Review and test of the modern ultra wide-angle lens Voigtländer Ultron 21mm F1.8 Aspherical for rangefinder cameras (Leica M)

Material on the Voigtländer Ultron 21mm F1.8 Aspherical lens especially for Radozhiva prepared Rodion Eshmakov.

Voigtländer Ultron 21mm F1.8 Aspherical (hereinafter referred to as Ultron 21/1.8) is a fast ultra-wide-angle manual lens developed in 2012 for use with mount rangefinder cameras Leica M, but also compatible via adapters with conventional mirrorless cameras. Until the introduction of the Voigtländer Nokton 21/1.4 in 2019, this lens was Voigtländer's fastest ultra-wide-angle lens and is certainly a high-end lens even now.
It is worth noting that although Voigtländer is formally German (of Austrian origin), all modern lenses (since 1999) are designed and manufactured by a Japanese company Cosina (also producing optics for Zeiss).

Reviews of other Voigtländer lenses:

• Voigtländer Braunschweig Heliar 1:4,5 F=13,5cm (1928)
• Voigtlander APO-Lanthar 90mm F3.5 SL N / AI-S
• Voigtlander Nokton 58mm F1.4 SL N / AI-S

Specifications (from the manufacturer's page):

Optical design - 13 lenses in 11 groups, 1 aspherical element;

Focal length - 21 mm;
Field of view - 91 °;
Estimated frame format - 36 × 24 mm;
Relative aperture - 1: 1.8;
Aperture - iris, 10 "straight" petals;
Aperture limits - 1: 1.8–1: 22, stepwise adjustment (with half stops and F / 2);
Focusing - only manual, autofocus on the UPC through a special adapter https://radojuva.com/2017/06/message-from-io-techart/;
Minimum focusing distance (MDF) - 0.5 m;
Thread diameter for filters - 58 mm;
Camera mount - Leica M mount (with the ability to interface with a rangefinder);
Dimensions - 69 × 78.4 mm;
Weight - 412 g;
Miscellaneous - built-in non-removable sun hood;
The cost is ~1200 USD.

Design and execution of the lens

The lens given to me for this article was brand new in the box. The delivery set is very modest: a lens with caps and a small instruction sheet. I even thought - maybe they got something from there to me? But there is no room for anything else in the box - and this is very funny, because even $ 60 TTArtisan 50 / 2 the set looks richer.

However, the manufacturer does not need to create the illusion of premium: the lens gives the impression of a very high-quality thing in itself. The body of the Ultron 21/1.8 is made entirely of metal and covered with a pleasant to the touch black matte anodization. The coating looks and feels much better than, for example, Zenitar 50/0.95 E. The lens has scales for aperture values, distances (red - in feet, white - in meters), depth of field. All marks on the lens are engraved and filled with paint, that is, they are made “for centuries”.

A distinctive feature of the lens is the presence of a built-in and non-removable hood. On the one hand, this solution helps to prevent damage to the front lens of the lens during use, since the hood petals will not scratch the glass on any surface and will most likely take a hit in a collision. And the hood will never hang out and fly off if they are non-removable. The reverse side of the medal is an increase in dimensions, “sharp” body contours (impractical when worn with other things).

Ultron 21/1.8 has a wide and comfortable focus ring. The ring travel is small - approximately 60 °, but the minimum focusing distance is as much as 0.5 m - so focusing at medium distances is quite comfortable. But you can forget about shooting small things close-up without the use of special devices. Like other lenses with Leica M mount I have used this one on Sony A7s through the LM-NEX macrohelicoid adapter, which made it possible to take close-up shots from a distance of a few centimeters from the front lens.

The bayonet of the Ultron 21/1.8 is not black, like the whole body, but chrome-plated. The name of the manufacturer (Cosina) is inconspicuously engraved on the bayonet. Also, from the side of attachment to the camera, you can see the rangefinder pusher, which is absent, for example, in 7artisans 35/5.6wen.

The lens iris consists of 10 dark matte blades, which provide an almost round aperture at f / 22, but at values ​​​​intermediate between F / 1.8 and F / 22, the lens pupil has the shape of a regular decagon with unrounded corners.

Most likely, the aperture blades of the lens have a complex shape, similar to the aperture Helios-103. There are two goals pursued in this case. The first of them is to provide a more “stretched” diaphragm scale in the region of small apertures (linearization of the diaphragm ring travel). Sometimes diaphragms with L-shaped petals that form the pupil are also used for this. in the form of a star. The second goal is to make it possible to obtain a pronounced effect of a ten-pointed star from bright point light sources in the frame when shooting at covered apertures.

