Review Sigma 14mm f/1.8 Art + MC11 @ Sony A7R mk2
The Sigma 14mm F1.8 DG HSM Art is not only the world-record holder with f/1.8 for 14mm on full frame, Sigma also proudly reports that this dust- and splashwater-tight lens is suitable for future sensors with more than 50 megapixels. The lens is available with a Sigma, Canon or Nikon mount. We tested the Sigma MC-11 on a Sony FE camera (Sony A7R II).
The Sigma 14mm f/1.8 Art is one of the few Art lenses that is sealed to weather resistance.
The solid construction of the Sigma Art lenses is well-known by now. Relative to previous Art lenses that we have reviewed, this lens is also extra well-sealed against dust and splashwater. For use under extreme conditions, that is a welcome addition. This lens is available with a Canon, Nikon or Sigma mount. The extremely solid brass mount shows no play at all when you attach this lens to your camera, in this case via the Sigma MC11 on a Sony A7r II. In the Nikon mount, the aperture is also controlled electromagnetically, like most of the modern Nikon E lenses.
practice shot Sigma 14mm f/13 Art @ f/1.8, 250 ISO, 1/60 sec.
Sigma 14mm f/1.8 ARt & AstroPHOTOGRAPHY
500 rule: longest shutter time in seconds without Star trail = 500 divided by the focal length
The Sigma 14mm f/1.8 Art, with its extremely roomy field of view, is ideal for creative documentary, architecture, landscape and astro photography. Astrophotographers dream for three reasons about a bright ultra-wide angle lens like the Sigma 14 mm f/1.8 Art.
First, you can capture a large part of the starry sky – including the Milky Way – with a short focal length, without having to compile the image from multiple shots.
Second, you can use a long shutter time (30 seconds), without the stars changing into stripes (“star trails”) as a result of the rotation of the earth.
Third, the combination of a long shutter time and extremely high brightness – f/1.8 is a world record for 14 mm – means a low ISO setting, which results in a better signal-to-noise ratio.
The video below from Jose Francisco Salgado on Vimeo is a beautiful illustration of the high image quality of the Sigma 14mm f/1.8 Art for Astrophotography.
If you would like to see more like that, then read his article Astrophotography with the Sigma 14mm f/1.8 Art lens on Dpreview.
BUILD AND autofocus
Focusing is fast (from infinity to 1.5 meters in 250 ms) and quiet. The newly designed HSM AF motor can always be manually overruled, if you want, without you first having to flip a switch on the camera or lens (AF/MF is the only switch on the Sigma 14mm f/1.8 Art).
VIGNETTING, FLARE AND DISTORTION
The picture above from Sigma shows that the vignetting at full aperture will already be clearly visible, decreases noticeably to f/4, and remains more or less constant after that. At full aperture, we measure 1.75 stops vignetting in uncorrected RAW files. That is already very good in itself for a wide-angle lens on a camera with a full-frame sensor, but at f/4, the vignetting had decreased to 1 stop.
If you open RAW files in Lightroom or Photoshop, automatic correction of vignetting is done in advance, so that you only see 1 stop vignetting at full aperture (and 0.4 stops at f/4). The same is true for jpg files that you save in the Sony A7R II.
Exposure and contrast of this practice shot are modified to more clearly show the ghosts as a result of flare. Sigma 14mm f/1.8 Art @ f/13, 100 ISO, 1/160 sec.
Practice shot Sigma 14mm f/1.8 Art @ f/1.8, 100 ISO, 1/2500 sec.
At the introduction, the manufacturer reported that this lens is suitable for cameras with sensors of 50 megapixels or more. In addition, various kinds of chromatic aberrations are minimized by using three SLD (special low dispersion) elements and four aspherical elements. This results according to Sigma in outstanding image quality into the corners. And that’s true. More or less.
Sigma indicates that this lens is designed for cameras with a sensor of 50 megapixels or more. The Sony A7R II comes pretty close with a 42-megapixel sensor without anti-aliasing filter. The center sharpness is indeed phenomenal. At full aperture, it is already good, and maximal at f/5.6, as it appears from our Imatest measurement results. But the sharpness in the corners lags visibly behind the center sharpness even on a camera with less than 50 megapixels at f/1.8 to f/5.6. If you look at color errors (lateral and longitudinal chromatic aberration), then those are remarkably absent across the whole frame. As far as that is concerned, Sigma has put up an exceptional performance.
Uncorrected RAW files show a distortion of 3% barrel-shaped in our Imatest measurements. Because jpg files and RAW files that you open in Photoshop or Lightroom are automatically corrected, you see just 1.5% of it in practice. To illustrate, the picture that Sigma America shows with the product specifications as "effective distortion."
You usually do not buy a wide-angle lens for the bokeh. Even so, the combination of a camera with a full-frame sensor, f/1.8 and 9 rounded aperture lamellae is the best recipe for a beautiful background blur with a 14mm lens. The closer you creep up to your subject, the better that works.
ConclusiON: REVIEW Sigma 14mm f/1.8 Art + MC11 @ Sony A7R mk2
WYSIWYG score: This table shows the performance of this lens if you save the files in the camera as jpg, where you have applied all available in-camera lens corrections. This score gives you for this lens/test camera combination: "What you see is what you get".
Pure RAW score: This table shows the performance of this lens if the file is stored in the camera in RAW format. This score approaches the intrinsic quality of the combination of lens and test camera. If you use lens correction profiles in Photoshop or Lightroom for converting RAW files, then the RAW scores for distortion, vignetting and chromatic aberration are even better.