Quick lenses, just like the Sigma 20mm f/1.4 DG HSM ART lens, aren’t all the time low cost. And low cost lenses aren’t all the time good. The paradox is that astrophotography generally is a spendy recreation – it’s not simply the digital camera gear you want, it’s the star monitoring accoutrements as nicely, which suggests each penny counts in relation to lenses.
Key Specs:
Sort: 20mm prime lens for full-frame and APS-C sensor cameras.
Compatibility: Out there mounts: Canon EF, Nikon F-mount, Sony E-mount, Sigma SA-mount.
Focal vary: 20mm fastened focal size.
Aperture vary: f/2.8-f/16 fixed.
Thread measurement: No filter thread.
Weight: 1kg
Drawback is, an affordable lens goes to inform in relation to star images, wide-field or in any other case. Distortion, comatic aberration, purple fringing – should you penny-pinch on optics you would be setting your self up for long-term disappointment.
Into the fray launches the Sigma 20mm f/1.4 DG HSM ART lens (opens in new tab). At a little bit underneath $899 (£800) it’s not the most cost effective of a budget, however neither is it the Sigma 14mm f/1.8 DG HSM ART (opens in new tab). It’s an excellent focal size for astrophotography, and that tempting, large aperture means it completely drinks in gentle, providing you with loads of choices in relation to the way you arrange your exposures. However is it any good?
Sigma 20mm f/1.4 DG HSM ART lens assessment: Design
- 1kg weight
- Autofocus
- No filter thread
We’re massive followers of Sigma’s ART vary of lenses (see our 14mm f/1.8 and 12-24mm f/2.8 critiques to see us in full fanboy movement), and a part of that’s the construct high quality of the lenses. Right here, Sigma’s expertise constructing pro-grade lens is totally evidenced: high quality supplies and great-feeling development make it instantly apparent the place your cash has gone versus the cheaper finish of the astrophotography scale.
The glass is organized in 11 teams, with 15 components in complete. Some are FLD (‘F’ Low Dispersion) glass, and a few are SLD (‘Particular’ Low Dispersion) within the title of chromatic aberration management, whereas Sigma claims its Tremendous Multi-Layer Coating retains flare and ghosting in test.
That 20mm focal size is a handy one, and since it’s not on the super-wide finish of issues it means this lens has sensible purposes past astrophotography; due to its vibrant most aperture and autofocus (extra on which in a second) it’s nicely suited to industrial photographic jobs reminiscent of occasions, christenings, inside images and extra.
There’s no picture stabilization, which gained’t fear most astrophotographers, and contributes to the lens’ low weight. It really varies ever so barely relying on which model of the lens you purchase – the Sigma SA-mount model weighs 950g; the L-mount model 1.035kg. That low weight does come at a slight price, which is that the pro-grade climate sealing on a few of Sigma’s different ART-series lenses is lacking right here. On condition that astrophotography tends to be a fair-weather exercise most readers right here gained’t thoughts, nevertheless it’s value remembering should you’re shopping for this lens for extra basic adventuring.
The aperture is, by any requirements, a giant ‘un. At f/1.4 it offers you a big selection of choices in relation to exposures. 9 aperture blades make for comfortable-looking bokeh, though defocused areas of the body are usually a lesser concern for astro varieties. Nonetheless, it’s two stops sooner than an f/2.8 lens, so working backwards meaning should you’re capturing 30 seconds at ISO 3200 on an f/2.8 lens, you should use the 20mm f/1.4 and cut back the ISO to 800 with out altering the general publicity of the picture. We’re not saying the 20mm ART was designed with astrophotography particularly in thoughts, nevertheless it actually ticks numerous bins.
One space the place it ticks fewer bins – none, in truth – is for photographers who wish to use it with filters. This mainly applies to panorama snappers, though well-equipped astro varieties with gentle air pollution filters and so forth may also take curiosity. As with a few of its different ultra-wide, ultra-bright lenses, the design right here doesn’t permit for a conventional threaded filter ring, so if you wish to use a filter, you’ll want to purchase a third-party adapter. The 20mm f/1.4 is pretty fashionable with the cinematic group, so there are just a few of those about – it’s value checking there’s one thing that meets your wants, although.