The diaphragm is controlled by a separate ring with a stepped stroke. There are clicks for F / 1.8, F / 2 and beyond, up to F / 22 - after 1/2 steps. The course of the ring is optimal in terms of force, the marking does not raise questions, as in the case of Chinese lenses.

The mass of the lens is almost half a kilogram - together with its impressive dimensions, this automatically removes the lens from the list of "light and compact", "every day" or "street photography". For the latter, it would be much nicer to use something more dark and small .

Appearance, layout, ergonomics Voigtländer Ultron 21/1.8 make a very good impression. The lens has a well-thought-out design and very high-quality workmanship. Probably, it should be so at a cost of> $ 1000.

Optical properties. Comparison with New Russar+ 20/5.6

The modern, sophisticated and, obviously, high-quality Voigtländer Ultron 21 / 1.8 was quite interesting to compare with the progenitor of all modern ultra-wide-angle lenses - Russar MP-2 20 / 5.6, which in an updated version New Russar+ 20/5.6 I was given at the same time as Ultron. Tests conducted in the far field using a mirrorless camera Sony A7s.

Below are shots taken on the Ultron 21/1.8 at apertures from F/1.8, F/2 to F/22.

Next - shots on Russar + 20 / 5.6 at F / 5.6, F / 8, F / 11.

It can be immediately noted that over 80 years of progress, Japanese engineers managed to make the level of vignetting even lower than that of the Rusinov lens, which for a long time had the best distribution of illumination over the field among non-retrofocus wide-angle lenses.

When considering 100% crops of the central area of ​​the frame, you can see that Ultron 21 / 1.8 with an open aperture is not worse at all than Russar + at f / 8. And at F / 5.6, the museum exhibit loses a lot in sharpness due to pronounced spherical aberration.

Similarly, it turns out that the optical quality at the edge of the frame Ultron 21 / 1.8 at F / 2.8 is equivalent to Russar + 20 / 5.6 at F / 8. At an open aperture, the Ultron still suffers from some field distortion.

Finally, the corners of the Ultron 21 / 1.8 at F / 2.8 look much better than the Russar at F / 11. However, this may also be due to the influence of the matrix filter on image quality when using Russar+ 20/5.6 on Sony A7s, what is dedicated to a significant part of the review of this lens. Interestingly, with the Ultron 21/1.8, there were far fewer problems due to the filter than I expected.

Thus, Ultron 21/1.8 provides high image quality within the ~APS-C frame already at F/1.8, and a small aperture up to F/2.8-F/4 makes the lens completely sharp in the field. Of the aberrations, only small residual distortions of higher orders are observed, forming a “modern” lens pattern, as well as noticeable transverse chromatism at the edge of the frame. Probably, on cameras with high-resolution matrices (>36 megapixels at 36×24 mm format), lateral chromatism will be the only distortion that limits the quality at small apertures. Ultron 21 / 1.8 has a small, almost imperceptible distortion.

The quality of the antireflection coating of the objective lenses deserves high praise: despite the eleven-component construction (22 glass-to-air surfaces!) Ultron 21/1.8 is distinguished by high image contrast and excellent color reproduction. Measurement of the transmission spectrum showed that the lens really has a high-quality coating that provides a smooth transmission profile in the range from 430 nm to 700 nm, which practically covers the entire spectral sensitivity range of a conventional RGB matrix (~410-650 nm). To obtain a curve of this shape, 4-5 coating layers are required, which makes the production of lens optics more expensive than lenses of the same complexity, but with two or three layers of coating, about twice. It is important to note that the spectrum profile is devoid of obvious peaks or dips, which has a positive effect on the color reproduction of the lens. There is only characteristic absorption in the violet region of the spectrum, due to both the properties of the coating (weak violet reflection) and the optical density of the objective lens materials.

The pupil size of the Ultron 21/1.8 is enough to form a pronounced background blur in a number of situations. Due to good aberration correction, the Ultron 21/1.8 has soft, even bokeh with clear discs that turn into “lemons” at the edge of the frame. With this lens it is quite interesting to shoot portraits, playing with perspective for the sake of "presence" effect and geometric accents. The lens is definitely suitable for landscape photography, architecture, indoor photography, and not only interior photography, but also portrait photography.

The following are sample shots taken with a full-frame mirrorless camera. Sony A7s.

Conclusions

The Voigtländer Ultron 21/1.8 is an excellent lens with attractive parameters, thoughtful performance and high optical quality. An excellent option for perfectionists among connoisseurs of fast optics. Far from ideal for compact lens lovers.

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