| 8–16mm f/4.5–5.6 DC HSM | |
| Maker: | Sigma |
| Feat-Is: | n |
| Focusdrive: | Ultrasonic motor |
| Feat-Macro: | n |
| Application: | Consumer Super Wide-Angle Zoom for Digital SLRs |
| Flength: | 8–16 mm |
| Aperture: | f/4.5/22 – f/5.6/29 |
| Groups: | 11 |
| Elements: | 15 |
| Diaphragm: | 7 |
| Close-Dist: | 24 cm (9.4 in) |
| Max-Mag: | 1:7.8 |
| Weight: | 555 g (16.4 oz) |
| Max-Diameter: | 75 mm |
| Max-Length: | 106 mm |
| Filter: | NA |
| Hood: | y |
| Av-Diag: | 114.5° – 75.7° |
| Start: | February 2010 |
| Msrp: | $1100 USD |
| Stop: | February 2020 |
The Sigma 8–16mm lens is an enthusiast-level, ultra wide-angle rectilinear zoom lens made by Sigma Corporation specifically for use with APS-C small format digital SLRs. It is the first ultrawide rectilinear (non-fisheye lens) zoom lens with a minimum focal length of 8 mm, designed specifically for APS-C size image sensors.[1] The lens was introduced at the February 2010 Photo Marketing Association International Convention and Trade Show.[2] At its release it was the widest viewing angle focal length available commercially for APS-C cameras.[3] It is part of Sigma's DC (Digital Camera) line of lenses, meaning it was designed to have an image circle tailored to work with APS-C format cameras.[3] The lens has a constant length regardless of optical zoom and focus with inner lens tube elements responding to these parameters.[4] The lens has hypersonic zoom autofocus.
The lens is sold in versions that fit the bayonet mounts of Nikon, Canon, Sigma, Sony/Minolta and Pentax APS-C cameras. The lens has been discontinued by Sigma Corporation in 2020.[5]
The lens measures 106mm75mm and weighs 555g. It has a bulb-like aspherical lens, similar to notable wide-angle and fisheye lenses such as the Nikon AF-S NIKKOR 14-24mm f/2.8G ED, Nikon AF DX Fisheye-Nikkor 10.5mm f/2.8G ED, or Tokina AT-X 107 DX AF 10-17mm f/3.5-4.5 fisheye lens. Because of the shape of front element, it is not compatible with many filters, including UV filters, but the frontal exposure is rectified by a petal-shaped lens hood element.[4] Because the lens has a permanent lens hood affixed, it comes with a friction-fit aluminum element, variously described as a sleeve, ring or shroud, that surrounds the hood to enable the placement of a front cap on the lens.[4] PC Magazine Jim Fisher says the lens is relatively large and heavy;[6] A reviewer at photozone.de says that for a wide-angle lens the dimensions are unusually narrow but long.[4]
The sleeve is threaded, making it compatible with 72mm filters, but vignetting is severe with the sleeve in place.[3] The construction is plastic although the lens' rear mount is metal. The distance meter is recessed inside a window, but no depth of field meter or infrared index is present. The 7/8" zoom ring is made of raised rubber ridges and operates over a 75 degree turning radius. The focus ring is similarly constructed with more closely spaced ridges and a 100 degrees of turning action. The ridges of both rings are parallel to the lens.
