Recently, Sigma announced the addition of a new member of the "I" series of lenses - 20mm F2 DG DN, as the current "I" series of lenses in the widest field of view, the largest aperture lens, the launch of 20mm F2 DG DN shows that Sigma has found the most suitable balance between volume and performance, through the use of this period, we also want to talk to you about the unique charm of this ultra-wide angle lens.
Exterior design
Let's take a look at the basic information of this lens first:
Lens construction: 13 elements in 11 groups
Closest shooting distance: 0.22m
Maximum shooting magnification: 1:6.7
Filter size: 62mm
Overall size: 70∅ × 72.4mm
Weight: 370 g
The foreign suggested retail price is the same as the 65mm f/2 lens: $699
The 20mm F2 DG DN maintains the same design language in appearance as the "I" series lenses previously released by Sigma, with clear paragraphs between the components, and the dark and rounded mirror body is engraved with lens information and aperture scale, which fully reflects the simple beauty.
The various parts of the lens are tightly connected without frame, the focus ring rotates smoothly and oily, the aperture ring is scaled by 1/3 stop, and there is a solid sense of passage when turning, so the design is convenient for bracketing exposure and other scenes that need to be strictly controlled for exposure.
A closer look at the lenses of the Sigma "I" series will show that although the appearance is roughly the same, the lens diameter of the maximum aperture F2 will generally be one circle larger than the lens diameter of the maximum aperture F2.8 and F3.5, reaching 70mm.
From left to right, the I Series 20mm F2, 35mm F2, 45mm F2.8
For Sigma's own fp, fp L, 70mm is the perfect diameter, can ensure that after installing the lens, the machine does not lean forward or tilt, and the casual placement is also quite harmonious, and the 370g mirror body is one of the few lightweight choices in the wide-angle lens in terms of weight and appearance volume.
Speaking of the 20mm F2 lens itself, the MF/AF focus toggle button is still retained on the lens, and the black and white design can be seen at a glance in the auto/manual focus state, which is very practical.
The lens structure is 11 groups of 13 elements, including 1 FLD fluorite grade low dispersion lens, 1 SLD special low dispersion lens and three aspherical lenses, it can be seen that Sigma attaches great importance to the dispersion and aberration of this lens, and the material is quite real. As can be seen from the change in the lens group structure from the nearest focus distance to the infinity focus distance, this is a lens with an internal focus structure.
The frontmost lens group of the lens is slightly protruding like most ultra-wide angle lenses, but it does not affect the normal use of the filter at all, and the front lens group coating is pale green, and the angle is slightly deflected to appear purple-red.
The rear lens coating is similar in color to the front mirror group, the color is transparent, and the 9-page circular aperture blade can be clearly seen.
The tail of the lens is still made of high-strength brass mount, fixed with 4 screws, and there is a ring of rubber at the edge of the bayonet, which can play a role in preventing dust and dripping.
Wide-angle lenses generally use petal-shaped hoods due to their wide field of view, and in the Sigma I series, in addition to the 20mm F2 and 24mm F2 wide-angle lenses, other lenses use circular hoods.
In addition, the lens packaging also comes with a plastic lens cover and a metal lens cover, the metal lens cover is magnetically adsorbed to the lens, after installing the filter, it is best to use a plastic lens cover.
Theoretical testing
Sigma 20mm F2 DG DN is currently suitable for E mount and L mount, we use the version of the L mount, in the process of theoretical testing, the whole process of Panasonic S5 equipped with Sigma 20mm F2 DG DN shooting, the lens for the project sample, the specific performance is subject to the listing version.
001 Resolution test
By adjusting the aperture from F2 to F22, shoot the resolution test board and capture 100% center and corner images to view details. It can be seen that under the maximum aperture F2, the central picture quality of the picture has been very solid, the corner quality is slightly less than the center, but the quality is also very good; in the process of F2.8 ~ F8 several gears of shrinking the aperture, the picture quality gradually improves, F11 when the corner quality begins to decline, further close the small aperture to F16 and F22, the center and corner quality are further lost.
MTF curve
Sigma very strictly gave this 20mm F2 geometric optical MTF and wave optical MTF, it can be seen that even if the diffraction of light is taken into account, the quality of the lens is still good, the 10mm line is close to the starting point, the virtual and solid lines fit tightly, under the maximum aperture, in addition to the sharpness of the lens edge, the imaging contrast, sharpness and bokeh effect of the lens are maintained at a high level, for an ultra-wide-angle large-aperture lens, such a performance has been very good.
002 Bokeh test
Under the maximum aperture F2, the edge of the picture presents a lemon-like spot, after shrinking a stop of aperture, the spot immediately returns to a full circle, and there is almost no common embarrassing bread-like spot in the middle, which can be said to give the user more choice, and F8 begins to appear more obvious stars. Combined with the relatively good close-up shooting ability of this lens, the bokeh of the background light spot can be made larger and rounder.
003 Dispersed purple fringing
As with many previous "I" series lenses, the dispersion control of this lens is also very good, at the maximum aperture F2, the edge of the highlight object can be said to be almost completely invisible to dispersion, and there is no annoying purple edge or other color edge, for the field of view is wider, will include a large amount of picture information ultra-wide angle lens, such dispersion purple edge suppression effect can be said to be very practical.
004 Vignetting test
The Sigma 20mm F2 DG DN has a good vignetting angle, only at the maximum aperture F2 will produce vignetting angles, slightly close a stop to F2.8, vignetting almost disappears, and the overall vignetting performance is good.
