A True Fixed-Focal Length Lens for a D-SLR Camera

Fixed focal-length lenses are a rare find in the digital arena. Most abundant are the zoom lenses; and, usually none that offer a larger aperture for low-light shooting as well as providing a nice out-of-focus background to allow the primary subject to stand out. Sigma probably thought of these important characteristics when they developed this unique wide-angle lens.

By definition, at least in 35mm film photography, the full-framed wide-angle lenses are in the range 35mm-24mm. Ultra-wide starts below 24mm; most popular are 20mm, 18mm and 17mm, with the rectilinear 14mm and 12mm pushing the envelope of ultra wide. This places Sigma 30mm f/1.4 near the middle of the wide-angle range compared to the standard 50mm focal length.

Sigma 30mm f/1.4 EX DC HSM AF

Sigma 30mm f/1.4 EX DC HSM AF is quite an impressive prime lens that provides a true focal length on a digital SLR (D-SLR) camera. This is the EX lens, meaning that it is the top-of-the-line Sigma lens which stands for superior build and optical quality. Its gold coated ring also helps make that distinction. The DC denotes the exclusive operation on digital SLR cameras, because the lens incorporates optical (image) circle that matches the smaller size of the D-SLR cameras compared to the standard 35mm film. In other words, the optical properties of this lens are a true match for D-SLR cameras. Being among the top-of-the-line lens, Sigma 30mm f/1.4 EX DC HSM AF features an HSM that provides a silent and swift auto-focus operation.

The lens itself is quite compact (as does any short-focal length lens). However, it is not light by comparison, even though it weighs a little less than a pound (15.2 ounces). Its weight suggests its well structured and sturdy construction with an impressive appearance, a high-quality gem indeed. Its wide rubber ribbed focusing ring is equally appreciative that provides an excellent grip and smooth operation. The front barrel accepts a 62mm filter ring. This abnormally large filter ring is due to its impressive large aperture at f/1.4 (compared to those with f/2.8 or f/2).

In terms of optics, this lens has everything to help it achieve image definition of high quality. Containing 7 elements in individual group, the Sigma 30mm f/1.4 features Aspherical lens at the rear to help eliminate (or reduce) color separation, known as chromatic aberration. The SLD (Special Low Dispersion) glass near the front helps to ensure the control of this color alignment to yield sharp images and superb color and contrast.

The Sigma 30mm f/1.4 EX DC HSM AF features a gearless HSM motor that enables a focus over-ride in auto-focus mode at any time during auto-focusing. The result is quiet, smooth and instant. The lens provides an impressive close focusing distance of 40cm, an equivalent of 15.7 inches.

The Retail Package

The retail package includes

- Sigma 30mm f/1.4 EX DC HSM AF (Nikon)
- Lenshood
- Soft pouch
- Instruction/Information/Registration sheet

Mount/Availability/DSLR Format

Sigma 30mm f/1.4 EX DC HSM AF is available in Sigma, Canon, Minolta, Nikon-D and Pentax, as well as Sony. It is important to mention that this lens is not compatible with standard 35mm film camera.

Since this lens is offered in a number of mounts for various brand D-SLR cameras listed above, I would like to stress that my review here is based on D-SLR camera in Nikon mount, particularly Nikon D1X and D70s.

Field Test and Practical Usage

The Sigma 30mm f/1.4 EX DC HSM balances quite nicely with Nikon D70s. With its tulip shaped (die-petal) hood attached, the whole set is physically quite appealing. Its auto-focus is swift and silent. Manual over ride can be achieved by rotating the focus ring, which is quite smooth and well dampened. There is a window distance scale to provide focus information during shooting.

My primary job for this lens is indoor photography, particularly wedding. Therefore, I mostly require to shoot this lens with its wide aperture, in the range f/1.4-f/4. Its 15.7-inch close focusing distance is an excellent asset for placing the primary subject in the foreground. Its wide aperture f/1.4 or f/2 enables me to control the depth of field, that is, I can make the background extremely out of focus so I can draw full attention to my subject. Because of its wide aperture, I can shoot handheld without requiring the use of a tripod, which is quite clumsy and interfering with my spontaneous candid portraits.

