Review of the fast wide-angle lens 7Artisans 28/1.4 DJ-OPTICAL (Leica M)

Material on the 7Artisans 28/1.4 DJ-OPTICAL lens especially for Radozhiva prepared Rodion Eshmakov.

The modern manual wide-angle lens DJ-OPTICAL 7Artisans 28/1.4 (hereinafter simply 7artisans 28/1.4) was introduced in 2018 and is only available with the Leica M mount, which, however, allows you to install the lens on most mirrorless systems. There are two versions of the lens: a regular version - optimized for Leica cameras (presented in this article), and a specially optimized FE+ version for Sony cameras and other mirrorless cameras with a thick matrix filter compared to the Leica M.

Reviews of other optics 7artisans - here.

Specifications:

Optical design – 11 lenses in 9 groups, 1 lens with 2 aspherical surfaces (double sided aspherical), 2 lenses made of low dispersion glass (ED), 3 lenses made of highly refractive glass (high refractive, n>1.8);

Focal length - 28 mm;
Relative aperture - 1: 1.4;
Field of view - 75 °;
Frame format - 36 × 24 mm (full-frame lens);
Aperture - 13 blades;
Aperture limits – 1:1.4-1:16, 8 discrete positions of the aperture control ring;
The focusing method is manual, autofocus is available when using a special adapter such as Techart Leica M-Sony E https://radojuva.com/2017/06/message-from-io-techart/.
The minimum focusing distance is 0.7 m;
Thread for filters – 52 mm;
Camera mount – Leica M mount;
Case dimensions – 72×56 mm;
Weight - 488 g;
Price – ~$400.

Design and execution

7artisans 28/1.4 is made in the best traditions of old manual optics - entirely made of metal and glass. Both aluminum and brass were used as materials - because of this, the lens turned out to be quite heavy - almost 500 g. The design of the lens copies Leica optics, although whether the finish reaches the level of a famous manufacturer is a question: on my by no means new lens, the applied ones have noticeably worn out designations (poor engraving?) and the focus ring screws are for some reason a contrasting gray-white color. And on this lens there is a stupid inscription “DJ-OPTICAL”, which you can bashfully cover up by putting it on the lens safety filter. By the way, on the Internet there is interview with one of the “optical DJs” - the developer of the 7artisans line of lenses and the founder of the company.

As befits a typical manual, the 7artisans 28/1.4 has a standard set of scales - distance values ​​on the focusing ring, a depth of field scale on the eyepiece (it’s better not to rely on it when shooting with digital cameras), aperture number marks on the aperture control ring. There is also a convex red dot for easy installation of the lens into the camera mount or adapter.

The 7artisans 28/1.4 lens is designed for rangefinder cameras with a Leica M mount and supports pairing with a rangefinder.

As a result, the lens has a very large minimum focusing distance - as much as 0.7 m - it is problematic to focus at shorter distances using an optical rangefinder. This MDF is very large for a 28 mm lens: for example, an old lens Pentacon 29 / 2.8 for SLR cameras it could focus at a distance of only 0.25 m, which made it possible to shoot various close-up scenes with it.

With an MDF of 0.7 m, even part of the “portrait” range becomes inaccessible (and portraits are being taken with wide-angle lenses more and more often, largely due to the habit of taking pictures from smartphones). When used on mirrorless cameras, fortunately, this problem can be solved by using adapters equipped with an additional helicoid. It was often more convenient to use such an adapter for focusing than using a lens focusing ring.

The 7artisans 28/1.4 aperture is controlled using a single ring, and 8 discrete positions from F/1.4 to F/16 are available for installation. It is important to note that the ring markings are poorly done and in fact most of the values ​​on the ring correspond to an aperture that is 1/3-2/3 stops larger. Many Chinese lenses have this defect. Most likely, this was done so that when compared with other optics, the Chinese lens would always be “lighter” in shutter speed.

The iris diaphragm of the lens consists of 13 blades of a “regular” shape, which form an almost perfectly round hole at any aperture value. The petals have a dark matte finish. This aperture is not very suitable for creating the effect of stars from point light sources in a photo, since it forms 26 hard-to-see rays. For stars, apertures similar to those installed in lenses are better suited Voigtlander.

7artisans 28/1.4 lenses are coated with green and purple highlights. The lens flare is quite bright, which suggests that the Chinese did not bother much with the coating. It feels like even on an even older lens 7artisans 50/1.1 Leica M better coverage has been chosen.