005 Distortion test
Ultra-wide angle lens below 24mm, barrel distortion is often more obvious, this time we can see the Sigma 20mm F2 DG DN shooting picture by shooting brick walls, although it is not completely horizontal and vertical, but the distortion is very slight, the picture or video shooting will not have an impact, step back ten thousand steps, even if you have zero tolerance for distortion, we can also open the camera's distortion correction function on the host, then the distortion control of the head is more first-class.
006 Respiratory effect test
From the breathing effect test, it can be seen that as a wide-angle lens, the breathing effect control of the head is not bad, although the near object will produce a certain float due to the perspective of the wide-angle lens, which has a certain impact on more serious video shooting and creation, but it is not a big problem for daily shooting vlog and still photography.
Live-action experience
Compared with conventional focal length lenses and telephoto lenses, the wide-angle focal length has a certain degree of difficulty in use, which is a great test of composition skills, and if it is not used well, it will cause problems such as more and more picture information and miscellaneous, and the main body is not prominent. Generally, the focal length of the mobile phone we use is about 28mm, although 20mm is only 8mm less than 28mm, but the gap in perspective is huge, often used to express the panoramic view of architecture or sculpture.
The 20mm F2 DG DN has an excellent recent focusing distance, and when representing the subject, it can be close to the subject, and the picture will be more impactful with the help of certain perspective deformation. When shooting at close range, the background is bokeh soft.
The simple lines and exquisite structure of the interior of the building are very suitable for displaying with 20mm focal lengths, so we also brought a lens into the nearby art museum, where the 20mm F2 DG DN film rate is far more than we use it to sweep the street, and we can shoot the film with a hand, perhaps because the art museum itself reflects beauty everywhere, without us looking for angles and compositions everywhere.
Combined with the Sigma fp L, this combination minimizes the aggressiveness of professional equipment during shooting, and the weight of less than 900g further enhances the comfort during shooting. 20mm lens is wider, with the right horse fp L ultra-high pixels, can leave a considerable space for post-cropping, in the fp L can also be directly set 21:9 ratio, in the early stage can preview the post-cropping screen, the use of experience is quite good.
Original
The machine is set to 21:9 JPG straight out
In addition to the 20mm ultra-wide angle characteristics, F2's large aperture is also one of the highlights that can not be ignored, in the night shooting, F2's large aperture allows us to control the ISO at a low level, which is very helpful for high-pixel models such as fp L and α7R IV.
There are still 33 megapixels after cropping
Of course, when it comes to night lighting, we have to mention the wisdom difference of the wide-angle lens, the wisdom difference control at the edge of the picture is an important indicator to measure the quality of the wide-angle lens, especially for starry sky photography, the lens with poor wisdom control will make the light source at the edge of the picture produce an ugly "shell-like" spot, which cannot be removed in the later stage. From the following photo, it can be seen that the light at the edge of the picture basically maintains a similar form to the central light, and there is no obvious "broom tail", indicating that this lens should be able to shoot the starry sky scene, but unfortunately, due to the inability to see the stars in the center of Chongqing, the recent weather is not good, and there is no way to try it on the ground.
The lens will produce a more obvious starlight at F11, and the 9 odd aperture page will present 18-pin astral glow, which is a little more. Combined with the theoretical test part, the aperture is controlled at about F11, and a good overall picture quality and star effect can be obtained.
For some vlog users, in order to hold a selfie or change the shooting angle at any time, a lightweight wide-angle head is essential, and in the process of light handheld, it is also necessary to ensure that the picture is stable and available, so it is inevitable to open the fuselage to stabilize. The field of view of the 20mm lens can be well adapted to the composition needs of the picture after cropping, the subject is placed in the middle, you can shoot yourself and the surrounding environment within an arm's length, it is foreseeable that this 20mm F2 DG DN will become a good vlog user choice after the listing.
SIGMA 20mm F2 DG DN +Lumix S5
Review
Overall, this 20mm F2 DG DN has excellent picture quality and high comprehensive quality. Officially, the "I" series 20mm F2 is currently the most optically performing lens in the Sigma Contemporary series, and through testing we can also confirm this statement, it is indeed standing on the best balance between image quality and volume.
Sigma has several options in 20mm, there are zoom lens 14-24mm F2.8 DG DN, fixed focus lens 20mm F1.4 DG HSM, etc., but these are all larger Volume weight Art series lenses, this "I" series 20mm F2 DG DN is undoubtedly to give E-port, L-port users a lighter, more cost-effective choice.
merit:
1. Small and portable
2, metal material, solid material
3. The nearest focus distance is very short, and the wide-angle close-up is very easy to use
4. It is very good as a vlog lens, and the wide field of view provides cutting and stabilization space
5. The cost performance is quite high compared with similar products
shortcoming:
1. The vignetting angle is more obvious when the aperture is fully open F2
▶ Picture samples
Sigma fp L + I series 20mm F2 DG DN | F9 ISO100 1/100s |
Sigma fp L + I series 20mm F2 DG DN | F2 ISO400 1/30s |
Lumix S5 + I series 20mm F2 DG DN | F2 ISO100 1/100s |
Lumix S5 + I series 20mm F2 DG DN | F2 ISO100 1/800s |
Lumix S5 + I series 20mm F2 DG DN | F3.2 ISO400 1/500s |