Handling and Features
Performance
Verdict
Specification

The stream of interesting and sometimes unusual manual focus optics continues with the arrival of the Samyang 20mm f/1.8 ED AS UMC lens. The lens is available in a wide variety of mounts, so let's see how it performs with the Canon EOS 6D full frame DSLR used for this review.

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Samyang 20mm f/1.8 ED AS UMC Handling and Features

This is a full frame lens and also manual focus only. Having such a wide angle, the resulting depth of field makes manual focusing less easy, but provided wider apertures are used it is not too much of a problem. It does make adjusting the camera diopter setting on the viewfinder even more important than usual. The easiest technique is to focus at open aperture and then stop down for making the exposure. It is a matter of practice to be able to set an aperture by feel or counting click stops, without removing the camera from the eye.

Mount options are listed as Canon EOS, Nikon, Pentax K, Sony A, Canon M, Fujifilm X, Samsung NX, Sony E, Four Thirds and MFT. Interestingly, the focusing direction is geared to the camera type. So, for example, Canon fit lenses focus in the reverse direction to Nikon or Pentax. The Canon fit sample reviewed did not extend this logic to the aperture ring, which turned in the Nikon/Pentax direction. The advantage is that lenses of marque origin and the Samyang lens can be used side by side with no confusion as to which way the focusing turns.

The only question mark as to the selection of mounts is that, whilst 20mm is a great lens for full frame cameras, as formats become smaller the “35mm equivalent” results in an increasingly normal looking result. So, for example, on APS-C format we have a 35mm equivalent of around 35mm and on MFT 40mm. In both these cases, we have a wide standard lens.

As always, the finish of the lens is excellent, starting with the precisely fitting bayonet lens hood. This surrounds a 77mm filter thread. Behind this sits the wide and comfortable focusing ring, clearly marked in feet and metres. Sadly, there is no depth of field scale. Finally, we find the aperture ring, which operates smoothly, with light but secure click stops. The detents are at half stop intervals, but with three steps between open aperture and f/2.8 and just one step between f/16 and f/22. The mount is well engineered and is totally devoid of electronics.

Construction comprises 13 elements in 12 groups, using 3 ED (extra-low dispersion) and 2 aspherical elements. Focusing is down to a reasonably close 0.2m (0.66 feet). There is a small extension of the optical components when focusing close, but it consists of very little movement and is well contained within the large baffle surrounding the front element. The diaphragm comprises 7 blades, which does not offer a completely round shape. At 487g (varies with mount chosen) we have a chunky but well-balanced lens that matches the supplied Canon 6D very well.

In terms of general handling, there were no operational issues and the lens proved to be a pleasure to use. The 20mm focal length does give a satisfyingly wide view that can be used creatively as well as for the more usual applications such as interiors and architecture.

Samyang 20mm f/1.8 ED AS UMC Performance

The central performance of the Samyang 20mm f/1.8 ED AS UMC lens in terms of sharpness is exceptional. Open aperture is excellent and apertures from f/2.8 through to f/16 offer outstanding sharpness. Diffraction eventually hits at f/22 but here the result is still very good.

The full frame edges are not quite in the same league, but do give a very good level of sharpness from f/1.8 to f/16. Only at f/22 do we see this dip to a softer but still good performance. It should also be borne in mind that lenses such as this are not intended for photographing test charts at close distances. Despite this caveat, the lens acquits itself very well indeed.

The optimum aperture for the whole field is f/8, but for an ultra-wide lens this is overall a really excellent result. High-quality results can be expected from full frame cameras, but obviously smaller formats will have the advantage of a more even balance between centre and edge.

MTF
 

How to read our charts

The blue column represents readings from the centre of the picture frame at the various apertures and the green is from the edges.

The scale on the left side is an indication of actual image resolution as LW/PH and is described in detail above. The taller the column, the better the lens performance.

For this review, the lens was tested on a Canon EOS 6D using Imatest.

There is virtually no CA (Chromatic Aberration) at the centre, but, unsurprisingly, the edges do show some fringing. This can easily be corrected in software.

CA
 

How to read our charts

Chromatic aberration is the lens' inability to focus on the sensor or film all colours of visible light at the same point. Severe chromatic aberration gives a noticeable fringing or a halo effect around sharp edges within the picture. It can be cured in software.

Apochromatic lenses have special lens elements (aspheric, extra-low dispersion etc) to minimise the problem, hence they usually cost more.

For this review, the lens was tested on a Canon EOS 6D using Imatest.

Ultra-wide lenses are generally quite susceptible to flare but in this case, the lens is remarkably flare free. It is possible to induce some artefacts, but in most situations flare is not a problem.

We would normally anticipate some barrel distortion in a 20mm lens design, and this is no exception. However, the -2.26% barrel distortion measured is really quite moderate, and if needed, perhaps for critical architectural shots, then it can be corrected in software.

With only 7 blades to the diaphragm the aperture is not particularly circular, so in this respect, the out of focus highlights take on the traditional hard-edged shape. The bokeh is good, but not the exceptional smoothness that some lenses have. The effect is slightly “busy” but certainly not so much so as to be unpleasant.

Samyang 20mm f/1.8 ED AS UMC Sample Photos

Value For Money

The Samyang 20mm f/1.8 ED AS UMC lens is priced at £430. There are numerous alternatives, although few at f/1.8. Samyang offers another manual focus lens, the 20mm T1.9 VD SLR ED AS IF UMC, at £479.

Sigma has a brighter AF offering, the 20mm f/1.4 DG HSM Art at £629. Nikon has the 20mm f/1.8 AF-S Nikkor G ED at £649. Canon users have just one slower lens, the Canon EF 20mm f/2.8 USM, priced at £409.

Given that it is a manual focus lens, the new Samyang might be seen as fair value. The Nikon AF alternative, for example, costs a good £200 more.

For more options have a look at the Top 10 Best Samyang lenses or have a look at the Top 15 Wide-angle Lenses.

Samyang 20mm f/1.8 ED AS UMC Verdict

20mm lenses are very attractive for the wide angle photographer, wide enough to be interesting, but not so wide as to be very difficult to handle. We have here a lens that is well made, has a very high standard of performance, and a reasonable price tag. Without doubt, the Samyang 20mm f/1.8 ED AS UMS adds up to being a very good deal.

The Samyang 20mm f/1.8 is a well made high performance lens that is a pleasure to use.

Samyang 20mm f/1.8 ED AS UMC Specifications

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