A last consideration is focal size – 20mm is loads large, however wider lenses are on the market, and followers of the 500-rule will know these could make a giant distinction to shutter speeds, with knock-on results for ISO settings. At 20mm, for instance, the five hundred rule permits an publicity as much as 25 seconds with out trailing stars; at 14mm you get an additional 10 seconds. Thoughts you, we tried our assessment pattern on the MoveShootMove star tracker and acquired some wonderful outcomes.
Sigma 20mm f/1.4 DG HSM ART lens: Efficiency
- Effectively-controlled chromatic aberration
- Geometric pictures, even at wide-angles
- Sharp from nook to nook
Sooner or later Sigma will produce a stinker in its ART lens vary, at which level we’ll be capable to cease writing issues like, ‘we had been anticipating nice issues’ however at this time’s not the day, as a result of the 20mm f/1.4 is emphatically not a stinker.
Extremely-large aperture lenses often throw up issues if you use them at their widest aperture, and whereas the 20mm f/1.4 isn’t at its very best when it’s positively consuming in gentle, it’s nonetheless very, excellent. It’s extraordinarily sharp on the centre of the picture – comparable, we’d say, to some far dearer lenses together with a few of Canon’s superlative RF-mount L-series glass – and though there’s a little bit little bit of softness creeping in across the periphery of the picture, it’s important to crop pretty aggressively to see it. To which a pragmatist would say, merely body up your topic in the midst of the body and also you gained’t have to fret about it.
Coma? There’s a bit, with stars starting to look a little bit elongated comparatively near the centre of the body. Fortunately, with such a variety of aperture values obtainable, should you don’t like how the lens handles pinpricks of sunshine you may all the time cease down with out ruining your body.
You shouldn’t overlook that there are a selection of cheap high quality, autofocus-free lenses on the market, such because the Samyang 20mm f/1.8 ED AS IF UMC (opens in new tab), and whereas there are just a few variations by way of high quality – areas by which the Sigma is superior – the query of autofocus is value mentioning, as most wide-angle lenses will discover themselves deployed to non-astrophotography locations in some unspecified time in the future. The lens makes use of Sigma’s Hyper Sonic, which runs swiftly and silently. There are snappier-feeling lenses on the market, however in use it’s not too irritating and positively falls into the ‘good to have’ class.
Must you purchase the Sigma 20mm f/1.4 DG HSM ART lens?
The positives pile up fairly rapidly when you begin to checklist the professionals and cons of this wonderful little piece of astrophotography equipment. It may possibly weigh underneath 1kg, which is nice for these instances when the right viewpoint is a way over the horizon and also you’re already lugging a tripod, a star tracker, a Thermos filled with espresso and all of the accoutrements of an evening underneath the celebrities. That such a lightweight lens is ready to produce such high-quality pictures is a testomony to the design impresarios at Sigma.
It’s not the one spectacular factor about this lens. The construct high quality is convincing, and whereas it could be weather-sealed, there’s nothing about its development that makes us suppose it must be dealt with with child gloves.
Greater than something, it shoots nice pictures. In comparison with the manual-focus-only crowd on the decrease finish of the market that is tremendous sharp and tremendous vibrant, and meaning simpler astrophotography and decrease ISOs, which inevitably means technically superior pictures. It is a much-loved astrophotography lens for a motive.
If this product isn’t for you
Can’t deliver your self to spend the cash? We’ve acquired you. Contemplate lenses such because the Rokinon 20mm f/1.8 AS ED UMC (opens in new tab), which doesn’t have autofocus, however astrophotographers gained’t thoughts. Alternatively, there are lenses on the market that dispose of the restrictions of prime focal lengths – contemplate Sigma’s personal Sigma 14-24mm F2.8 DG HSM Artwork, (opens in new tab) or Nikon’s Nikkor 14-24mm F/2.8 G (opens in new tab). Canon followers may go for the RF 15-35mm f/2.8L IS USM (opens in new tab) – a considerably extra sensible focal size for all-purpose images, albeit at the price of a little bit of aperture and fairly some huge cash – Canon’s present wide-angle quick lens will set you again a bit over $2300 (£2,000).