7artisans 28/1.4 is positioned by the creator himself as a street photography lens by the founder of 7artisans, although in reality it is quite large and heavy for this purpose. Although if you compare it with fixes from SLR cameras like Nikkor 24 / 1.4 G, then, of course, the lens seems compact. In general, the 7artisans 28/1.4 has no serious design flaws, except for the traditionally large MDF and the traditionally (for Chinese manufacturers) haphazardly marked aperture scale.

Optical properties

7artisans 28/1.4 has mediocre optical quality at an open aperture: even in the central area the image has a pronounced soft effect due to the high level of spherical aberrations. At the edge of the frame, sharpness drops significantly due to the influence of field aberrations. It is worth noting that the drop in field resolution largely depends on the camera used with the lens. Thus, since the regular version (not FE+) 7artisans 28/1.4 is optimized for Leica M rangefinder cameras, the best image quality can be achieved when using the lens with cameras with a thin matrix filter. Learn more about the effect of a matrix filter on image quality - here.

The sharpness of the lens increases significantly in the central area of ​​the frame when aperture is f/1.4 to F/2.8 and then remains virtually unchanged. On camera Sony A7s An acceptable level of image quality across the field is achieved with F/5.6, although cameras with a higher resolution matrix may require apertures up to F/8-F/11 - fortunately, this really helps thanks to fairly well-corrected field curvature, astigmatism and lateral chromatic aberrations. In general, the correction of optical distortions was done very well, in some ways even better than in the “darker” Voigtlander Ultron 28/2 (test comparison of 7artisans 28/1.4 and Ultron 28/2 - here).

Due to the presence of aberrations at the open aperture, the 7artisans 28/1.4 has quite interesting, not at all “sterile” bokeh. The “oily” blur of the background is somewhat reminiscent of the pattern of old class lenses 35/2 and definitely more “correct” than the defiant design of old 28/1.8 class lenses.

But where the lens is bad is in its resistance to backlight and color rendering: the lens has a lot of glare and veils (green) in backlight, even diffused. Moreover, under normal conditions the contrast is at an acceptable level.

As noted above, the lens flare of the 7artisans 28/1.4 is quite obvious - like old lenses with multi-layer coating from the 80s. Taking into account the fact that there are 9 groups of lenses in the lens, we have 18 glass-air surfaces, which, of course, requires the use of a high-quality anti-reflective coating and its correct selection to perform three tasks: 1) achieving an acceptable level of light transmission, 2) eliminating excessive light scattering, 3 ) neutralization of the transmission spectrum (color rendering).

The transmission spectrum of the 7artisans 28/1.4 is very uneven, represented by a curve with two observable transmission maxima at ~440 nm and at ~650 nm - apparently, the lens uses a simple two-three-layer coating (although I do not observe any signs of the presence of a third layer in the spectrum). Camera matrices are sensitive to the range of 400-700 nm, with a predominant contribution from the region of ~420-670 nm. Thus, the transmission spectrum of 7artisans 28/1.4 greatly “cuts off” part of the working blue and red ranges, and also reduces the contribution of the blue-green part of the spectrum relative to the orange-red part as a whole, which affects the transmission defects of the corresponding colors. In other words, we have “dirty” blue, “dirty” red and a shift in both tone and color temperature. Add to this the green veil from 18 glass-air boundaries - and it becomes quite interesting.

Comments regarding color rendering and image contrast of the 7artisans 28/1.4 are not purely theoretical considerations. In practice, I had the opportunity to directly compare this lens with lenses Voigtlander Ultron 28/2 и 21/1.8, and the difference turned out to be colossal: photographs from Voigtlander lenses with their perfectly selected lens coatings rarely require interventions such as color correction and adding contrast, even when shooting in backlight, while photos from 7artisans 28/1.4 usually look much worse in this aspect and almost always require improvement. Thus, with better sharpness and twice the aperture speed compared to the Ultron 28/2, the 7artisans 28/1.4 is noticeably inferior in contrast and color rendition to modern Voigtlander Ultron lenses.

Below are examples of photographs taken with a full frame camera. Sony A7s.

Conclusions

7artisans 28/1.4 is a modern wide-angle lens with an attractively high aperture, which is really capable of providing a good level of sharpness with modern mirrorless cameras (even the regular version, not FE+) and, moreover, we have a nice image. However, there were some compromises - the lens turned out to be problematic in terms of color rendering and, especially, image contrast, which is why when choosing it is also worth considering optics with less aperture from more responsible manufacturers like Cosina.

You will find more reviews from readers of Radozhiva here и here.