The only physical controls on the lens are the AF/MF toggle switch and the two rings, controlling the zoom and focus.[6] The lens does not have image stabilization. This is common for wide-angle photography which can be performed well using hand-held techniques.[7] Over the range of focal lengths, the minimum and maximum aperture vary.[8]
The lens features a hypersonic zoom motor for its autofocus, which is considered to be a fast and quiet design.[4] [7] In addition, manual override is allowed in the single-shot autofocus mode.[4] The lens, which focuses internally, has one of the lowest maximum magnification measurements in its class (which includes the Canon 10–18mm and 10–22mm, Sigma 10–20mm f/3.5 and Sigma 10–20mm f/4–5.6 EX DC HSM, Tamron 10–24mm f/3.5–4.5 DI II, Nikon 10–24mm f/3.5–4.5G ED AF-S DX, and Tokina 11–16mm f/2.8 AT-X Pro DX lenses).[8] [3] The lens' autofocus feature is not functional with Pentax ist* series and K100D DSLR cameras that do not support hypersonic zoom mechanics.[1] The lens is capable of focusing from infinity to minimum focusing distance and back in under a second: so micro focusing is rapid.[8] However, because of the narrow focus range (0.13x) the lens is not suitable for macro photography.[8]
The lens exhibits significant distortion in keeping with the problems of wide-angle lenses.[4] The complex barrel distortion is approximately 2.9% at 8 mm focal length but is fairly insignificant as the focal length is raised above 12 mm, according to Photozone.de.[4] PC Magazine reports 3.1% distortion at 8 mm and 0.7% at 12 mm.[6] It also reports that distortion switches to pincushion distortion of 1.4% at 16 mm.[6] SLAR Gear reports that the point of convergence between barrel and pincushion is about 13 mm.[8] Foreground subjects seem abnormally large compared to similar background subjects with this lens.[3]
By combining the wide angle focal lengths with narrow apertures, the lens provides strong depth of field rather than making blurred backgrounds.[3] The lens is constructed with a hybrid aspherical lens that when combined with two glass mold elements provides excellent correction for distortion as well as astigmatism.[1]
As all lens systems, natural vignetting (gradual reduction of an image's brightness from the center towards the periphery) is present due to Lambert's cosine law – this becomes more pronounced at shorter focal lengths.[4] Wide open at 8 mm, about 0.75 EVs of shading are apparent at the corners, while at 16 mm only about 0.25 EV of shading is noticeable when comparing the corners to the center.[8] For most of the focal length range of the lens, there is between a half stop and third stop of corner shading.[8] Alternatively, stopping down to higher f-numbers lessens vignetting.[9]
The lens is equipped with a full-frame digital SLR-compatible mount allowing the usage of both APS-C sized cameras and formats larger than APS-C – the built in lens hood however visibly restricts the field of view (FOV) on formats larger than APS-C – see example above.[1] [8] The FOV in APS-C sized cameras is further restricted at shorter focal lengths if the front cap adaptor ring is not removed – see example below.[4]
The lens' modulation transfer function (MTF) metrics for its image resolution (sharpness) were described as "surprisingly impressive...throughout the entire zoom range" by Photozone.de.[4] The sharpness, in terms of line widths per picture height (LW/PH), is most uniform at 8 mm (especially near the f-number of 8 where it is even throughout the image) with strong numbers at the center, borders and corner. Higher focal lengths were less impressive.[4] Optical tests were consistent with lab results pointing to excellent sharpness.[10] However, exposure testing seems to belie the stated f-number capabilities of the lens, since stopping down from widest aperture did not change results, according to Gietler.[10]
At its widest aperture, the sharpness does not meet the 1800 threshold at either 8 mm (1572, f/4.5) or 12 mm (1356, f/5), but at 16 mm (f/5.6) it achieves over 2000 lines per picture height. However, stopping down improves the sharpness at all focal lengths, according to PC Magazine. At 8 mm, 1800 is reached at f/8, while at 12 mm it is still only at 1509 by f/8.[6] The image quality is asymmetric with better performance on the right side.[3] At 8 mm and f/4.5, it has 1 blur unit in the center and 1.5 in the corners.[8] Although the images are slightly sharper at f/5.6, SLR Gear claims sharpness declines significantly at f/11 to almost 2 blur units with further stopping down increasing blur to 3.5 at f/22.[8] At the longer focal lengths for this lens, stopping down to f/29 yields a 5 blur unit result.[8]
The lens is the first that incorporated Sigma's FLD glass elements, designed to correct color aberrations like fluoride glass does.[4] Chromatic aberrations are indeed superior to earlier Sigma wide-angle lenses. In fact, although they might be noticeable at 100% image magnification, they are not at the magnifications now common with prints relative to the number of megapixels that images are commonly captured at.[4] According to Sigma's website, Super Multi-Layer Coating reduces flare and ghosting.[1] As one zooms out with this lens chromatic aberration becomes significant at the corners.[8]
The aperture stop-down focal lengths make the lens a laggard among wide-angle lenses.[3] Thus, it is not strong at gathering light for stop action photography. However, DSLR cameras have improved at higher ISO settings.[3] However, wide-angle photography (below 16mm) continues to need stronger lighting than is possible by built in flashes if trying to make up for low light situations.[3]
At 8 mm and 16 mm, respectively, the lens is able to focus on an area 12.25inches and 7inches in width.[7] Although the official close focus distance is 24cm (09inches),[1] Scott Gietler reported that by using the spot-focus mode, rather than multiple focus points, he was able to achieve a 3inches minimum working distance (glass to subject).[7]
The lens is useful for deliberative shots by landscape photographers and other skilled artists.[6] The challenge of the vast field of view may be overcome by some casual users.[6] Car photographers benefit from the new perspective of this lens.[3] The lens was a 2010 American Photo Editor's Choice.[1]