In terms of optical quality, this lens produces impressive picture definition: excellent sharpness, great color fidelity and admirable contrast. As I normally do with any lens before I commit to its serious services, I put the Sigma 30mm f/1.4 EX DC HSM AF to a standard test for sharpness relative to aperture range and distances, even though I know that I will mostly shoot with it using a wider aperture in the range f/1.4 - f/4 or f/5.6.

For a fixed focal-length lens, it is very easy to test for its sharpness relative to aperture and distance, especially on a digital SLR camera where image quality can be judged almost instantly. I set my camera for the smallest (slowest) ISO speed for fine resolution, with a tripod to help maintain stability to eliminate any blur that might have occurred due to camera shake.

In terms of optical resolution, sharpness is very consistent throughout its aperture range, except f/16. At f/1.4 (wide open), the lens exhibits quite noticeable light falloff; sharpness is quite good around the center but becomes soft spreading out to the edges. Overall contrast is quite excellent. Stopping down to f/2.0, light falloff weakens a bit but is still noticeable; however, sharpness from the outer-center to the edges improves drastically. By f/4, no light falloff is seen; and the lens maintains its image sharpness throughout the image plane. Sharpness continued all the way to f/8 and f/11 but dropped abruptly at f/16. The nice thing was that image contrast was consistent throughout the aperture range. From my test images, I would say the lens produces its optimum performance at f/4; but the distinction was only on images toward the edges. Center sharpness was very consistent throughout its aperture range f/1.4 through f/11.

There is a small barrel distortion seen on this lens, which can only be visible on images containing straight-line elements along the edges of the frame. For landscape or people photography, I can barely detect it at all. Flare is very well controlled throughout the aperture range; it helps to shoot this lens with its hood on. It only shows some ghosting when a bright object appears in the frame at a certain angle.

In addition to using this lens for people photography, I have tested for landscape images. It delivered equally impressive sharpness and excellent contrast. But, frankly, I would not buy this lens for landscape photography, where images are required to be extremely sharp throughout the depth-of-field range, meaning that the lens must be stopped down significantly. However, this lens can only be stopped down to f/16 compared to those in the "regular" f/2.8 that can yield all the way to f/22 or even f/32. The overall image quality at f/16 is not the greatest strength in this lens. While it is still sharp at f/16, I would rather use my 17-35mm f/2.8 zoom instead, because of its consistent sharpness at smaller aperture. In other words, the Sigma 30mm f/1.4 is not really a good lens to shoot at f/16. Its advantage lies in its wider f-stops at f/1.4 or f/2 and not f/16.

Image Quality -- A Closer Look
As anticipated, this lens delivered outstanding out-of-focus backgrounds allowing the subject to stand out -- thanks to its 8 blade diaphragm. I regularly use this lens for people photography shooting at f/1.4 and f/2 to achieve such impressive results. Its swift HSM operation on auto-focus is equally impressive which enables me to capture images of people in their natural expressions.

Conclusion

A combination of true 30mm focal length, formidable image quality at wide open, sturdy construction makes it the only short focal-length lens available for digital SLR cameras. In addition to this, its close focusing distance is quite advantageous which allows the capture of images up close, especially in a tight area or crowded people.

I love its pleasing out-of-focus effects at wide open. The lens delivers excellent images, even at wide open and quite consistent throughout. Because of its large aperture, it is an excellent lens for low-light photography without resorting to using flash or a tripod. The use of the popular 62mm filter size is a welcome design, compared to 55m or 67mm. A number of my lenses use 62mm filter, and thus the addition of this lens does not require the purchase of a new set of filters.

The reasonably high price of this lens reflects that fact that it is an extremely fast wide-angle lens; and it should be photographed using those wide aperture settings. Unfortunately, it is not a lens meant for all practical purposes without some sacrifices, especially since it can only be stopped down to f/16; and its performance at that setting is not that great either. Another drawback I see is that it is only available for digital SLR cameras.

***********
Specifications: Sigma 30mm f/1.4 EX DC HSM AF

Lens Construction (Groups/Elements): 7/7
Angle of View: 45 deg.
Diaphragm Blade Number: 8
Maximum Aperture: F/1.4-16
Minimum Focus: 40cm (15.7 inches)
Filter Diameter: 62mm
Weight: 430g (15.2oz.)
Diameter x Length: 3.05in x 2.30in)
Accessory: die-petal (tulip-shaped) lens hood
Mount: Canon, Minolta, Nikon-D, Pentax