as the lens is zoomed in. The maximum aperture on the lens barrel may also be expressed as  a ratio – so 1:4-5.6.

FA Pentax lens that’s full-frame compatible, and that features an old-fashioned aperture ring.

FO Tokina’s Focus-One-touch mechanism allows you to switch quickly from autofocus to manual focus operation, and back again, by snapping the focus ring backwards and forwards.

FX A Nikon, or Nikkor, lens that’s compatible with its full-frame SLRs, as well as crop-factor ones.

G Stands for Gold – a designation found on top-class Sony lenses. It’s also used for current Panasonic Lumix compact system cameras and lenses.

HID Stands for High Index Dispersion, a type of glass used in Tamron lenses that helps to minimise chromatic aberration.

HSM Sigma’s Hyper Sonic Motor is used in some of its lenses to provide faster and quieter autofocus operation.

IF Stands for Internal Focusing, and is found on many lenses from many manufacturers. The lens is constructed so that it doesn’t change in length as the lens is focused. It also means that the front element doesn’t rotate – which can help with the use of some lens attachments, such as petal-shaped lens hoods and polarising filters.

iFn Stands for i-Function, a feature of Samsung NX cameras which allows photographers to access a number of key camera settings via a button and ring around the lens.

II This stands for second-generation – a classic lens that’s been updated in design by the original manufacturer.

III Stands for third-generation.

IS Stands for Image Stabilization – optical camera shake reduction found in a wide number of Canon lenses.

L Stands for Luxury, and is used to designate Canon’s best pro lenses, which have superior build quality and weatherproofing.

LD This features on Tamron lenses that use one or more Low Dispersion lens elements to help reduce chromatic aberration.
mm Stands for millimetres – used to measure the focal length of a lens.

OIS Optical Image Stabilisation – the system used on Panasonic lenses to reduce camera shake.

OS Optical Stabilization is  the system used on some Sigma lenses to reduce camera shake.

PC-E Stands for Perspective Control-Electronic. Used to designate Nikon’s range of tilt-shift lenses, which enable you to move the front elements on the lens to avoid or exaggerate lens distortion. They are commonly used in architectural photography to ensure vertical lines remain parallel in the picture.

PZ Stands for Power Zoom,  a servo-assisted zoom facility found on some Panasonic compact system camera lenses.

PZD Stands for Piezo Drive,  a type of ultrasonic motor used in Tamron lenses to provide  fast, quiet autofocus.

RF With Rear Focus, the group of elements nearest the camera are used to focus, providing faster autofocus. This feature is found on super telephoto lenses.

SAM Stands for Smooth Autofocus Motor – used in recent Sony Alpha lenses.

SD Super-low dispersion –  the glass used in Tokina lenses  to reduce chromatic aberration.

SDM Supersonic Drive Motor, Pentax’s fast, quiet focus motor.

SLD Super-low dispersion – lens elements in Sigma lenses that reduce chromatic aberration.

smc Stands for Super Multi Coating, a seven-layer coating used on Pentax lenses to reduce light reflected the lens itself.

SP Super Performance – a long-standing tag found on top-of-the-range Tamron lenses.

SSM Supersonic motor – used for high-speed autofocus in top-of-the-range Sony lenses.

SWM Silent Wave Motor,  the high-speed quiet AF motor used on Nikon’s AF-S lenses.

TS-E Tilt-shift Electronic – Canon’s range of perspective control lenses (see PC-E).

UD Ultralow dispersion – type of glass used in Canon lenses to reduce chromatic aberration.

USD Ultrasonic Silent Drive, Tamron’s fast, quiet AF motor.

USM Ultrasonic motor – fast, low-noise autofocus motor used by some Canon lenses.

VC Vibration Compensation – optical camera-shake reduction system on some Tamron lenses.

VR Vibration Reduction, Nikon’s image-stabilisation system.

WR Weather Resistant – found on certain Pentax lenses.

XLD Extra Low Dispersion; glass used in some Tamron lenses to reduce chromatic aberration.

XR Extra Refractive – type of glass used in Tamron lenses. It can bend light at bigger angles than normal glass, helping make the overall size of a lens smaller.

ZA Zeiss Alpha – a range of Sony lenses made by Carl Zeiss.

Sigma 10-20mm f/4-5.6 EX DC HSM Lens review

dcworld — Tue, 13 Oct 2009 12:37:31 +0000

An ultra-wide angle lens at a cheap price, but will it deliver?

The Sigma 10-20mm f/4-5.6 is the cheapest lens in the group. The respectable 10-20mm zoom range is equivalent to 15-30mm on 1.5x crop factor cameras like Nikon and Pentax, and 16-32mm on a Canon body.

It’s available in all the same mounts as Sigma’s new, constant-aperture version of the lens, as well as in Olympus Four Thirds mount (although the effective zoom range of 20-40mm is less impressive at the ultra-wide end on Olympus cameras).

The Hypersonic Motor (HSM) autofocus system isn’t blindingly fast but proved highly accurate and whisper-quiet in our tests. The lens is also very smartly turned out, belying its modest price and featuring the texture black finish favoured by Sigma’s EX series lenses. As with other Sigma lenses, it comes complete with dedicated hood and a high-quality carrying pouch that’s worth having.

The two ELD elements of the newer Sigma 10-20mm lens on test are missing from the older version. The line-up is instead built around three SLD elements and three aspherican elements. On paper, this looks inferior but, in our tests, the lens performed as well as Sigma’s more expensive counterpart and, although sharpness was a lacking when shooting wide open, the optics sharpened up nicely at f/8.

Sigma 10-20mm f/3.5 EX DC HSM

dcworld — Tue, 13 Oct 2009 12:27:48 +0000

We put one of Sigma’s ultra-wide angle lenses through its paces.

Sigma’s newest 10-20mm lens is bigger and heavier than the other Sigma model, also tested here. It features a larger front elements that requires an 82mm filter thread, whereas most lenses in the group only need 77mm filters.

Both Sigma lenses use the company’s HyperSonic Motor (HSM) autofocus, which is practically as quiet as the equivalent Canon and Nikon systems, although it proved rather slower in our tests. Full-time manual focus override is available in all the lens’s mount options, which include Canon, Nikon, Pentax, Sigma and Sony.

The biggest bonus of the new Sigma 10-20mm lens is that it has a constant maximum aperture of f/3.5 throughout the zoom range. This is very slightly faster at 10mm and just over a stop faster at 20mm. For our money, however, this alone doesn’t warrant the additional £210 cost over Sigma’s other model, as overall image quality didn’t prove noticeably better.

There’s quite a feast of glassware inside the new Sigma 10-20mm lebs, including one Special Low Dispersion (SLD), two Extraordinary Low Dispersions (ELD) and four aspherical elements. There are also Super Multi-Layer lens coatings to reduce ghosting and flare but, overall the Sigma lacked sharpness when shooting wide open, making its reasonably fast constant aperture less of an attraction in practical terms.